fs/btrfs/extent_io.c

   1 #include <linux/bitops.h>
   2 #include <linux/slab.h>
   3 #include <linux/bio.h>
   4 #include <linux/mm.h>
   5 #include <linux/pagemap.h>
   6 #include <linux/page-flags.h>
   7 #include <linux/spinlock.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/swap.h>
  10 #include <linux/writeback.h>
  11 #include <linux/pagevec.h>
  12 #include <linux/prefetch.h>
  13 #include <linux/cleancache.h>
  14 #include "extent_io.h"
  15 #include "extent_map.h"
  16 #include "ctree.h"
  17 #include "btrfs_inode.h"
  18 #include "volumes.h"
  19 #include "check-integrity.h"
  20 #include "locking.h"
  21 #include "rcu-string.h"
  22 #include "backref.h"
  23
  24 static struct kmem_cache *extent_state_cache;
  25 static struct kmem_cache *extent_buffer_cache;
  26 static struct bio_set *btrfs_bioset;
  27
  28 static inline bool extent_state_in_tree(const struct extent_state *state)
  29 {
  30         return !RB_EMPTY_NODE(&state->rb_node);
  31 }
  32
  33 #ifdef CONFIG_BTRFS_DEBUG
  34 static LIST_HEAD(buffers);
  35 static LIST_HEAD(states);
  36
  37 static DEFINE_SPINLOCK(leak_lock);
  38
  39 static inline
  40 void btrfs_leak_debug_add(struct list_head *new, struct list_head *head)
  41 {
  42         unsigned long flags;
  43
  44         spin_lock_irqsave(&leak_lock, flags);
  45         list_add(new, head);
  46         spin_unlock_irqrestore(&leak_lock, flags);
  47 }
  48
  49 static inline
  50 void btrfs_leak_debug_del(struct list_head *entry)
  51 {
  52         unsigned long flags;
  53
  54         spin_lock_irqsave(&leak_lock, flags);
  55         list_del(entry);
  56         spin_unlock_irqrestore(&leak_lock, flags);
  57 }
  58
  59 static inline
  60 void btrfs_leak_debug_check(void)
  61 {
  62         struct extent_state *state;
  63         struct extent_buffer *eb;
  64
  65         while (!list_empty(&states)) {
  66                 state = list_entry(states.next, struct extent_state, leak_list);
  67                 pr_err("BTRFS: state leak: start %llu end %llu state %lu in tree %d refs %d\n",
  68                        state->start, state->end, state->state,
  69                        extent_state_in_tree(state),
  70                        atomic_read(&state->refs));
  71                 list_del(&state->leak_list);
  72                 kmem_cache_free(extent_state_cache, state);
  73         }
  74
  75         while (!list_empty(&buffers)) {
  76                 eb = list_entry(buffers.next, struct extent_buffer, leak_list);
  77                 printk(KERN_ERR "BTRFS: buffer leak start %llu len %lu "
  78                        "refs %d\n",
  79                        eb->start, eb->len, atomic_read(&eb->refs));
  80                 list_del(&eb->leak_list);
  81                 kmem_cache_free(extent_buffer_cache, eb);
  82         }
  83 }
  84
  85 #define btrfs_debug_check_extent_io_range(tree, start, