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_ROOT;
 108         tree->buffer = RB_ROOT;
 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 bits_to_clear = bits & ~EXTENT_DO_ACCOUNTING;
 464         int ret = state->state & bits_to_clear;
 465
 466         if ((bits & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 467                 u64 range = state->end - state->start + 1;
 468                 WARN_ON(range > tree->dirty_bytes);
 469                 tree->dirty_bytes -= range;
 470         }
 471         clear_state_cb(tree, state, bits);
 472         state->state &= ~bits_to_clear;
 473         if (wake)
 474                 wake_up(&state->wq);
 475         if (delete || state->state == 0) {
 476                 if (state->tree) {
 477                         clear_state_cb(tree, state, state->state);
 478                         rb_erase(&state->rb_node, &tree->state);
 479                         state->tree = NULL;
 480                         free_extent_state(state);
 481                 } else {
 482                         WARN_ON(1);
 483                 }
 484         } else {
 485                 merge_state(tree, state);
 486         }
 487         return ret;
 488 }
 489
 490 /*
 491  * clear some bits on a range in the tree.  This may require splitting
 492  * or inserting elements in the tree, so the gfp mask is used to
 493  * indicate which allocations or sleeping are allowed.
 494  *
 495  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 496  * the given range from the tree regardless of state (ie for truncate).
 497  *
 498  * the range [start, end] is inclusive.
 499  *
 500  * This takes the tree lock, and returns < 0 on error, > 0 if any of the
 501  * bits were already set, or zero if none of the bits were already set.
 502  */
 503 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 504                      int bits, int wake, int delete,
 505                      struct extent_state **cached_state,
 506                      gfp_t mask)
 507 {
 508         struct extent_state *state;
 509         struct extent_state *cached;
 510         struct extent_state *prealloc = NULL;
 511         struct rb_node *next_node;
 512         struct rb_node *node;
 513         u64 last_end;
 514         int err;
 515         int set = 0;
 516         int clear = 0;
 517
 518         if (bits & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 519                 clear = 1;
 520 again:
 521         if (!prealloc && (mask & __GFP_WAIT)) {
 522                 prealloc = alloc_extent_state(mask);
 523                 if (!prealloc)
 524                         return -ENOMEM;
 525         }
 526
 527         spin_lock(&tree->lock);
 528         if (cached_state) {
 529                 cached = *cached_state;
 530
 531                 if (clear) {
 532                         *cached_state = NULL;
 533                         cached_state = NULL;
 534                 }
 535
 536                 if (cached && cached->tree && cached->start == start) {
 537                         if (clear)
 538                                 atomic_dec(&cached->refs);
 539                         state = cached;
 540                         goto hit_next;
 541                 }
 542                 if (clear)
 543                         free_extent_state(cached);
 544         }
 545         /*
 546          * this search will find the extents that end after
 547          * our range starts
 548          */
 549         node = tree_search(tree, start);
 550         if (!node)
 551                 goto out;
 552         state = rb_entry(node, struct extent_state, rb_node);
 553 hit_next:
 554         if (state->start > end)
 555                 goto out;
 556         WARN_ON(state->end < start);
 557         last_end = state->end;
 558
 559         /*
 560          *     | ---- desired range ---- |
 561          *  | state | or
 562          *  | ------------- state -------------- |
 563          *
 564          * We need to split the extent we found, and may flip
 565          * bits on second half.
 566          *
 567          * If the extent we found extends past our range, we
 568          * just split and search again.  It'll get split again
 569          * the next time though.
 570          *
 571          * If the extent we found is inside our range, we clear
 572          * the desired bit on it.
 573          */
 574
 575         if (state->start < start) {
 576                 if (!prealloc)
 577                         prealloc = alloc_extent_state(GFP_ATOMIC);
 578                 err = split_state(tree, state, prealloc, start);
 579                 BUG_ON(err == -EEXIST);
 580                 prealloc = NULL;
 581                 if (err)
 582                         goto out;
 583                 if (state->end <= end) {
 584                         set |= clear_state_bit(tree, state, bits, wake,
 585                                                delete);
 586                         if (last_end == (u64)-1)
 587                                 goto out;
 588                         start = last_end + 1;
 589                 }
 590                 goto search_again;
 591         }
 592         /*
 593          * | ---- desired range ---- |
 594          *                        | state |
 595          * We need to split the extent, and clear the bit
 596          * on the first half
 597          */
 598         if (state->start <= end && state->end > end) {
 599                 if (!prealloc)
 600                         prealloc = alloc_extent_state(GFP_ATOMIC);
 601                 err = split_state(tree, state, prealloc, end + 1);
 602                 BUG_ON(err == -EEXIST);
 603                 if (wake)
 604                         wake_up(&state->wq);
 605
 606                 set |= clear_state_bit(tree, prealloc, bits, wake, delete);
 607
 608                 prealloc = NULL;
 609                 goto out;
 610         }
 611
 612         if (state->end < end && prealloc && !need_resched())
 613                 next_node = rb_next(&state->rb_node);
 614         else
 615                 next_node = NULL;
 616
 617         set |= clear_state_bit(tree, state, bits, wake, delete);
 618         if (last_end == (u64)-1)
 619                 goto out;
 620         start = last_end + 1;
 621         if (start <= end && next_node) {
 622                 state = rb_entry(next_node, struct extent_state,
 623                                  rb_node);
 624                 if (state->start == start)
 625                         goto hit_next;
 626         }
 627         goto search_again;
 628
 629 out:
 630         spin_unlock(&tree->lock);
 631         if (prealloc)
 632                 free_extent_state(prealloc);
 633
 634         return set;
 635
 636 search_again:
 637         if (start > end)
 638                 goto out;
 639         spin_unlock(&tree->lock);
 640         if (mask & __GFP_WAIT)
 641                 cond_resched();
 642         goto again;
 643 }
 644
 645 static int wait_on_state(struct extent_io_tree *tree,
 646                          struct extent_state *state)
 647                 __releases(tree->lock)
 648                 __acquires(tree->lock)
 649 {
 650         DEFINE_WAIT(wait);
 651         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 652         spin_unlock(&tree->lock);
 653         schedule();
 654         spin_lock(&tree->lock);
 655         finish_wait(&state->wq, &wait);
 656         return 0;
 657 }
 658
 659 /*
 660  * waits for one or more bits to clear on a range in the state tree.
 661  * The range [start, end] is inclusive.
 662  * The tree lock is taken by this function
 663  */
 664 int wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, int bits)
 665 {
 666         struct extent_state *state;
 667         struct rb_node *node;
 668
 669         spin_lock(&tree->lock);
 670 again:
 671         while (1) {
 672                 /*
 673                  * this search will find all the extents that end after
 674                  * our range starts
 675                  */
 676                 node = tree_search(tree, start);
 677                 if (!node)
 678                         break;
 679
 680                 state = rb_entry(node, struct extent_state, rb_node);
 681
 682                 if (state->start > end)
 683                         goto out;
 684
 685                 if (state->state & bits) {
 686                         start = state->start;
 687                         atomic_inc(&state->refs);
 688                         wait_on_state(tree, state);
 689                         free_extent_state(state);
 690                         goto again;
 691                 }
 692                 start = state->end + 1;
 693
 694                 if (start > end)
 695                         break;
 696
 697                 if (need_resched()) {
 698                         spin_unlock(&tree->lock);
 699                         cond_resched();
 700                         spin_lock(&tree->lock);
 701                 }
 702         }
 703 out:
 704         spin_unlock(&tree->lock);
 705         return 0;
 706 }
 707
 708 static int set_state_bits(struct extent_io_tree *tree,
 709                            struct extent_state *state,
 710                            int bits)
 711 {
 712         int ret;
 713
 714         ret = set_state_cb(tree, state, bits);
 715         if (ret)
 716                 return ret;
 717
 718         if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 719                 u64 range = state->end - state->start + 1;
 720                 tree->dirty_bytes += range;
 721         }
 722         state->state |= bits;
 723
 724         return 0;
 725 }
 726
 727 static void cache_state(struct extent_state *state,
 728                         struct extent_state **cached_ptr)
 729 {
 730         if (cached_ptr && !(*cached_ptr)) {
 731                 if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) {
 732                         *cached_ptr = state;
 733                         atomic_inc(&state->refs);
 734                 }
 735         }
 736 }
 737
 738 /*
 739  * set some bits on a range in the tree.  This may require allocations or
 740  * sleeping, so the gfp mask is used to indicate what is allowed.
 741  *
 742  * If any of the exclusive bits are set, this will fail with -EEXIST if some
 743  * part of the range already has the desired bits set.  The start of the
 744  * existing range is returned in failed_start in this case.
 745  *
 746  * [start, end] is inclusive This takes the tree lock.
 747  */
 748
 749 static int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 750                           int bits, int exclusive_bits, u64 *failed_start,
 751                           struct extent_state **cached_state,
 752                           gfp_t mask)
 753 {
 754         struct extent_state *state;
 755         struct extent_state *prealloc = NULL;
 756         struct rb_node *node;
 757         int err = 0;
 758         u64 last_start;
 759         u64 last_end;
 760
 761 again:
 762         if (!prealloc && (mask & __GFP_WAIT)) {
 763                 prealloc = alloc_extent_state(mask);
 764                 if (!prealloc)
 765                         return -ENOMEM;
 766         }
 767
 768         spin_lock(&tree->lock);
 769         if (cached_state && *cached_state) {
 770                 state = *cached_state;
 771                 if (state->start == start && state->tree) {
 772                         node = &state->rb_node;
 773                         goto hit_next;
 774                 }
 775         }
 776         /*
 777          * this search will find all the extents that end after
 778          * our range starts.
 779          */
 780         node = tree_search(tree, start);
 781         if (!node) {
 782                 err = insert_state(tree, prealloc, start, end, bits);
 783                 prealloc = NULL;
 784                 BUG_ON(err == -EEXIST);
 785                 goto out;
 786         }
 787         state = rb_entry(node, struct extent_state, rb_node);
 788 hit_next:
 789         last_start = state->start;
 790         last_end = state->end;
 791
 792         /*
 793          * | ---- desired range ---- |
 794          * | state |
 795          *
 796          * Just lock what we found and keep going
 797          */
 798         if (state->start == start && state->end <= end) {
 799                 struct rb_node *next_node;
 800                 if (state->state & exclusive_bits) {
 801                         *failed_start = state->start;
 802                         err = -EEXIST;
 803                         goto out;
 804                 }
 805
 806                 err = set_state_bits(tree, state, bits);
 807                 if (err)
 808                         goto out;
 809
 810                 cache_state(state, cached_state);
 811                 merge_state(tree, state);
 812                 if (last_end == (u64)-1)
 813                         goto out;
 814
 815                 start = last_end + 1;
 816                 if (start < end && prealloc && !need_resched()) {
 817                         next_node = rb_next(node);
 818                         if (next_node) {
 819                                 state = rb_entry(next_node, struct extent_state,
 820                                                  rb_node);
 821                                 if (state->start == start)
 822                                         goto hit_next;
 823                         }
 824                 }
 825                 goto search_again;
 826         }
 827
 828         /*
 829          *     | ---- desired range ---- |
 830          * | state |
 831          *   or
 832          * | ------------- state -------------- |
 833          *
 834          * We need to split the extent we found, and may flip bits on
 835          * second half.
 836          *
 837          * If the extent we found extends past our
 838          * range, we just split and search again.  It'll get split
 839          * again the next time though.
 840          *
 841          * If the extent we found is inside our range, we set the
 842          * desired bit on it.
 843          */
 844         if (state->start < start) {
 845                 if (state->state & exclusive_bits) {
 846                         *failed_start = start;
 847                         err = -EEXIST;
 848                         goto out;
 849                 }
 850                 err = split_state(tree, state, prealloc, start);
 851                 BUG_ON(err == -EEXIST);
 852                 prealloc = NULL;
 853                 if (err)
 854                         goto out;
 855                 if (state->end <= end) {
 856                         err = set_state_bits(tree, state, bits);
 857                         if (err)
 858                                 goto out;
 859                         cache_state(state, cached_state);
 860                         merge_state(tree, state);
 861                         if (last_end == (u64)-1)
 862                                 goto out;
 863                         start = last_end + 1;
 864                 }
 865                 goto search_again;
 866         }
 867         /*
 868          * | ---- desired range ---- |
 869          *     | state | or               | state |
 870          *
 871          * There's a hole, we need to insert something in it and
 872          * ignore the extent we found.
 873          */
 874         if (state->start > start) {
 875                 u64 this_end;
 876                 if (end < last_start)
 877                         this_end = end;
 878                 else
 879                         this_end = last_start - 1;
 880                 err = insert_state(tree, prealloc, start, this_end,
 881                                    bits);
 882                 BUG_ON(err == -EEXIST);
 883                 if (err) {
 884                         prealloc = NULL;
 885                         goto out;
 886                 }
 887                 cache_state(prealloc, cached_state);
 888                 prealloc = NULL;
 889                 start = this_end + 1;
 890                 goto search_again;
 891         }
 892         /*
 893          * | ---- desired range ---- |
 894          *                        | state |
 895          * We need to split the extent, and set the bit
 896          * on the first half
 897          */
 898         if (state->start <= end && state->end > end) {
 899                 if (state->state & exclusive_bits) {
 900                         *failed_start = start;
 901                         err = -EEXIST;
 902                         goto out;
 903                 }
 904                 err = split_state(tree, state, prealloc, end + 1);
 905                 BUG_ON(err == -EEXIST);
 906
 907                 err = set_state_bits(tree, prealloc, bits);
 908                 if (err) {
 909                         prealloc = NULL;
 910                         goto out;
 911                 }
 912                 cache_state(prealloc, cached_state);
 913                 merge_state(tree, prealloc);
 914                 prealloc = NULL;
 915                 goto out;
 916         }
 917
 918         goto search_again;
 919
 920 out:
 921         spin_unlock(&tree->lock);
 922         if (prealloc)
 923                 free_extent_state(prealloc);
 924
 925         return err;
 926
 927 search_again:
 928         if (start > end)
 929                 goto out;
 930         spin_unlock(&tree->lock);
 931         if (mask & __GFP_WAIT)
 932                 cond_resched();
 933         goto again;
 934 }
 935
 936 /* wrappers around set/clear extent bit */
 937 int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
 938                      gfp_t mask)
 939 {
 940         return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL,
 941                               NULL, mask);
 942 }
 943
 944 int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 945                     int bits, gfp_t mask)
 946 {
 947         return set_extent_bit(tree, start, end, bits, 0, NULL,
 948                               NULL, mask);
 949 }
 950
 951 int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 952                       int bits, gfp_t mask)
 953 {
 954         return clear_extent_bit(tree, start, end, bits, 0, 0, NULL, mask);
 955 }
 956
 957 int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
 958                         struct extent_state **cached_state, gfp_t mask)
 959 {
 960         return set_extent_bit(tree, start, end,
 961                               EXTENT_DELALLOC | EXTENT_DIRTY | EXTENT_UPTODATE,
 962                               0, NULL, cached_state, mask);
 963 }
 964
 965 int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
 966                        gfp_t mask)
 967 {
 968         return clear_extent_bit(tree, start, end,
 969                                 EXTENT_DIRTY | EXTENT_DELALLOC |
 970                                 EXTENT_DO_ACCOUNTING, 0, 0,
 971                                 NULL, mask);
 972 }
 973
 974 int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
 975                      gfp_t mask)
 976 {
 977         return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL,
 978                               NULL, mask);
 979 }
 980
 981 static int clear_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
 982                        gfp_t mask)
 983 {
 984         return clear_extent_bit(tree, start, end, EXTENT_NEW, 0, 0,
 985                                 NULL, mask);
 986 }
 987
 988 int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
 989                         gfp_t mask)
 990 {
 991         return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL,
 992                               NULL, mask);
 993 }
 994
 995 static int clear_extent_uptodate(struct extent_io_tree *tree, u64 start,
 996                                  u64 end, struct extent_state **cached_state,
 997                                  gfp_t mask)
 998 {
 999         return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
1000                                 cached_state, mask);
1001 }
1002
1003 int wait_on_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1004 {
1005         return wait_extent_bit(tree, start, end, EXTENT_WRITEBACK);
1006 }
1007
1008 /*
1009  * either insert or lock state struct between start and end use mask to tell
1010  * us if waiting is desired.
1011  */
1012 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1013                      int bits, struct extent_state **cached_state, gfp_t mask)
1014 {
1015         int err;
1016         u64 failed_start;
1017         while (1) {
1018                 err = set_extent_bit(tree, start, end, EXTENT_LOCKED | bits,
1019                                      EXTENT_LOCKED, &failed_start,
1020                                      cached_state, mask);
1021                 if (err == -EEXIST && (mask & __GFP_WAIT)) {
1022                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1023                         start = failed_start;
1024                 } else {
1025                         break;
1026                 }
1027                 WARN_ON(start > end);
1028         }
1029         return err;
1030 }
1031
1032 int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
1033 {
1034         return lock_extent_bits(tree, start, end, 0, NULL, mask);
1035 }
1036
1037 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end,
1038                     gfp_t mask)
1039 {
1040         int err;
1041         u64 failed_start;
1042
1043         err = set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1044                              &failed_start, NULL, mask);
1045         if (err == -EEXIST) {
1046                 if (failed_start > start)
1047                         clear_extent_bit(tree, start, failed_start - 1,
1048                                          EXTENT_LOCKED, 1, 0, NULL, mask);
1049                 return 0;
1050         }
1051         return 1;
1052 }
1053
1054 int unlock_extent_cached(struct extent_io_tree *tree, u64 start, u64 end,
1055                          struct extent_state **cached, gfp_t mask)
1056 {
1057         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
1058                                 mask);
1059 }
1060
1061 int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end,
1062                   gfp_t mask)
1063 {
1064         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL,
1065                                 mask);
1066 }
1067
1068 /*
1069  * helper function to set pages and extents in the tree dirty
1070  */
1071 int set_range_dirty(struct extent_io_tree *tree, u64 start, u64 end)
1072 {
1073         unsigned long index = start >> PAGE_CACHE_SHIFT;
1074         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1075         struct page *page;
1076
1077         while (index <= end_index) {
1078                 page = find_get_page(tree->mapping, index);
1079                 BUG_ON(!page);
1080                 __set_page_dirty_nobuffers(page);
1081                 page_cache_release(page);
1082                 index++;
1083         }
1084         return 0;
1085 }
1086
1087 /*
1088  * helper function to set both pages and extents in the tree writeback
1089  */
1090 static int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1091 {
1092         unsigned long index = start >> PAGE_CACHE_SHIFT;
1093         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1094         struct page *page;
1095
1096         while (index <= end_index) {
1097                 page = find_get_page(tree->mapping, index);
1098                 BUG_ON(!page);
1099                 set_page_writeback(page);
1100                 page_cache_release(page);
1101                 index++;
1102         }
1103         return 0;
1104 }
1105
1106 /*
1107  * find the first offset in the io tree with 'bits' set. zero is
1108  * returned if we find something, and *start_ret and *end_ret are
1109  * set to reflect the state struct that was found.
1110  *
1111  * If nothing was found, 1 is returned, < 0 on error
1112  */
1113 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1114                           u64 *start_ret, u64 *end_ret, int bits)
1115 {
1116         struct rb_node *node;
1117         struct extent_state *state;
1118         int ret = 1;
1119
1120         spin_lock(&tree->lock);
1121         /*
1122          * this search will find all the extents that end after
1123          * our range starts.
1124          */
1125         node = tree_search(tree, start);
1126         if (!node)
1127                 goto out;
1128
1129         while (1) {
1130                 state = rb_entry(node, struct extent_state, rb_node);
1131                 if (state->end >= start && (state->state & bits)) {
1132                         *start_ret = state->start;
1133                         *end_ret = state->end;
1134                         ret = 0;
1135                         break;
1136                 }
1137                 node = rb_next(node);
1138                 if (!node)
1139                         break;
1140         }
1141 out:
1142         spin_unlock(&tree->lock);
1143         return ret;
1144 }
1145
1146 /* find the first state struct with 'bits' set after 'start', and
1147  * return it.  tree->lock must be held.  NULL will returned if
1148  * nothing was found after 'start'
1149  */
1150 struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree,
1151                                                  u64 start, int bits)
1152 {
1153         struct rb_node *node;
1154         struct extent_state *state;
1155
1156         /*
1157          * this search will find all the extents that end after
1158          * our range starts.
1159          */
1160         node = tree_search(tree, start);
1161         if (!node)
1162                 goto out;
1163
1164         while (1) {
1165                 state = rb_entry(node, struct extent_state, rb_node);
1166                 if (state->end >= start && (state->state & bits))
1167                         return state;
1168
1169                 node = rb_next(node);
1170                 if (!node)
1171                         break;
1172         }
1173 out:
1174         return NULL;
1175 }
1176
1177 /*
1178  * find a contiguous range of bytes in the file marked as delalloc, not
1179  * more than 'max_bytes'.  start and end are used to return the range,
1180  *
1181  * 1 is returned if we find something, 0 if nothing was in the tree
1182  */
1183 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1184                                         u64 *start, u64 *end, u64 max_bytes,
1185                                         struct extent_state **cached_state)
1186 {
1187         struct rb_node *node;
1188         struct extent_state *state;
1189         u64 cur_start = *start;
1190         u64 found = 0;
1191         u64 total_bytes = 0;
1192
1193         spin_lock(&tree->lock);
1194
1195         /*
1196          * this search will find all the extents that end after
1197          * our range starts.
1198          */
1199         node = tree_search(tree, cur_start);
1200         if (!node) {
1201                 if (!found)
1202                         *end = (u64)-1;
1203                 goto out;
1204         }
1205
1206         while (1) {
1207                 state = rb_entry(node, struct extent_state, rb_node);
1208                 if (found && (state->start != cur_start ||
1209                               (state->state & EXTENT_BOUNDARY))) {
1210                         goto out;
1211                 }
1212                 if (!(state->state & EXTENT_DELALLOC)) {
1213                         if (!found)
1214                                 *end = state->end;
1215                         goto out;
1216                 }
1217                 if (!found) {
1218                         *start = state->start;
1219                         *cached_state = state;
1220                         atomic_inc(&state->refs);
1221                 }
1222                 found++;
1223                 *end = state->end;
1224                 cur_start = state->end + 1;
1225                 node = rb_next(node);
1226                 if (!node)
1227                         break;
1228                 total_bytes += state->end - state->start + 1;
1229                 if (total_bytes >= max_bytes)
1230                         break;
1231         }
1232 out:
1233         spin_unlock(&tree->lock);
1234         return found;
1235 }
1236
1237 static noinline int __unlock_for_delalloc(struct inode *inode,
1238                                           struct page *locked_page,
1239                                           u64 start, u64 end)
1240 {
1241         int ret;
1242         struct page *pages[16];
1243         unsigned long index = start >> PAGE_CACHE_SHIFT;
1244         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1245         unsigned long nr_pages = end_index - index + 1;
1246         int i;
1247
1248         if (index == locked_page->index && end_index == index)
1249                 return 0;
1250
1251         while (nr_pages > 0) {
1252                 ret = find_get_pages_contig(inode->i_mapping, index,
1253                                      min_t(unsigned long, nr_pages,
1254                                      ARRAY_SIZE(pages)), pages);
1255                 for (i = 0; i < ret; i++) {
1256                         if (pages[i] != locked_page)
1257                                 unlock_page(pages[i]);
1258                         page_cache_release(pages[i]);
1259                 }
1260                 nr_pages -= ret;
1261                 index += ret;
1262                 cond_resched();
1263         }
1264         return 0;
1265 }
1266
1267 static noinline int lock_delalloc_pages(struct inode *inode,
1268                                         struct page *locked_page,
1269                                         u64 delalloc_start,
1270                                         u64 delalloc_end)
1271 {
1272         unsigned long index = delalloc_start >> PAGE_CACHE_SHIFT;
1273         unsigned long start_index = index;
1274         unsigned long end_index = delalloc_end >> PAGE_CACHE_SHIFT;
1275         unsigned long pages_locked = 0;
1276         struct page *pages[16];
1277         unsigned long nrpages;
1278         int ret;
1279         int i;
1280
1281         /* the caller is responsible for locking the start index */
1282         if (index == locked_page->index && index == end_index)
1283                 return 0;
1284
1285         /* skip the page at the start index */
1286         nrpages = end_index - index + 1;
1287         while (nrpages > 0) {
1288                 ret = find_get_pages_contig(inode->i_mapping, index,
1289                                      min_t(unsigned long,
1290                                      nrpages, ARRAY_SIZE(pages)), pages);
1291                 if (ret == 0) {
1292                         ret = -EAGAIN;
1293                         goto done;
1294                 }
1295                 /* now we have an array of pages, lock them all */
1296                 for (i = 0; i < ret; i++) {
1297                         /*
1298                          * the caller is taking responsibility for
1299                          * locked_page
1300                          */
1301                         if (pages[i] != locked_page) {
1302                                 lock_page(pages[i]);
1303                                 if (!PageDirty(pages[i]) ||
1304                                     pages[i]->mapping != inode->i_mapping) {
1305                                         ret = -EAGAIN;
1306                                         unlock_page(pages[i]);
1307                                         page_cache_release(pages[i]);
1308                                         goto done;
1309                                 }
1310                         }
1311                         page_cache_release(pages[i]);
1312                         pages_locked++;
1313                 }
1314                 nrpages -= ret;
1315                 index += ret;
1316                 cond_resched();
1317         }
1318         ret = 0;
1319 done:
1320         if (ret && pages_locked) {
1321                 __unlock_for_delalloc(inode, locked_page,
1322                               delalloc_start,
1323                               ((u64)(start_index + pages_locked - 1)) <<
1324                               PAGE_CACHE_SHIFT);
1325         }
1326         return ret;
1327 }
1328
1329 /*
1330  * find a contiguous range of bytes in the file marked as delalloc, not
1331  * more than 'max_bytes'.  start and end are used to return the range,
1332  *
1333  * 1 is returned if we find something, 0 if nothing was in the tree
1334  */
1335 static noinline u64 find_lock_delalloc_range(struct inode *inode,
1336                                              struct extent_io_tree *tree,
1337                                              struct page *locked_page,
1338                                              u64 *start, u64 *end,
1339                                              u64 max_bytes)
1340 {
1341         u64 delalloc_start;
1342         u64 delalloc_end;
1343         u64 found;
1344         struct extent_state *cached_state = NULL;
1345         int ret;
1346         int loops = 0;
1347
1348 again:
1349         /* step one, find a bunch of delalloc bytes starting at start */
1350         delalloc_start = *start;
1351         delalloc_end = 0;
1352         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1353                                     max_bytes, &cached_state);
1354         if (!found || delalloc_end <= *start) {
1355                 *start = delalloc_start;
1356                 *end = delalloc_end;
1357                 free_extent_state(cached_state);
1358                 return found;
1359         }
1360
1361         /*
1362          * start comes from the offset of locked_page.  We have to lock
1363          * pages in order, so we can't process delalloc bytes before
1364          * locked_page
1365          */
1366         if (delalloc_start < *start)
1367                 delalloc_start = *start;
1368
1369         /*
1370          * make sure to limit the number of pages we try to lock down
1371          * if we're looping.
1372          */
1373         if (delalloc_end + 1 - delalloc_start > max_bytes && loops)
1374                 delalloc_end = delalloc_start + PAGE_CACHE_SIZE - 1;
1375
1376         /* step two, lock all the pages after the page that has start */
1377         ret = lock_delalloc_pages(inode, locked_page,
1378                                   delalloc_start, delalloc_end);
1379         if (ret == -EAGAIN) {
1380                 /* some of the pages are gone, lets avoid looping by
1381                  * shortening the size of the delalloc range we're searching
1382                  */
1383                 free_extent_state(cached_state);
1384                 if (!loops) {
1385                         unsigned long offset = (*start) & (PAGE_CACHE_SIZE - 1);
1386                         max_bytes = PAGE_CACHE_SIZE - offset;
1387                         loops = 1;
1388                         goto again;
1389                 } else {
1390                         found = 0;
1391                         goto out_failed;
1392                 }
1393         }
1394         BUG_ON(ret);
1395
1396         /* step three, lock the state bits for the whole range */
1397         lock_extent_bits(tree, delalloc_start, delalloc_end,
1398                          0, &cached_state, GFP_NOFS);
1399
1400         /* then test to make sure it is all still delalloc */
1401         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1402                              EXTENT_DELALLOC, 1, cached_state);
1403         if (!ret) {
1404                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1405                                      &cached_state, GFP_NOFS);
1406                 __unlock_for_delalloc(inode, locked_page,
1407                               delalloc_start, delalloc_end);
1408                 cond_resched();
1409                 goto again;
1410         }
1411         free_extent_state(cached_state);
1412         *start = delalloc_start;
1413         *end = delalloc_end;
1414 out_failed:
1415         return found;
1416 }
1417
1418 int extent_clear_unlock_delalloc(struct inode *inode,
1419                                 struct extent_io_tree *tree,
1420                                 u64 start, u64 end, struct page *locked_page,
1421                                 unsigned long op)
1422 {
1423         int ret;
1424         struct page *pages[16];
1425         unsigned long index = start >> PAGE_CACHE_SHIFT;
1426         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1427         unsigned long nr_pages = end_index - index + 1;
1428         int i;
1429         int clear_bits = 0;
1430
1431         if (op & EXTENT_CLEAR_UNLOCK)
1432                 clear_bits |= EXTENT_LOCKED;
1433         if (op & EXTENT_CLEAR_DIRTY)
1434                 clear_bits |= EXTENT_DIRTY;
1435
1436         if (op & EXTENT_CLEAR_DELALLOC)
1437                 clear_bits |= EXTENT_DELALLOC;
1438
1439         if (op & EXTENT_CLEAR_ACCOUNTING)
1440                 clear_bits |= EXTENT_DO_ACCOUNTING;
1441
1442         clear_extent_bit(tree, start, end, clear_bits, 1, 0, NULL, GFP_NOFS);
1443         if (!(op & (EXTENT_CLEAR_UNLOCK_PAGE | EXTENT_CLEAR_DIRTY |
1444                     EXTENT_SET_WRITEBACK | EXTENT_END_WRITEBACK |
1445                     EXTENT_SET_PRIVATE2)))
1446                 return 0;
1447
1448         while (nr_pages > 0) {
1449                 ret = find_get_pages_contig(inode->i_mapping, index,
1450                                      min_t(unsigned long,
1451                                      nr_pages, ARRAY_SIZE(pages)), pages);
1452                 for (i = 0; i < ret; i++) {
1453
1454                         if (op & EXTENT_SET_PRIVATE2)
1455                                 SetPagePrivate2(pages[i]);
1456
1457                         if (pages[i] == locked_page) {
1458                                 page_cache_release(pages[i]);
1459                                 continue;
1460                         }
1461                         if (op & EXTENT_CLEAR_DIRTY)
1462                                 clear_page_dirty_for_io(pages[i]);
1463                         if (op & EXTENT_SET_WRITEBACK)
1464                                 set_page_writeback(pages[i]);
1465                         if (op & EXTENT_END_WRITEBACK)
1466                                 end_page_writeback(pages[i]);
1467                         if (op & EXTENT_CLEAR_UNLOCK_PAGE)
1468                                 unlock_page(pages[i]);
1469                         page_cache_release(pages[i]);
1470                 }
1471                 nr_pages -= ret;
1472                 index += ret;
1473                 cond_resched();
1474         }
1475         return 0;
1476 }
1477
1478 /*
1479  * count the number of bytes in the tree that have a given bit(s)
1480  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1481  * cached.  The total number found is returned.
1482  */
1483 u64 count_range_bits(struct extent_io_tree *tree,
1484                      u64 *start, u64 search_end, u64 max_bytes,
1485                      unsigned long bits)
1486 {
1487         struct rb_node *node;
1488         struct extent_state *state;
1489         u64 cur_start = *start;
1490         u64 total_bytes = 0;
1491         int found = 0;
1492
1493         if (search_end <= cur_start) {
1494                 WARN_ON(1);
1495                 return 0;
1496         }
1497
1498         spin_lock(&tree->lock);
1499         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1500                 total_bytes = tree->dirty_bytes;
1501                 goto out;
1502         }
1503         /*
1504          * this search will find all the extents that end after
1505          * our range starts.
1506          */
1507         node = tree_search(tree, cur_start);
1508         if (!node)
1509                 goto out;
1510
1511         while (1) {
1512                 state = rb_entry(node, struct extent_state, rb_node);
1513                 if (state->start > search_end)
1514                         break;
1515                 if (state->end >= cur_start && (state->state & bits)) {
1516                         total_bytes += min(search_end, state->end) + 1 -
1517                                        max(cur_start, state->start);
1518                         if (total_bytes >= max_bytes)
1519                                 break;
1520                         if (!found) {
1521                                 *start = state->start;
1522                                 found = 1;
1523                         }
1524                 }
1525                 node = rb_next(node);
1526                 if (!node)
1527                         break;
1528         }
1529 out:
1530         spin_unlock(&tree->lock);
1531         return total_bytes;
1532 }
1533
1534 /*
1535  * set the private field for a given byte offset in the tree.  If there isn't
1536  * an extent_state there already, this does nothing.
1537  */
1538 int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
1539 {
1540         struct rb_node *node;
1541         struct extent_state *state;
1542         int ret = 0;
1543
1544         spin_lock(&tree->lock);
1545         /*
1546          * this search will find all the extents that end after
1547          * our range starts.
1548          */
1549         node = tree_search(tree, start);
1550         if (!node) {
1551                 ret = -ENOENT;
1552                 goto out;
1553         }
1554         state = rb_entry(node, struct extent_state, rb_node);
1555         if (state->start != start) {
1556                 ret = -ENOENT;
1557                 goto out;
1558         }
1559         state->private = private;
1560 out:
1561         spin_unlock(&tree->lock);
1562         return ret;
1563 }
1564
1565 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
1566 {
1567         struct rb_node *node;
1568         struct extent_state *state;
1569         int ret = 0;
1570
1571         spin_lock(&tree->lock);
1572         /*
1573          * this search will find all the extents that end after
1574          * our range starts.
1575          */
1576         node = tree_search(tree, start);
1577         if (!node) {
1578                 ret = -ENOENT;
1579                 goto out;
1580         }
1581         state = rb_entry(node, struct extent_state, rb_node);
1582         if (state->start != start) {
1583                 ret = -ENOENT;
1584                 goto out;
1585         }
1586         *private = state->private;
1587 out:
1588         spin_unlock(&tree->lock);
1589         return ret;
1590 }
1591
1592 /*
1593  * searches a range in the state tree for a given mask.
1594  * If 'filled' == 1, this returns 1 only if every extent in the tree
1595  * has the bits set.  Otherwise, 1 is returned if any bit in the
1596  * range is found set.
1597  */
1598 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1599                    int bits, int filled, struct extent_state *cached)
1600 {
1601         struct extent_state *state = NULL;
1602         struct rb_node *node;
1603         int bitset = 0;
1604
1605         spin_lock(&tree->lock);
1606         if (cached && cached->tree && cached->start == start)
1607                 node = &cached->rb_node;
1608         else
1609                 node = tree_search(tree, start);
1610         while (node && start <= end) {
1611                 state = rb_entry(node, struct extent_state, rb_node);
1612
1613                 if (filled && state->start > start) {
1614                         bitset = 0;
1615                         break;
1616                 }
1617
1618                 if (state->start > end)
1619                         break;
1620
1621                 if (state->state & bits) {
1622                         bitset = 1;
1623                         if (!filled)
1624                                 break;
1625                 } else if (filled) {
1626                         bitset = 0;
1627                         break;
1628                 }
1629
1630                 if (state->end == (u64)-1)
1631                         break;
1632
1633                 start = state->end + 1;
1634                 if (start > end)
1635                         break;
1636                 node = rb_next(node);
1637                 if (!node) {
1638                         if (filled)
1639                                 bitset = 0;
1640                         break;
1641                 }
1642         }
1643         spin_unlock(&tree->lock);
1644         return bitset;
1645 }
1646
1647 /*
1648  * helper function to set a given page up to date if all the
1649  * extents in the tree for that page are up to date
1650  */
1651 static int check_page_uptodate(struct extent_io_tree *tree,
1652                                struct page *page)
1653 {
1654         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1655         u64 end = start + PAGE_CACHE_SIZE - 1;
1656         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
1657                 SetPageUptodate(page);
1658         return 0;
1659 }
1660
1661 /*
1662  * helper function to unlock a page if all the extents in the tree
1663  * for that page are unlocked
1664  */
1665 static int check_page_locked(struct extent_io_tree *tree,
1666                              struct page *page)
1667 {
1668         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
1669         u64 end = start + PAGE_CACHE_SIZE - 1;
1670         if (!test_range_bit(tree, start, end, EXTENT_LOCKED, 0, NULL))
1671                 unlock_page(page);
1672         return 0;
1673 }
1674
1675 /*
1676  * helper function to end page writeback if all the extents
1677  * in the tree for that page are done with writeback
1678  */
1679 static int check_page_writeback(struct extent_io_tree *tree,
1680                              struct page *page)
1681 {
1682         end_page_writeback(page);
1683         return 0;
1684 }
1685
1686 /* lots and lots of room for performance fixes in the end_bio funcs */
1687
1688 /*
1689  * after a writepage IO is done, we need to:
1690  * clear the uptodate bits on error
1691  * clear the writeback bits in the extent tree for this IO
1692  * end_page_writeback if the page has no more pending IO
1693  *
1694  * Scheduling is not allowed, so the extent state tree is expected
1695  * to have one and only one object corresponding to this IO.
1696  */
1697 static void end_bio_extent_writepage(struct bio *bio, int err)
1698 {
1699         int uptodate = err == 0;
1700         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1701         struct extent_io_tree *tree;
1702         u64 start;
1703         u64 end;
1704         int whole_page;
1705         int ret;
1706
1707         do {
1708                 struct page *page = bvec->bv_page;
1709                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1710
1711                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1712                          bvec->bv_offset;
1713                 end = start + bvec->bv_len - 1;
1714
1715                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
1716                         whole_page = 1;
1717                 else
1718                         whole_page = 0;
1719
1720                 if (--bvec >= bio->bi_io_vec)
1721                         prefetchw(&bvec->bv_page->flags);
1722                 if (tree->ops && tree->ops->writepage_end_io_hook) {
1723                         ret = tree->ops->writepage_end_io_hook(page, start,
1724                                                        end, NULL, uptodate);
1725                         if (ret)
1726                                 uptodate = 0;
1727                 }
1728
1729                 if (!uptodate && tree->ops &&
1730                     tree->ops->writepage_io_failed_hook) {
1731                         ret = tree->ops->writepage_io_failed_hook(bio, page,
1732                                                          start, end, NULL);
1733                         if (ret == 0) {
1734                                 uptodate = (err == 0);
1735                                 continue;
1736                         }
1737                 }
1738
1739                 if (!uptodate) {
1740                         clear_extent_uptodate(tree, start, end, NULL, GFP_NOFS);
1741                         ClearPageUptodate(page);
1742                         SetPageError(page);
1743                 }
1744
1745                 if (whole_page)
1746                         end_page_writeback(page);
1747                 else
1748                         check_page_writeback(tree, page);
1749         } while (bvec >= bio->bi_io_vec);
1750
1751         bio_put(bio);
1752 }
1753
1754 /*
1755  * after a readpage IO is done, we need to:
1756  * clear the uptodate bits on error
1757  * set the uptodate bits if things worked
1758  * set the page up to date if all extents in the tree are uptodate
1759  * clear the lock bit in the extent tree
1760  * unlock the page if there are no other extents locked for it
1761  *
1762  * Scheduling is not allowed, so the extent state tree is expected
1763  * to have one and only one object corresponding to this IO.
1764  */
1765 static void end_bio_extent_readpage(struct bio *bio, int err)
1766 {
1767         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1768         struct bio_vec *bvec_end = bio->bi_io_vec + bio->bi_vcnt - 1;
1769         struct bio_vec *bvec = bio->bi_io_vec;
1770         struct extent_io_tree *tree;
1771         u64 start;
1772         u64 end;
1773         int whole_page;
1774         int ret;
1775
1776         if (err)
1777                 uptodate = 0;
1778
1779         do {
1780                 struct page *page = bvec->bv_page;
1781                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1782
1783                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1784                         bvec->bv_offset;
1785                 end = start + bvec->bv_len - 1;
1786
1787                 if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
1788                         whole_page = 1;
1789                 else
1790                         whole_page = 0;
1791
1792                 if (++bvec <= bvec_end)
1793                         prefetchw(&bvec->bv_page->flags);
1794
1795                 if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
1796                         ret = tree->ops->readpage_end_io_hook(page, start, end,
1797                                                               NULL);
1798                         if (ret)
1799                                 uptodate = 0;
1800                 }
1801                 if (!uptodate && tree->ops &&
1802                     tree->ops->readpage_io_failed_hook) {
1803                         ret = tree->ops->readpage_io_failed_hook(bio, page,
1804                                                          start, end, NULL);
1805                         if (ret == 0) {
1806                                 uptodate =
1807                                         test_bit(BIO_UPTODATE, &bio->bi_flags);
1808                                 if (err)
1809                                         uptodate = 0;
1810                                 continue;
1811                         }
1812                 }
1813
1814                 if (uptodate) {
1815                         set_extent_uptodate(tree, start, end,
1816                                             GFP_ATOMIC);
1817                 }
1818                 unlock_extent(tree, start, end, GFP_ATOMIC);
1819
1820                 if (whole_page) {
1821                         if (uptodate) {
1822                                 SetPageUptodate(page);
1823                         } else {
1824                                 ClearPageUptodate(page);
1825                                 SetPageError(page);
1826                         }
1827                         unlock_page(page);
1828                 } else {
1829                         if (uptodate) {
1830                                 check_page_uptodate(tree, page);
1831                         } else {
1832                                 ClearPageUptodate(page);
1833                                 SetPageError(page);
1834                         }
1835                         check_page_locked(tree, page);
1836                 }
1837         } while (bvec <= bvec_end);
1838
1839         bio_put(bio);
1840 }
1841
1842 /*
1843  * IO done from prepare_write is pretty simple, we just unlock
1844  * the structs in the extent tree when done, and set the uptodate bits
1845  * as appropriate.
1846  */
1847 static void end_bio_extent_preparewrite(struct bio *bio, int err)
1848 {
1849         const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1850         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1851         struct extent_io_tree *tree;
1852         u64 start;
1853         u64 end;
1854
1855         do {
1856                 struct page *page = bvec->bv_page;
1857                 tree = &BTRFS_I(page->mapping->host)->io_tree;
1858
1859                 start = ((u64)page->index << PAGE_CACHE_SHIFT) +
1860                         bvec->bv_offset;
1861                 end = start + bvec->bv_len - 1;
1862
1863                 if (--bvec >= bio->bi_io_vec)
1864                         prefetchw(&bvec->bv_page->flags);
1865
1866                 if (uptodate) {
1867                         set_extent_uptodate(tree, start, end, GFP_ATOMIC);
1868                 } else {
1869                         ClearPageUptodate(page);
1870                         SetPageError(page);
1871                 }
1872
1873                 unlock_extent(tree, start, end, GFP_ATOMIC);
1874
1875         } while (bvec >= bio->bi_io_vec);
1876
1877         bio_put(bio);
1878 }
1879
1880 static struct bio *
1881 extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
1882                  gfp_t gfp_flags)
1883 {
1884         struct bio *bio;
1885
1886         bio = bio_alloc(gfp_flags, nr_vecs);
1887
1888         if (bio == NULL && (current->flags & PF_MEMALLOC)) {
1889                 while (!bio && (nr_vecs /= 2))
1890                         bio = bio_alloc(gfp_flags, nr_vecs);
1891         }
1892
1893         if (bio) {
1894                 bio->bi_size = 0;
1895                 bio->bi_bdev = bdev;
1896                 bio->bi_sector = first_sector;
1897         }
1898         return bio;
1899 }
1900
1901 static int submit_one_bio(int rw, struct bio *bio, int mirror_num,
1902                           unsigned long bio_flags)
1903 {
1904         int ret = 0;
1905         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1906         struct page *page = bvec->bv_page;
1907         struct extent_io_tree *tree = bio->bi_private;
1908         u64 start;
1909         u64 end;
1910
1911         start = ((u64)page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset;
1912         end = start + bvec->bv_len - 1;
1913
1914         bio->bi_private = NULL;
1915
1916         bio_get(bio);
1917
1918         if (tree->ops && tree->ops->submit_bio_hook)
1919                 tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
1920                                            mirror_num, bio_flags);
1921         else
1922                 submit_bio(rw, bio);
1923         if (bio_flagged(bio, BIO_EOPNOTSUPP))
1924                 ret = -EOPNOTSUPP;
1925         bio_put(bio);
1926         return ret;
1927 }
1928
1929 static int submit_extent_page(int rw, struct extent_io_tree *tree,
1930                               struct page *page, sector_t sector,
1931                               size_t size, unsigned long offset,
1932                               struct block_device *bdev,
1933                               struct bio **bio_ret,
1934                               unsigned long max_pages,
1935                               bio_end_io_t end_io_func,
1936                               int mirror_num,
1937                               unsigned long prev_bio_flags,
1938                               unsigned long bio_flags)
1939 {
1940         int ret = 0;
1941         struct bio *bio;
1942         int nr;
1943         int contig = 0;
1944         int this_compressed = bio_flags & EXTENT_BIO_COMPRESSED;
1945         int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
1946         size_t page_size = min_t(size_t, size, PAGE_CACHE_SIZE);
1947
1948         if (bio_ret && *bio_ret) {
1949                 bio = *bio_ret;
1950                 if (old_compressed)
1951                         contig = bio->bi_sector == sector;
1952                 else
1953                         contig = bio->bi_sector + (bio->bi_size >> 9) ==
1954                                 sector;
1955
1956                 if (prev_bio_flags != bio_flags || !contig ||
1957                     (tree->ops && tree->ops->merge_bio_hook &&
1958                      tree->ops->merge_bio_hook(page, offset, page_size, bio,
1959                                                bio_flags)) ||
1960                     bio_add_page(bio, page, page_size, offset) < page_size) {
1961                         ret = submit_one_bio(rw, bio, mirror_num,
1962                                              prev_bio_flags);
1963                         bio = NULL;
1964                 } else {
1965                         return 0;
1966                 }
1967         }
1968         if (this_compressed)
1969                 nr = BIO_MAX_PAGES;
1970         else
1971                 nr = bio_get_nr_vecs(bdev);
1972
1973         bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
1974
1975         bio_add_page(bio, page, page_size, offset);
1976         bio->bi_end_io = end_io_func;
1977         bio->bi_private = tree;
1978
1979         if (bio_ret)
1980                 *bio_ret = bio;
1981         else
1982                 ret = submit_one_bio(rw, bio, mirror_num, bio_flags);
1983
1984         return ret;
1985 }
1986
1987 void set_page_extent_mapped(struct page *page)
1988 {
1989         if (!PagePrivate(page)) {
1990                 SetPagePrivate(page);
1991                 page_cache_get(page);
1992                 set_page_private(page, EXTENT_PAGE_PRIVATE);
1993         }
1994 }
1995
1996 static void set_page_extent_head(struct page *page, unsigned long len)
1997 {
1998         set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);
1999 }
2000
2001 /*
2002  * basic readpage implementation.  Locked extent state structs are inserted
2003  * into the tree that are removed when the IO is done (by the end_io
2004  * handlers)
2005  */
2006 static int __extent_read_full_page(struct extent_io_tree *tree,
2007                                    struct page *page,
2008                                    get_extent_t *get_extent,
2009                                    struct bio **bio, int mirror_num,
2010                                    unsigned long *bio_flags)
2011 {
2012         struct inode *inode = page->mapping->host;
2013         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2014         u64 page_end = start + PAGE_CACHE_SIZE - 1;
2015         u64 end;
2016         u64 cur = start;
2017         u64 extent_offset;
2018         u64 last_byte = i_size_read(inode);
2019         u64 block_start;
2020         u64 cur_end;
2021         sector_t sector;
2022         struct extent_map *em;
2023         struct block_device *bdev;
2024         int ret;
2025         int nr = 0;
2026         size_t page_offset = 0;
2027         size_t iosize;
2028         size_t disk_io_size;
2029         size_t blocksize = inode->i_sb->s_blocksize;
2030         unsigned long this_bio_flag = 0;
2031
2032         set_page_extent_mapped(page);
2033
2034         end = page_end;
2035         lock_extent(tree, start, end, GFP_NOFS);
2036
2037         if (page->index == last_byte >> PAGE_CACHE_SHIFT) {
2038                 char *userpage;
2039                 size_t zero_offset = last_byte & (PAGE_CACHE_SIZE - 1);
2040
2041                 if (zero_offset) {
2042                         iosize = PAGE_CACHE_SIZE - zero_offset;
2043                         userpage = kmap_atomic(page, KM_USER0);
2044                         memset(userpage + zero_offset, 0, iosize);
2045                         flush_dcache_page(page);
2046                         kunmap_atomic(userpage, KM_USER0);
2047                 }
2048         }
2049         while (cur <= end) {
2050                 if (cur >= last_byte) {
2051                         char *userpage;
2052                         iosize = PAGE_CACHE_SIZE - page_offset;
2053                         userpage = kmap_atomic(page, KM_USER0);
2054                         memset(userpage + page_offset, 0, iosize);
2055                         flush_dcache_page(page);
2056                         kunmap_atomic(userpage, KM_USER0);
2057                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2058                                             GFP_NOFS);
2059                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2060                         break;
2061                 }
2062                 em = get_extent(inode, page, page_offset, cur,
2063                                 end - cur + 1, 0);
2064                 if (IS_ERR(em) || !em) {
2065                         SetPageError(page);
2066                         unlock_extent(tree, cur, end, GFP_NOFS);
2067                         break;
2068                 }
2069                 extent_offset = cur - em->start;
2070                 BUG_ON(extent_map_end(em) <= cur);
2071                 BUG_ON(end < cur);
2072
2073                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
2074                         this_bio_flag = EXTENT_BIO_COMPRESSED;
2075
2076                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2077                 cur_end = min(extent_map_end(em) - 1, end);
2078                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
2079                 if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
2080                         disk_io_size = em->block_len;
2081                         sector = em->block_start >> 9;
2082                 } else {
2083                         sector = (em->block_start + extent_offset) >> 9;
2084                         disk_io_size = iosize;
2085                 }
2086                 bdev = em->bdev;
2087                 block_start = em->block_start;
2088                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2089                         block_start = EXTENT_MAP_HOLE;
2090                 free_extent_map(em);
2091                 em = NULL;
2092
2093                 /* we've found a hole, just zero and go on */
2094                 if (block_start == EXTENT_MAP_HOLE) {
2095                         char *userpage;
2096                         userpage = kmap_atomic(page, KM_USER0);
2097                         memset(userpage + page_offset, 0, iosize);
2098                         flush_dcache_page(page);
2099                         kunmap_atomic(userpage, KM_USER0);
2100
2101                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2102                                             GFP_NOFS);
2103                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2104                         cur = cur + iosize;
2105                         page_offset += iosize;
2106                         continue;
2107                 }
2108                 /* the get_extent function already copied into the page */
2109                 if (test_range_bit(tree, cur, cur_end,
2110                                    EXTENT_UPTODATE, 1, NULL)) {
2111                         check_page_uptodate(tree, page);
2112                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2113                         cur = cur + iosize;
2114                         page_offset += iosize;
2115                         continue;
2116                 }
2117                 /* we have an inline extent but it didn't get marked up
2118                  * to date.  Error out
2119                  */
2120                 if (block_start == EXTENT_MAP_INLINE) {
2121                         SetPageError(page);
2122                         unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
2123                         cur = cur + iosize;
2124                         page_offset += iosize;
2125                         continue;
2126                 }
2127
2128                 ret = 0;
2129                 if (tree->ops && tree->ops->readpage_io_hook) {
2130                         ret = tree->ops->readpage_io_hook(page, cur,
2131                                                           cur + iosize - 1);
2132                 }
2133                 if (!ret) {
2134                         unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
2135                         pnr -= page->index;
2136                         ret = submit_extent_page(READ, tree, page,
2137                                          sector, disk_io_size, page_offset,
2138                                          bdev, bio, pnr,
2139                                          end_bio_extent_readpage, mirror_num,
2140                                          *bio_flags,
2141                                          this_bio_flag);
2142                         nr++;
2143                         *bio_flags = this_bio_flag;
2144                 }
2145                 if (ret)
2146                         SetPageError(page);
2147                 cur = cur + iosize;
2148                 page_offset += iosize;
2149         }
2150         if (!nr) {
2151                 if (!PageError(page))
2152                         SetPageUptodate(page);
2153                 unlock_page(page);
2154         }
2155         return 0;
2156 }
2157
2158 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
2159                             get_extent_t *get_extent)
2160 {
2161         struct bio *bio = NULL;
2162         unsigned long bio_flags = 0;
2163         int ret;
2164
2165         ret = __extent_read_full_page(tree, page, get_extent, &bio, 0,
2166                                       &bio_flags);
2167         if (bio)
2168                 submit_one_bio(READ, bio, 0, bio_flags);
2169         return ret;
2170 }
2171
2172 static noinline void update_nr_written(struct page *page,
2173                                       struct writeback_control *wbc,
2174                                       unsigned long nr_written)
2175 {
2176         wbc->nr_to_write -= nr_written;
2177         if (wbc->range_cyclic || (wbc->nr_to_write > 0 &&
2178             wbc->range_start == 0 && wbc->range_end == LLONG_MAX))
2179                 page->mapping->writeback_index = page->index + nr_written;
2180 }
2181
2182 /*
2183  * the writepage semantics are similar to regular writepage.  extent
2184  * records are inserted to lock ranges in the tree, and as dirty areas
2185  * are found, they are marked writeback.  Then the lock bits are removed
2186  * and the end_io handler clears the writeback ranges
2187  */
2188 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
2189                               void *data)
2190 {
2191         struct inode *inode = page->mapping->host;
2192         struct extent_page_data *epd = data;
2193         struct extent_io_tree *tree = epd->tree;
2194         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2195         u64 delalloc_start;
2196         u64 page_end = start + PAGE_CACHE_SIZE - 1;
2197         u64 end;
2198         u64 cur = start;
2199         u64 extent_offset;
2200         u64 last_byte = i_size_read(inode);
2201         u64 block_start;
2202         u64 iosize;
2203         u64 unlock_start;
2204         sector_t sector;
2205         struct extent_state *cached_state = NULL;
2206         struct extent_map *em;
2207         struct block_device *bdev;
2208         int ret;
2209         int nr = 0;
2210         size_t pg_offset = 0;
2211         size_t blocksize;
2212         loff_t i_size = i_size_read(inode);
2213         unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
2214         u64 nr_delalloc;
2215         u64 delalloc_end;
2216         int page_started;
2217         int compressed;
2218         int write_flags;
2219         unsigned long nr_written = 0;
2220
2221         if (wbc->sync_mode == WB_SYNC_ALL)
2222                 write_flags = WRITE_SYNC_PLUG;
2223         else
2224                 write_flags = WRITE;
2225
2226         WARN_ON(!PageLocked(page));
2227         pg_offset = i_size & (PAGE_CACHE_SIZE - 1);
2228         if (page->index > end_index ||
2229            (page->index == end_index && !pg_offset)) {
2230                 page->mapping->a_ops->invalidatepage(page, 0);
2231                 unlock_page(page);
2232                 return 0;
2233         }
2234
2235         if (page->index == end_index) {
2236                 char *userpage;
2237
2238                 userpage = kmap_atomic(page, KM_USER0);
2239                 memset(userpage + pg_offset, 0,
2240                        PAGE_CACHE_SIZE - pg_offset);
2241                 kunmap_atomic(userpage, KM_USER0);
2242                 flush_dcache_page(page);
2243         }
2244         pg_offset = 0;
2245
2246         set_page_extent_mapped(page);
2247
2248         delalloc_start = start;
2249         delalloc_end = 0;
2250         page_started = 0;
2251         if (!epd->extent_locked) {
2252                 u64 delalloc_to_write = 0;
2253                 /*
2254                  * make sure the wbc mapping index is at least updated
2255                  * to this page.
2256                  */
2257                 update_nr_written(page, wbc, 0);
2258
2259                 while (delalloc_end < page_end) {
2260                         nr_delalloc = find_lock_delalloc_range(inode, tree,
2261                                                        page,
2262                                                        &delalloc_start,
2263                                                        &delalloc_end,
2264                                                        128 * 1024 * 1024);
2265                         if (nr_delalloc == 0) {
2266                                 delalloc_start = delalloc_end + 1;
2267                                 continue;
2268                         }
2269                         tree->ops->fill_delalloc(inode, page, delalloc_start,
2270                                                  delalloc_end, &page_started,
2271                                                  &nr_written);
2272                         /*
2273                          * delalloc_end is already one less than the total
2274                          * length, so we don't subtract one from
2275                          * PAGE_CACHE_SIZE
2276                          */
2277                         delalloc_to_write += (delalloc_end - delalloc_start +
2278                                               PAGE_CACHE_SIZE) >>
2279                                               PAGE_CACHE_SHIFT;
2280                         delalloc_start = delalloc_end + 1;
2281                 }
2282                 if (wbc->nr_to_write < delalloc_to_write) {
2283                         int thresh = 8192;
2284
2285                         if (delalloc_to_write < thresh * 2)
2286                                 thresh = delalloc_to_write;
2287                         wbc->nr_to_write = min_t(u64, delalloc_to_write,
2288                                                  thresh);
2289                 }
2290
2291                 /* did the fill delalloc function already unlock and start
2292                  * the IO?
2293                  */
2294                 if (page_started) {
2295                         ret = 0;
2296                         /*
2297                          * we've unlocked the page, so we can't update
2298                          * the mapping's writeback index, just update
2299                          * nr_to_write.
2300                          */
2301                         wbc->nr_to_write -= nr_written;
2302                         goto done_unlocked;
2303                 }
2304         }
2305         if (tree->ops && tree->ops->writepage_start_hook) {
2306                 ret = tree->ops->writepage_start_hook(page, start,
2307                                                       page_end);
2308                 if (ret == -EAGAIN) {
2309                         redirty_page_for_writepage(wbc, page);
2310                         update_nr_written(page, wbc, nr_written);
2311                         unlock_page(page);
2312                         ret = 0;
2313                         goto done_unlocked;
2314                 }
2315         }
2316
2317         /*
2318          * we don't want to touch the inode after unlocking the page,
2319          * so we update the mapping writeback index now
2320          */
2321         update_nr_written(page, wbc, nr_written + 1);
2322
2323         end = page_end;
2324         if (last_byte <= start) {
2325                 if (tree->ops && tree->ops->writepage_end_io_hook)
2326                         tree->ops->writepage_end_io_hook(page, start,
2327                                                          page_end, NULL, 1);
2328                 unlock_start = page_end + 1;
2329                 goto done;
2330         }
2331
2332         blocksize = inode->i_sb->s_blocksize;
2333
2334         while (cur <= end) {
2335                 if (cur >= last_byte) {
2336                         if (tree->ops && tree->ops->writepage_end_io_hook)
2337                                 tree->ops->writepage_end_io_hook(page, cur,
2338                                                          page_end, NULL, 1);
2339                         unlock_start = page_end + 1;
2340                         break;
2341                 }
2342                 em = epd->get_extent(inode, page, pg_offset, cur,
2343                                      end - cur + 1, 1);
2344                 if (IS_ERR(em) || !em) {
2345                         SetPageError(page);
2346                         break;
2347                 }
2348
2349                 extent_offset = cur - em->start;
2350                 BUG_ON(extent_map_end(em) <= cur);
2351                 BUG_ON(end < cur);
2352                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2353                 iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
2354                 sector = (em->block_start + extent_offset) >> 9;
2355                 bdev = em->bdev;
2356                 block_start = em->block_start;
2357                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
2358                 free_extent_map(em);
2359                 em = NULL;
2360
2361                 /*
2362                  * compressed and inline extents are written through other
2363                  * paths in the FS
2364                  */
2365                 if (compressed || block_start == EXTENT_MAP_HOLE ||
2366                     block_start == EXTENT_MAP_INLINE) {
2367                         /*
2368                          * end_io notification does not happen here for
2369                          * compressed extents
2370                          */
2371                         if (!compressed && tree->ops &&
2372                             tree->ops->writepage_end_io_hook)
2373                                 tree->ops->writepage_end_io_hook(page, cur,
2374                                                          cur + iosize - 1,
2375                                                          NULL, 1);
2376                         else if (compressed) {
2377                                 /* we don't want to end_page_writeback on
2378                                  * a compressed extent.  this happens
2379                                  * elsewhere
2380                                  */
2381                                 nr++;
2382                         }
2383
2384                         cur += iosize;
2385                         pg_offset += iosize;
2386                         unlock_start = cur;
2387                         continue;
2388                 }
2389                 /* leave this out until we have a page_mkwrite call */
2390                 if (0 && !test_range_bit(tree, cur, cur + iosize - 1,
2391                                    EXTENT_DIRTY, 0, NULL)) {
2392                         cur = cur + iosize;
2393                         pg_offset += iosize;
2394                         continue;
2395                 }
2396
2397                 if (tree->ops && tree->ops->writepage_io_hook) {
2398                         ret = tree->ops->writepage_io_hook(page, cur,
2399                                                 cur + iosize - 1);
2400                 } else {
2401                         ret = 0;
2402                 }
2403                 if (ret) {
2404                         SetPageError(page);
2405                 } else {
2406                         unsigned long max_nr = end_index + 1;
2407
2408                         set_range_writeback(tree, cur, cur + iosize - 1);
2409                         if (!PageWriteback(page)) {
2410                                 printk(KERN_ERR "btrfs warning page %lu not "
2411                                        "writeback, cur %llu end %llu\n",
2412                                        page->index, (unsigned long long)cur,
2413                                        (unsigned long long)end);
2414                         }
2415
2416                         ret = submit_extent_page(write_flags, tree, page,
2417                                                  sector, iosize, pg_offset,
2418                                                  bdev, &epd->bio, max_nr,
2419                                                  end_bio_extent_writepage,
2420                                                  0, 0, 0);
2421                         if (ret)
2422                                 SetPageError(page);
2423                 }
2424                 cur = cur + iosize;
2425                 pg_offset += iosize;
2426                 nr++;
2427         }
2428 done:
2429         if (nr == 0) {
2430                 /* make sure the mapping tag for page dirty gets cleared */
2431                 set_page_writeback(page);
2432                 end_page_writeback(page);
2433         }
2434         unlock_page(page);
2435
2436 done_unlocked:
2437
2438         /* drop our reference on any cached states */
2439         free_extent_state(cached_state);
2440         return 0;
2441 }
2442
2443 /**
2444  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
2445  * @mapping: address space structure to write
2446  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
2447  * @writepage: function called for each page
2448  * @data: data passed to writepage function
2449  *
2450  * If a page is already under I/O, write_cache_pages() skips it, even
2451  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
2452  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
2453  * and msync() need to guarantee that all the data which was dirty at the time
2454  * the call was made get new I/O started against them.  If wbc->sync_mode is
2455  * WB_SYNC_ALL then we were called for data integrity and we must wait for
2456  * existing IO to complete.
2457  */
2458 static int extent_write_cache_pages(struct extent_io_tree *tree,
2459                              struct address_space *mapping,
2460                              struct writeback_control *wbc,
2461                              writepage_t writepage, void *data,
2462                              void (*flush_fn)(void *))
2463 {
2464         int ret = 0;
2465         int done = 0;
2466         int nr_to_write_done = 0;
2467         struct pagevec pvec;
2468         int nr_pages;
2469         pgoff_t index;
2470         pgoff_t end;            /* Inclusive */
2471         int scanned = 0;
2472         int range_whole = 0;
2473
2474         pagevec_init(&pvec, 0);
2475         if (wbc->range_cyclic) {
2476                 index = mapping->writeback_index; /* Start from prev offset */
2477                 end = -1;
2478         } else {
2479                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2480                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
2481                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2482                         range_whole = 1;
2483                 scanned = 1;
2484         }
2485 retry:
2486         while (!done && !nr_to_write_done && (index <= end) &&
2487                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
2488                               PAGECACHE_TAG_DIRTY, min(end - index,
2489                                   (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
2490                 unsigned i;
2491
2492                 scanned = 1;
2493                 for (i = 0; i < nr_pages; i++) {
2494                         struct page *page = pvec.pages[i];
2495
2496                         /*
2497                          * At this point we hold neither mapping->tree_lock nor
2498                          * lock on the page itself: the page may be truncated or
2499                          * invalidated (changing page->mapping to NULL), or even
2500                          * swizzled back from swapper_space to tmpfs file
2501                          * mapping
2502                          */
2503                         if (tree->ops && tree->ops->write_cache_pages_lock_hook)
2504                                 tree->ops->write_cache_pages_lock_hook(page);
2505                         else
2506                                 lock_page(page);
2507
2508                         if (unlikely(page->mapping != mapping)) {
2509                                 unlock_page(page);
2510                                 continue;
2511                         }
2512
2513                         if (!wbc->range_cyclic && page->index > end) {
2514                                 done = 1;
2515                                 unlock_page(page);
2516                                 continue;
2517                         }
2518
2519                         if (wbc->sync_mode != WB_SYNC_NONE) {
2520                                 if (PageWriteback(page))
2521                                         flush_fn(data);
2522                                 wait_on_page_writeback(page);
2523                         }
2524
2525                         if (PageWriteback(page) ||
2526                             !clear_page_dirty_for_io(page)) {
2527                                 unlock_page(page);
2528                                 continue;
2529                         }
2530
2531                         ret = (*writepage)(page, wbc, data);
2532
2533                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
2534                                 unlock_page(page);
2535                                 ret = 0;
2536                         }
2537                         if (ret)
2538                                 done = 1;
2539
2540                         /*
2541                          * the filesystem may choose to bump up nr_to_write.
2542                          * We have to make sure to honor the new nr_to_write
2543                          * at any time
2544                          */
2545                         nr_to_write_done = wbc->nr_to_write <= 0;
2546                 }
2547                 pagevec_release(&pvec);
2548                 cond_resched();
2549         }
2550         if (!scanned && !done) {
2551                 /*
2552                  * We hit the last page and there is more work to be done: wrap
2553                  * back to the start of the file
2554                  */
2555                 scanned = 1;
2556                 index = 0;
2557                 goto retry;
2558         }
2559         return ret;
2560 }
2561
2562 static void flush_epd_write_bio(struct extent_page_data *epd)
2563 {
2564         if (epd->bio) {
2565                 if (epd->sync_io)
2566                         submit_one_bio(WRITE_SYNC, epd->bio, 0, 0);
2567                 else
2568                         submit_one_bio(WRITE, epd->bio, 0, 0);
2569                 epd->bio = NULL;
2570         }
2571 }
2572
2573 static noinline void flush_write_bio(void *data)
2574 {
2575         struct extent_page_data *epd = data;
2576         flush_epd_write_bio(epd);
2577 }
2578
2579 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
2580                           get_extent_t *get_extent,
2581                           struct writeback_control *wbc)
2582 {
2583         int ret;
2584         struct address_space *mapping = page->mapping;
2585         struct extent_page_data epd = {
2586                 .bio = NULL,
2587                 .tree = tree,
2588                 .get_extent = get_extent,
2589                 .extent_locked = 0,
2590                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
2591         };
2592         struct writeback_control wbc_writepages = {
2593                 .bdi            = wbc->bdi,
2594                 .sync_mode      = wbc->sync_mode,
2595                 .older_than_this = NULL,
2596                 .nr_to_write    = 64,
2597                 .range_start    = page_offset(page) + PAGE_CACHE_SIZE,
2598                 .range_end      = (loff_t)-1,
2599         };
2600
2601         ret = __extent_writepage(page, wbc, &epd);
2602
2603         extent_write_cache_pages(tree, mapping, &wbc_writepages,
2604                                  __extent_writepage, &epd, flush_write_bio);
2605         flush_epd_write_bio(&epd);
2606         return ret;
2607 }
2608
2609 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
2610                               u64 start, u64 end, get_extent_t *get_extent,
2611                               int mode)
2612 {
2613         int ret = 0;
2614         struct address_space *mapping = inode->i_mapping;
2615         struct page *page;
2616         unsigned long nr_pages = (end - start + PAGE_CACHE_SIZE) >>
2617                 PAGE_CACHE_SHIFT;
2618
2619         struct extent_page_data epd = {
2620                 .bio = NULL,
2621                 .tree = tree,
2622                 .get_extent = get_extent,
2623                 .extent_locked = 1,
2624                 .sync_io = mode == WB_SYNC_ALL,
2625         };
2626         struct writeback_control wbc_writepages = {
2627                 .bdi            = inode->i_mapping->backing_dev_info,
2628                 .sync_mode      = mode,
2629                 .older_than_this = NULL,
2630                 .nr_to_write    = nr_pages * 2,
2631                 .range_start    = start,
2632                 .range_end      = end + 1,
2633         };
2634
2635         while (start <= end) {
2636                 page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
2637                 if (clear_page_dirty_for_io(page))
2638                         ret = __extent_writepage(page, &wbc_writepages, &epd);
2639                 else {
2640                         if (tree->ops && tree->ops->writepage_end_io_hook)
2641                                 tree->ops->writepage_end_io_hook(page, start,
2642                                                  start + PAGE_CACHE_SIZE - 1,
2643                                                  NULL, 1);
2644                         unlock_page(page);
2645                 }
2646                 page_cache_release(page);
2647                 start += PAGE_CACHE_SIZE;
2648         }
2649
2650         flush_epd_write_bio(&epd);
2651         return ret;
2652 }
2653
2654 int extent_writepages(struct extent_io_tree *tree,
2655                       struct address_space *mapping,
2656                       get_extent_t *get_extent,
2657                       struct writeback_control *wbc)
2658 {
2659         int ret = 0;
2660         struct extent_page_data epd = {
2661                 .bio = NULL,
2662                 .tree = tree,
2663                 .get_extent = get_extent,
2664                 .extent_locked = 0,
2665                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
2666         };
2667
2668         ret = extent_write_cache_pages(tree, mapping, wbc,
2669                                        __extent_writepage, &epd,
2670                                        flush_write_bio);
2671         flush_epd_write_bio(&epd);
2672         return ret;
2673 }
2674
2675 int extent_readpages(struct extent_io_tree *tree,
2676                      struct address_space *mapping,
2677                      struct list_head *pages, unsigned nr_pages,
2678                      get_extent_t get_extent)
2679 {
2680         struct bio *bio = NULL;
2681         unsigned page_idx;
2682         struct pagevec pvec;
2683         unsigned long bio_flags = 0;
2684
2685         pagevec_init(&pvec, 0);
2686         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
2687                 struct page *page = list_entry(pages->prev, struct page, lru);
2688
2689                 prefetchw(&page->flags);
2690                 list_del(&page->lru);
2691                 /*
2692                  * what we want to do here is call add_to_page_cache_lru,
2693                  * but that isn't exported, so we reproduce it here
2694                  */
2695                 if (!add_to_page_cache(page, mapping,
2696                                         page->index, GFP_KERNEL)) {
2697
2698                         /* open coding of lru_cache_add, also not exported */
2699                         page_cache_get(page);
2700                         if (!pagevec_add(&pvec, page))
2701                                 __pagevec_lru_add_file(&pvec);
2702                         __extent_read_full_page(tree, page, get_extent,
2703                                                 &bio, 0, &bio_flags);
2704                 }
2705                 page_cache_release(page);
2706         }
2707         if (pagevec_count(&pvec))
2708                 __pagevec_lru_add_file(&pvec);
2709         BUG_ON(!list_empty(pages));
2710         if (bio)
2711                 submit_one_bio(READ, bio, 0, bio_flags);
2712         return 0;
2713 }
2714
2715 /*
2716  * basic invalidatepage code, this waits on any locked or writeback
2717  * ranges corresponding to the page, and then deletes any extent state
2718  * records from the tree
2719  */
2720 int extent_invalidatepage(struct extent_io_tree *tree,
2721                           struct page *page, unsigned long offset)
2722 {
2723         struct extent_state *cached_state = NULL;
2724         u64 start = ((u64)page->index << PAGE_CACHE_SHIFT);
2725         u64 end = start + PAGE_CACHE_SIZE - 1;
2726         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
2727
2728         start += (offset + blocksize - 1) & ~(blocksize - 1);
2729         if (start > end)
2730                 return 0;
2731
2732         lock_extent_bits(tree, start, end, 0, &cached_state, GFP_NOFS);
2733         wait_on_page_writeback(page);
2734         clear_extent_bit(tree, start, end,
2735                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
2736                          EXTENT_DO_ACCOUNTING,
2737                          1, 1, &cached_state, GFP_NOFS);
2738         return 0;
2739 }
2740
2741 /*
2742  * simple commit_write call, set_range_dirty is used to mark both
2743  * the pages and the extent records as dirty
2744  */
2745 int extent_commit_write(struct extent_io_tree *tree,
2746                         struct inode *inode, struct page *page,
2747                         unsigned from, unsigned to)
2748 {
2749         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
2750
2751         set_page_extent_mapped(page);
2752         set_page_dirty(page);
2753
2754         if (pos > inode->i_size) {
2755                 i_size_write(inode, pos);
2756                 mark_inode_dirty(inode);
2757         }
2758         return 0;
2759 }
2760
2761 int extent_prepare_write(struct extent_io_tree *tree,
2762                          struct inode *inode, struct page *page,
2763                          unsigned from, unsigned to, get_extent_t *get_extent)
2764 {
2765         u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2766         u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
2767         u64 block_start;
2768         u64 orig_block_start;
2769         u64 block_end;
2770         u64 cur_end;
2771         struct extent_map *em;
2772         unsigned blocksize = 1 << inode->i_blkbits;
2773         size_t page_offset = 0;
2774         size_t block_off_start;
2775         size_t block_off_end;
2776         int err = 0;
2777         int iocount = 0;
2778         int ret = 0;
2779         int isnew;
2780
2781         set_page_extent_mapped(page);
2782
2783         block_start = (page_start + from) & ~((u64)blocksize - 1);
2784         block_end = (page_start + to - 1) | (blocksize - 1);
2785         orig_block_start = block_start;
2786
2787         lock_extent(tree, page_start, page_end, GFP_NOFS);
2788         while (block_start <= block_end) {
2789                 em = get_extent(inode, page, page_offset, block_start,
2790                                 block_end - block_start + 1, 1);
2791                 if (IS_ERR(em) || !em)
2792                         goto err;
2793
2794                 cur_end = min(block_end, extent_map_end(em) - 1);
2795                 block_off_start = block_start & (PAGE_CACHE_SIZE - 1);
2796                 block_off_end = block_off_start + blocksize;
2797                 isnew = clear_extent_new(tree, block_start, cur_end, GFP_NOFS);
2798
2799                 if (!PageUptodate(page) && isnew &&
2800                     (block_off_end > to || block_off_start < from)) {
2801                         void *kaddr;
2802
2803                         kaddr = kmap_atomic(page, KM_USER0);
2804                         if (block_off_end > to)
2805                                 memset(kaddr + to, 0, block_off_end - to);
2806                         if (block_off_start < from)
2807                                 memset(kaddr + block_off_start, 0,
2808                                        from - block_off_start);
2809                         flush_dcache_page(page);
2810                         kunmap_atomic(kaddr, KM_USER0);
2811                 }
2812                 if ((em->block_start != EXTENT_MAP_HOLE &&
2813                      em->block_start != EXTENT_MAP_INLINE) &&
2814                     !isnew && !PageUptodate(page) &&
2815                     (block_off_end > to || block_off_start < from) &&
2816                     !test_range_bit(tree, block_start, cur_end,
2817                                     EXTENT_UPTODATE, 1, NULL)) {
2818                         u64 sector;
2819                         u64 extent_offset = block_start - em->start;
2820                         size_t iosize;
2821                         sector = (em->block_start + extent_offset) >> 9;
2822                         iosize = (cur_end - block_start + blocksize) &
2823                                 ~((u64)blocksize - 1);
2824                         /*
2825                          * we've already got the extent locked, but we
2826                          * need to split the state such that our end_bio
2827                          * handler can clear the lock.
2828                          */
2829                         set_extent_bit(tree, block_start,
2830                                        block_start + iosize - 1,
2831                                        EXTENT_LOCKED, 0, NULL, NULL, GFP_NOFS);
2832                         ret = submit_extent_page(READ, tree, page,
2833                                          sector, iosize, page_offset, em->bdev,
2834                                          NULL, 1,
2835                                          end_bio_extent_preparewrite, 0,
2836                                          0, 0);
2837                         iocount++;
2838                         block_start = block_start + iosize;
2839                 } else {
2840                         set_extent_uptodate(tree, block_start, cur_end,
2841                                             GFP_NOFS);
2842                         unlock_extent(tree, block_start, cur_end, GFP_NOFS);
2843                         block_start = cur_end + 1;
2844                 }
2845                 page_offset = block_start & (PAGE_CACHE_SIZE - 1);
2846                 free_extent_map(em);
2847         }
2848         if (iocount) {
2849                 wait_extent_bit(tree, orig_block_start,
2850                                 block_end, EXTENT_LOCKED);
2851         }
2852         check_page_uptodate(tree, page);
2853 err:
2854         /* FIXME, zero out newly allocated blocks on error */
2855         return err;
2856 }
2857
2858 /*
2859  * a helper for releasepage, this tests for areas of the page that
2860  * are locked or under IO and drops the related state bits if it is safe
2861  * to drop the page.
2862  */
2863 int try_release_extent_state(struct extent_map_tree *map,
2864                              struct extent_io_tree *tree, struct page *page,
2865                              gfp_t mask)
2866 {
2867         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2868         u64 end = start + PAGE_CACHE_SIZE - 1;
2869         int ret = 1;
2870
2871         if (test_range_bit(tree, start, end,
2872                            EXTENT_IOBITS, 0, NULL))
2873                 ret = 0;
2874         else {
2875                 if ((mask & GFP_NOFS) == GFP_NOFS)
2876                         mask = GFP_NOFS;
2877                 /*
2878                  * at this point we can safely clear everything except the
2879                  * locked bit and the nodatasum bit
2880                  */
2881                 clear_extent_bit(tree, start, end,
2882                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
2883                                  0, 0, NULL, mask);
2884         }
2885         return ret;
2886 }
2887
2888 /*
2889  * a helper for releasepage.  As long as there are no locked extents
2890  * in the range corresponding to the page, both state records and extent
2891  * map records are removed
2892  */
2893 int try_release_extent_mapping(struct extent_map_tree *map,
2894                                struct extent_io_tree *tree, struct page *page,
2895                                gfp_t mask)
2896 {
2897         struct extent_map *em;
2898         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
2899         u64 end = start + PAGE_CACHE_SIZE - 1;
2900
2901         if ((mask & __GFP_WAIT) &&
2902             page->mapping->host->i_size > 16 * 1024 * 1024) {
2903                 u64 len;
2904                 while (start <= end) {
2905                         len = end - start + 1;
2906                         write_lock(&map->lock);
2907                         em = lookup_extent_mapping(map, start, len);
2908                         if (!em || IS_ERR(em)) {
2909                                 write_unlock(&map->lock);
2910                                 break;
2911                         }
2912                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
2913                             em->start != start) {
2914                                 write_unlock(&map->lock);
2915                                 free_extent_map(em);
2916                                 break;
2917                         }
2918                         if (!test_range_bit(tree, em->start,
2919                                             extent_map_end(em) - 1,
2920                                             EXTENT_LOCKED | EXTENT_WRITEBACK,
2921                                             0, NULL)) {
2922                                 remove_extent_mapping(map, em);
2923                                 /* once for the rb tree */
2924                                 free_extent_map(em);
2925                         }
2926                         start = extent_map_end(em);
2927                         write_unlock(&map->lock);
2928
2929                         /* once for us */
2930                         free_extent_map(em);
2931                 }
2932         }
2933         return try_release_extent_state(map, tree, page, mask);
2934 }
2935
2936 sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
2937                 get_extent_t *get_extent)
2938 {
2939         struct inode *inode = mapping->host;
2940         struct extent_state *cached_state = NULL;
2941         u64 start = iblock << inode->i_blkbits;
2942         sector_t sector = 0;
2943         size_t blksize = (1 << inode->i_blkbits);
2944         struct extent_map *em;
2945
2946         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + blksize - 1,
2947                          0, &cached_state, GFP_NOFS);
2948         em = get_extent(inode, NULL, 0, start, blksize, 0);
2949         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start,
2950                              start + blksize - 1, &cached_state, GFP_NOFS);
2951         if (!em || IS_ERR(em))
2952                 return 0;
2953
2954         if (em->block_start > EXTENT_MAP_LAST_BYTE)
2955                 goto out;
2956
2957         sector = (em->block_start + start - em->start) >> inode->i_blkbits;
2958 out:
2959         free_extent_map(em);
2960         return sector;
2961 }
2962
2963 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
2964                 __u64 start, __u64 len, get_extent_t *get_extent)
2965 {
2966         int ret;
2967         u64 off = start;
2968         u64 max = start + len;
2969         u32 flags = 0;
2970         u64 disko = 0;
2971         struct extent_map *em = NULL;
2972         struct extent_state *cached_state = NULL;
2973         int end = 0;
2974         u64 em_start = 0, em_len = 0;
2975         unsigned long emflags;
2976         ret = 0;
2977
2978         if (len == 0)
2979                 return -EINVAL;
2980
2981         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len, 0,
2982                          &cached_state, GFP_NOFS);
2983         em = get_extent(inode, NULL, 0, off, max - off, 0);
2984         if (!em)
2985                 goto out;
2986         if (IS_ERR(em)) {
2987                 ret = PTR_ERR(em);
2988                 goto out;
2989         }
2990         while (!end) {
2991                 off = em->start + em->len;
2992                 if (off >= max)
2993                         end = 1;
2994
2995                 em_start = em->start;
2996                 em_len = em->len;
2997
2998                 disko = 0;
2999                 flags = 0;
3000
3001                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
3002                         end = 1;
3003                         flags |= FIEMAP_EXTENT_LAST;
3004                 } else if (em->block_start == EXTENT_MAP_HOLE) {
3005                         flags |= FIEMAP_EXTENT_UNWRITTEN;
3006                 } else if (em->block_start == EXTENT_MAP_INLINE) {
3007                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
3008                                   FIEMAP_EXTENT_NOT_ALIGNED);
3009                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
3010                         flags |= (FIEMAP_EXTENT_DELALLOC |
3011                                   FIEMAP_EXTENT_UNKNOWN);
3012                 } else {
3013                         disko = em->block_start;
3014                 }
3015                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
3016                         flags |= FIEMAP_EXTENT_ENCODED;
3017
3018                 emflags = em->flags;
3019                 free_extent_map(em);
3020                 em = NULL;
3021
3022                 if (!end) {
3023                         em = get_extent(inode, NULL, 0, off, max - off, 0);
3024                         if (!em)
3025                                 goto out;
3026                         if (IS_ERR(em)) {
3027                                 ret = PTR_ERR(em);
3028                                 goto out;
3029                         }
3030                         emflags = em->flags;
3031                 }
3032                 if (test_bit(EXTENT_FLAG_VACANCY, &emflags)) {
3033                         flags |= FIEMAP_EXTENT_LAST;
3034                         end = 1;
3035                 }
3036
3037                 ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
3038                                         em_len, flags);
3039                 if (ret)
3040                         goto out_free;
3041         }
3042 out_free:
3043         free_extent_map(em);
3044 out:
3045         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len,
3046                              &cached_state, GFP_NOFS);
3047         return ret;
3048 }
3049
3050 static inline struct page *extent_buffer_page(struct extent_buffer *eb,
3051                                               unsigned long i)
3052 {
3053         struct page *p;
3054         struct address_space *mapping;
3055
3056         if (i == 0)
3057                 return eb->first_page;
3058         i += eb->start >> PAGE_CACHE_SHIFT;
3059         mapping = eb->first_page->mapping;
3060         if (!mapping)
3061                 return NULL;
3062
3063         /*
3064          * extent_buffer_page is only called after pinning the page
3065          * by increasing the reference count.  So we know the page must
3066          * be in the radix tree.
3067          */
3068         rcu_read_lock();
3069         p = radix_tree_lookup(&mapping->page_tree, i);
3070         rcu_read_unlock();
3071
3072         return p;
3073 }
3074
3075 static inline unsigned long num_extent_pages(u64 start, u64 len)
3076 {
3077         return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
3078                 (start >> PAGE_CACHE_SHIFT);
3079 }
3080
3081 static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
3082                                                    u64 start,
3083                                                    unsigned long len,
3084                                                    gfp_t mask)
3085 {
3086         struct extent_buffer *eb = NULL;
3087 #if LEAK_DEBUG
3088         unsigned long flags;
3089 #endif
3090
3091         eb = kmem_cache_zalloc(extent_buffer_cache, mask);
3092         eb->start = start;
3093         eb->len = len;
3094         spin_lock_init(&eb->lock);
3095         init_waitqueue_head(&eb->lock_wq);
3096
3097 #if LEAK_DEBUG
3098         spin_lock_irqsave(&leak_lock, flags);
3099         list_add(&eb->leak_list, &buffers);
3100         spin_unlock_irqrestore(&leak_lock, flags);
3101 #endif
3102         atomic_set(&eb->refs, 1);
3103
3104         return eb;
3105 }
3106
3107 static void __free_extent_buffer(struct extent_buffer *eb)
3108 {
3109 #if LEAK_DEBUG
3110         unsigned long flags;
3111         spin_lock_irqsave(&leak_lock, flags);
3112         list_del(&eb->leak_list);
3113         spin_unlock_irqrestore(&leak_lock, flags);
3114 #endif
3115         kmem_cache_free(extent_buffer_cache, eb);
3116 }
3117
3118 struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
3119                                           u64 start, unsigned long len,
3120                                           struct page *page0,
3121                                           gfp_t mask)
3122 {
3123         unsigned long num_pages = num_extent_pages(start, len);
3124         unsigned long i;
3125         unsigned long index = start >> PAGE_CACHE_SHIFT;
3126         struct extent_buffer *eb;
3127         struct extent_buffer *exists = NULL;
3128         struct page *p;
3129         struct address_space *mapping = tree->mapping;
3130         int uptodate = 1;
3131
3132         spin_lock(&tree->buffer_lock);
3133         eb = buffer_search(tree, start);
3134         if (eb) {
3135                 atomic_inc(&eb->refs);
3136                 spin_unlock(&tree->buffer_lock);
3137                 mark_page_accessed(eb->first_page);
3138                 return eb;
3139         }
3140         spin_unlock(&tree->buffer_lock);
3141
3142         eb = __alloc_extent_buffer(tree, start, len, mask);
3143         if (!eb)
3144                 return NULL;
3145
3146         if (page0) {
3147                 eb->first_page = page0;
3148                 i = 1;
3149                 index++;
3150                 page_cache_get(page0);
3151                 mark_page_accessed(page0);
3152                 set_page_extent_mapped(page0);
3153                 set_page_extent_head(page0, len);
3154                 uptodate = PageUptodate(page0);
3155         } else {
3156                 i = 0;
3157         }
3158         for (; i < num_pages; i++, index++) {
3159                 p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
3160                 if (!p) {
3161                         WARN_ON(1);
3162                         goto free_eb;
3163                 }
3164                 set_page_extent_mapped(p);
3165                 mark_page_accessed(p);
3166                 if (i == 0) {
3167                         eb->first_page = p;
3168                         set_page_extent_head(p, len);
3169                 } else {
3170                         set_page_private(p, EXTENT_PAGE_PRIVATE);
3171                 }
3172                 if (!PageUptodate(p))
3173                         uptodate = 0;
3174                 unlock_page(p);
3175         }
3176         if (uptodate)
3177                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3178
3179         spin_lock(&tree->buffer_lock);
3180         exists = buffer_tree_insert(tree, start, &eb->rb_node);
3181         if (exists) {
3182                 /* add one reference for the caller */
3183                 atomic_inc(&exists->refs);
3184                 spin_unlock(&tree->buffer_lock);
3185                 goto free_eb;
3186         }
3187         /* add one reference for the tree */
3188         atomic_inc(&eb->refs);
3189         spin_unlock(&tree->buffer_lock);
3190         return eb;
3191
3192 free_eb:
3193         if (!atomic_dec_and_test(&eb->refs))
3194                 return exists;
3195         for (index = 1; index < i; index++)
3196                 page_cache_release(extent_buffer_page(eb, index));
3197         page_cache_release(extent_buffer_page(eb, 0));
3198         __free_extent_buffer(eb);
3199         return exists;
3200 }
3201
3202 struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
3203                                          u64 start, unsigned long len,
3204                                           gfp_t mask)
3205 {
3206         struct extent_buffer *eb;
3207
3208         spin_lock(&tree->buffer_lock);
3209         eb = buffer_search(tree, start);
3210         if (eb)
3211                 atomic_inc(&eb->refs);
3212         spin_unlock(&tree->buffer_lock);
3213
3214         if (eb)
3215                 mark_page_accessed(eb->first_page);
3216
3217         return eb;
3218 }
3219
3220 void free_extent_buffer(struct extent_buffer *eb)
3221 {
3222         if (!eb)
3223                 return;
3224
3225         if (!atomic_dec_and_test(&eb->refs))
3226                 return;
3227
3228         WARN_ON(1);
3229 }
3230
3231 int clear_extent_buffer_dirty(struct extent_io_tree *tree,
3232                               struct extent_buffer *eb)
3233 {
3234         unsigned long i;
3235         unsigned long num_pages;
3236         struct page *page;
3237
3238         num_pages = num_extent_pages(eb->start, eb->len);
3239
3240         for (i = 0; i < num_pages; i++) {
3241                 page = extent_buffer_page(eb, i);
3242                 if (!PageDirty(page))
3243                         continue;
3244
3245                 lock_page(page);
3246                 if (i == 0)
3247                         set_page_extent_head(page, eb->len);
3248                 else
3249                         set_page_private(page, EXTENT_PAGE_PRIVATE);
3250
3251                 clear_page_dirty_for_io(page);
3252                 spin_lock_irq(&page->mapping->tree_lock);
3253                 if (!PageDirty(page)) {
3254                         radix_tree_tag_clear(&page->mapping->page_tree,
3255                                                 page_index(page),
3256                                                 PAGECACHE_TAG_DIRTY);
3257                 }
3258                 spin_unlock_irq(&page->mapping->tree_lock);
3259                 unlock_page(page);
3260         }
3261         return 0;
3262 }
3263
3264 int wait_on_extent_buffer_writeback(struct extent_io_tree *tree,
3265                                     struct extent_buffer *eb)
3266 {
3267         return wait_on_extent_writeback(tree, eb->start,
3268                                         eb->start + eb->len - 1);
3269 }
3270
3271 int set_extent_buffer_dirty(struct extent_io_tree *tree,
3272                              struct extent_buffer *eb)
3273 {
3274         unsigned long i;
3275         unsigned long num_pages;
3276         int was_dirty = 0;
3277
3278         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
3279         num_pages = num_extent_pages(eb->start, eb->len);
3280         for (i = 0; i < num_pages; i++)
3281                 __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
3282         return was_dirty;
3283 }
3284
3285 int clear_extent_buffer_uptodate(struct extent_io_tree *tree,
3286                                 struct extent_buffer *eb,
3287                                 struct extent_state **cached_state)
3288 {
3289         unsigned long i;
3290         struct page *page;
3291         unsigned long num_pages;
3292
3293         num_pages = num_extent_pages(eb->start, eb->len);
3294         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3295
3296         clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
3297                               cached_state, GFP_NOFS);
3298         for (i = 0; i < num_pages; i++) {
3299                 page = extent_buffer_page(eb, i);
3300                 if (page)
3301                         ClearPageUptodate(page);
3302         }
3303         return 0;
3304 }
3305
3306 int set_extent_buffer_uptodate(struct extent_io_tree *tree,
3307                                 struct extent_buffer *eb)
3308 {
3309         unsigned long i;
3310         struct page *page;
3311         unsigned long num_pages;
3312
3313         num_pages = num_extent_pages(eb->start, eb->len);
3314
3315         set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
3316                             GFP_NOFS);
3317         for (i = 0; i < num_pages; i++) {
3318                 page = extent_buffer_page(eb, i);
3319                 if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
3320                     ((i == num_pages - 1) &&
3321                      ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
3322                         check_page_uptodate(tree, page);
3323                         continue;
3324                 }
3325                 SetPageUptodate(page);
3326         }
3327         return 0;
3328 }
3329
3330 int extent_range_uptodate(struct extent_io_tree *tree,
3331                           u64 start, u64 end)
3332 {
3333         struct page *page;
3334         int ret;
3335         int pg_uptodate = 1;
3336         int uptodate;
3337         unsigned long index;
3338
3339         ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL);
3340         if (ret)
3341                 return 1;
3342         while (start <= end) {
3343                 index = start >> PAGE_CACHE_SHIFT;
3344                 page = find_get_page(tree->mapping, index);
3345                 uptodate = PageUptodate(page);
3346                 page_cache_release(page);
3347                 if (!uptodate) {
3348                         pg_uptodate = 0;
3349                         break;
3350                 }
3351                 start += PAGE_CACHE_SIZE;
3352         }
3353         return pg_uptodate;
3354 }
3355
3356 int extent_buffer_uptodate(struct extent_io_tree *tree,
3357                            struct extent_buffer *eb,
3358                            struct extent_state *cached_state)
3359 {
3360         int ret = 0;
3361         unsigned long num_pages;
3362         unsigned long i;
3363         struct page *page;
3364         int pg_uptodate = 1;
3365
3366         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
3367                 return 1;
3368
3369         ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1,
3370                            EXTENT_UPTODATE, 1, cached_state);
3371         if (ret)
3372                 return ret;
3373
3374         num_pages = num_extent_pages(eb->start, eb->len);
3375         for (i = 0; i < num_pages; i++) {
3376                 page = extent_buffer_page(eb, i);
3377                 if (!PageUptodate(page)) {
3378                         pg_uptodate = 0;
3379                         break;
3380                 }
3381         }
3382         return pg_uptodate;
3383 }
3384
3385 int read_extent_buffer_pages(struct extent_io_tree *tree,
3386                              struct extent_buffer *eb,
3387                              u64 start, int wait,
3388                              get_extent_t *get_extent, int mirror_num)
3389 {
3390         unsigned long i;
3391         unsigned long start_i;
3392         struct page *page;
3393         int err;
3394         int ret = 0;
3395         int locked_pages = 0;
3396         int all_uptodate = 1;
3397         int inc_all_pages = 0;
3398         unsigned long num_pages;
3399         struct bio *bio = NULL;
3400         unsigned long bio_flags = 0;
3401
3402         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
3403                 return 0;
3404
3405         if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,
3406                            EXTENT_UPTODATE, 1, NULL)) {
3407                 return 0;
3408         }
3409
3410         if (start) {
3411                 WARN_ON(start < eb->start);
3412                 start_i = (start >> PAGE_CACHE_SHIFT) -
3413                         (eb->start >> PAGE_CACHE_SHIFT);
3414         } else {
3415                 start_i = 0;
3416         }
3417
3418         num_pages = num_extent_pages(eb->start, eb->len);
3419         for (i = start_i; i < num_pages; i++) {
3420                 page = extent_buffer_page(eb, i);
3421                 if (!wait) {
3422                         if (!trylock_page(page))
3423                                 goto unlock_exit;
3424                 } else {
3425                         lock_page(page);
3426                 }
3427                 locked_pages++;
3428                 if (!PageUptodate(page))
3429                         all_uptodate = 0;
3430         }
3431         if (all_uptodate) {
3432                 if (start_i == 0)
3433                         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3434                 goto unlock_exit;
3435         }
3436
3437         for (i = start_i; i < num_pages; i++) {
3438                 page = extent_buffer_page(eb, i);
3439                 if (inc_all_pages)
3440                         page_cache_get(page);
3441                 if (!PageUptodate(page)) {
3442                         if (start_i == 0)
3443                                 inc_all_pages = 1;
3444                         ClearPageError(page);
3445                         err = __extent_read_full_page(tree, page,
3446                                                       get_extent, &bio,
3447                                                       mirror_num, &bio_flags);
3448                         if (err)
3449                                 ret = err;
3450                 } else {
3451                         unlock_page(page);
3452                 }
3453         }
3454
3455         if (bio)
3456                 submit_one_bio(READ, bio, mirror_num, bio_flags);
3457
3458         if (ret || !wait)
3459                 return ret;
3460
3461         for (i = start_i; i < num_pages; i++) {
3462                 page = extent_buffer_page(eb, i);
3463                 wait_on_page_locked(page);
3464                 if (!PageUptodate(page))
3465                         ret = -EIO;
3466         }
3467
3468         if (!ret)
3469                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3470         return ret;
3471
3472 unlock_exit:
3473         i = start_i;
3474         while (locked_pages > 0) {
3475                 page = extent_buffer_page(eb, i);
3476                 i++;
3477                 unlock_page(page);
3478                 locked_pages--;
3479         }
3480         return ret;
3481 }
3482
3483 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
3484                         unsigned long start,
3485                         unsigned long len)
3486 {
3487         size_t cur;
3488         size_t offset;
3489         struct page *page;
3490         char *kaddr;
3491         char *dst = (char *)dstv;
3492         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3493         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3494
3495         WARN_ON(start > eb->len);
3496         WARN_ON(start + len > eb->start + eb->len);
3497
3498         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3499
3500         while (len > 0) {
3501                 page = extent_buffer_page(eb, i);
3502
3503                 cur = min(len, (PAGE_CACHE_SIZE - offset));
3504                 kaddr = kmap_atomic(page, KM_USER1);
3505                 memcpy(dst, kaddr + offset, cur);
3506                 kunmap_atomic(kaddr, KM_USER1);
3507
3508                 dst += cur;
3509                 len -= cur;
3510                 offset = 0;
3511                 i++;
3512         }
3513 }
3514
3515 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
3516                                unsigned long min_len, char **token, char **map,
3517                                unsigned long *map_start,
3518                                unsigned long *map_len, int km)
3519 {
3520         size_t offset = start & (PAGE_CACHE_SIZE - 1);
3521         char *kaddr;
3522         struct page *p;
3523         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3524         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3525         unsigned long end_i = (start_offset + start + min_len - 1) >>
3526                 PAGE_CACHE_SHIFT;
3527
3528         if (i != end_i)
3529                 return -EINVAL;
3530
3531         if (i == 0) {
3532                 offset = start_offset;
3533                 *map_start = 0;
3534         } else {
3535                 offset = 0;
3536                 *map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
3537         }
3538
3539         if (start + min_len > eb->len) {
3540                 printk(KERN_ERR "btrfs bad mapping eb start %llu len %lu, "
3541                        "wanted %lu %lu\n", (unsigned long long)eb->start,
3542                        eb->len, start, min_len);
3543                 WARN_ON(1);
3544         }
3545
3546         p = extent_buffer_page(eb, i);
3547         kaddr = kmap_atomic(p, km);
3548         *token = kaddr;
3549         *map = kaddr + offset;
3550         *map_len = PAGE_CACHE_SIZE - offset;
3551         return 0;
3552 }
3553
3554 int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
3555                       unsigned long min_len,
3556                       char **token, char **map,
3557                       unsigned long *map_start,
3558                       unsigned long *map_len, int km)
3559 {
3560         int err;
3561         int save = 0;
3562         if (eb->map_token) {
3563                 unmap_extent_buffer(eb, eb->map_token, km);
3564                 eb->map_token = NULL;
3565                 save = 1;
3566         }
3567         err = map_private_extent_buffer(eb, start, min_len, token, map,
3568                                        map_start, map_len, km);
3569         if (!err && save) {
3570                 eb->map_token = *token;
3571                 eb->kaddr = *map;
3572                 eb->map_start = *map_start;
3573                 eb->map_len = *map_len;
3574         }
3575         return err;
3576 }
3577
3578 void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km)
3579 {
3580         kunmap_atomic(token, km);
3581 }
3582
3583 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
3584                           unsigned long start,
3585                           unsigned long len)
3586 {
3587         size_t cur;
3588         size_t offset;
3589         struct page *page;
3590         char *kaddr;
3591         char *ptr = (char *)ptrv;
3592         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3593         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3594         int ret = 0;
3595
3596         WARN_ON(start > eb->len);
3597         WARN_ON(start + len > eb->start + eb->len);
3598
3599         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3600
3601         while (len > 0) {
3602                 page = extent_buffer_page(eb, i);
3603
3604                 cur = min(len, (PAGE_CACHE_SIZE - offset));
3605
3606                 kaddr = kmap_atomic(page, KM_USER0);
3607                 ret = memcmp(ptr, kaddr + offset, cur);
3608                 kunmap_atomic(kaddr, KM_USER0);
3609                 if (ret)
3610                         break;
3611
3612                 ptr += cur;
3613                 len -= cur;
3614                 offset = 0;
3615                 i++;
3616         }
3617         return ret;
3618 }
3619
3620 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
3621                          unsigned long start, unsigned long len)
3622 {
3623         size_t cur;
3624         size_t offset;
3625         struct page *page;
3626         char *kaddr;
3627         char *src = (char *)srcv;
3628         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3629         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3630
3631         WARN_ON(start > eb->len);
3632         WARN_ON(start + len > eb->start + eb->len);
3633
3634         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3635
3636         while (len > 0) {
3637                 page = extent_buffer_page(eb, i);
3638                 WARN_ON(!PageUptodate(page));
3639
3640                 cur = min(len, PAGE_CACHE_SIZE - offset);
3641                 kaddr = kmap_atomic(page, KM_USER1);
3642                 memcpy(kaddr + offset, src, cur);
3643                 kunmap_atomic(kaddr, KM_USER1);
3644
3645                 src += cur;
3646                 len -= cur;
3647                 offset = 0;
3648                 i++;
3649         }
3650 }
3651
3652 void memset_extent_buffer(struct extent_buffer *eb, char c,
3653                           unsigned long start, unsigned long len)
3654 {
3655         size_t cur;
3656         size_t offset;
3657         struct page *page;
3658         char *kaddr;
3659         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
3660         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
3661
3662         WARN_ON(start > eb->len);
3663         WARN_ON(start + len > eb->start + eb->len);
3664
3665         offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
3666
3667         while (len > 0) {
3668                 page = extent_buffer_page(eb, i);
3669                 WARN_ON(!PageUptodate(page));
3670
3671                 cur = min(len, PAGE_CACHE_SIZE - offset);
3672                 kaddr = kmap_atomic(page, KM_USER0);
3673                 memset(kaddr + offset, c, cur);
3674                 kunmap_atomic(kaddr, KM_USER0);
3675
3676                 len -= cur;
3677                 offset = 0;
3678                 i++;
3679         }
3680 }
3681
3682 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
3683                         unsigned long dst_offset, unsigned long src_offset,
3684                         unsigned long len)
3685 {
3686         u64 dst_len = dst->len;
3687         size_t cur;
3688         size_t offset;
3689         struct page *page;
3690         char *kaddr;
3691         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3692         unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
3693
3694         WARN_ON(src->len != dst_len);
3695
3696         offset = (start_offset + dst_offset) &
3697                 ((unsigned long)PAGE_CACHE_SIZE - 1);
3698
3699         while (len > 0) {
3700                 page = extent_buffer_page(dst, i);
3701                 WARN_ON(!PageUptodate(page));
3702
3703                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
3704
3705                 kaddr = kmap_atomic(page, KM_USER0);
3706                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
3707                 kunmap_atomic(kaddr, KM_USER0);
3708
3709                 src_offset += cur;
3710                 len -= cur;
3711                 offset = 0;
3712                 i++;
3713         }
3714 }
3715
3716 static void move_pages(struct page *dst_page, struct page *src_page,
3717                        unsigned long dst_off, unsigned long src_off,
3718                        unsigned long len)
3719 {
3720         char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
3721         if (dst_page == src_page) {
3722                 memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len);
3723         } else {
3724                 char *src_kaddr = kmap_atomic(src_page, KM_USER1);
3725                 char *p = dst_kaddr + dst_off + len;
3726                 char *s = src_kaddr + src_off + len;
3727
3728                 while (len--)
3729                         *--p = *--s;
3730
3731                 kunmap_atomic(src_kaddr, KM_USER1);
3732         }
3733         kunmap_atomic(dst_kaddr, KM_USER0);
3734 }
3735
3736 static void copy_pages(struct page *dst_page, struct page *src_page,
3737                        unsigned long dst_off, unsigned long src_off,
3738                        unsigned long len)
3739 {
3740         char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
3741         char *src_kaddr;
3742
3743         if (dst_page != src_page)
3744                 src_kaddr = kmap_atomic(src_page, KM_USER1);
3745         else
3746                 src_kaddr = dst_kaddr;
3747
3748         memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
3749         kunmap_atomic(dst_kaddr, KM_USER0);
3750         if (dst_page != src_page)
3751                 kunmap_atomic(src_kaddr, KM_USER1);
3752 }
3753
3754 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
3755                            unsigned long src_offset, unsigned long len)
3756 {
3757         size_t cur;
3758         size_t dst_off_in_page;
3759         size_t src_off_in_page;
3760         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3761         unsigned long dst_i;
3762         unsigned long src_i;
3763
3764         if (src_offset + len > dst->len) {
3765                 printk(KERN_ERR "btrfs memmove bogus src_offset %lu move "
3766                        "len %lu dst len %lu\n", src_offset, len, dst->len);
3767                 BUG_ON(1);
3768         }
3769         if (dst_offset + len > dst->len) {
3770                 printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move "
3771                        "len %lu dst len %lu\n", dst_offset, len, dst->len);
3772                 BUG_ON(1);
3773         }
3774
3775         while (len > 0) {
3776                 dst_off_in_page = (start_offset + dst_offset) &
3777                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3778                 src_off_in_page = (start_offset + src_offset) &
3779                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3780
3781                 dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
3782                 src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
3783
3784                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
3785                                                src_off_in_page));
3786                 cur = min_t(unsigned long, cur,
3787                         (unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
3788
3789                 copy_pages(extent_buffer_page(dst, dst_i),
3790                            extent_buffer_page(dst, src_i),
3791                            dst_off_in_page, src_off_in_page, cur);
3792
3793                 src_offset += cur;
3794                 dst_offset += cur;
3795                 len -= cur;
3796         }
3797 }
3798
3799 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
3800                            unsigned long src_offset, unsigned long len)
3801 {
3802         size_t cur;
3803         size_t dst_off_in_page;
3804         size_t src_off_in_page;
3805         unsigned long dst_end = dst_offset + len - 1;
3806         unsigned long src_end = src_offset + len - 1;
3807         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
3808         unsigned long dst_i;
3809         unsigned long src_i;
3810
3811         if (src_offset + len > dst->len) {
3812                 printk(KERN_ERR "btrfs memmove bogus src_offset %lu move "
3813                        "len %lu len %lu\n", src_offset, len, dst->len);
3814                 BUG_ON(1);
3815         }
3816         if (dst_offset + len > dst->len) {
3817                 printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move "
3818                        "len %lu len %lu\n", dst_offset, len, dst->len);
3819                 BUG_ON(1);
3820         }
3821         if (dst_offset < src_offset) {
3822                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
3823                 return;
3824         }
3825         while (len > 0) {
3826                 dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
3827                 src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
3828
3829                 dst_off_in_page = (start_offset + dst_end) &
3830                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3831                 src_off_in_page = (start_offset + src_end) &
3832                         ((unsigned long)PAGE_CACHE_SIZE - 1);
3833
3834                 cur = min_t(unsigned long, len, src_off_in_page + 1);
3835                 cur = min(cur, dst_off_in_page + 1);
3836                 move_pages(extent_buffer_page(dst, dst_i),
3837                            extent_buffer_page(dst, src_i),
3838                            dst_off_in_page - cur + 1,
3839                            src_off_in_page - cur + 1, cur);
3840
3841                 dst_end -= cur;
3842                 src_end -= cur;
3843                 len -= cur;
3844         }
3845 }
3846
3847 int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
3848 {
3849         u64 start = page_offset(page);
3850         struct extent_buffer *eb;
3851         int ret = 1;
3852         unsigned long i;
3853         unsigned long num_pages;
3854
3855         spin_lock(&tree->buffer_lock);
3856         eb = buffer_search(tree, start);
3857         if (!eb)
3858                 goto out;
3859
3860         if (atomic_read(&eb->refs) > 1) {
3861                 ret = 0;
3862                 goto out;
3863         }
3864         if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3865                 ret = 0;
3866                 goto out;
3867         }
3868         /* at this point we can safely release the extent buffer */
3869         num_pages = num_extent_pages(eb->start, eb->len);
3870         for (i = 0; i < num_pages; i++)
3871                 page_cache_release(extent_buffer_page(eb, i));
3872         rb_erase(&eb->rb_node, &tree->buffer);
3873         __free_extent_buffer(eb);
3874 out:
3875         spin_unlock(&tree->buffer_lock);
3876         return ret;
3877 }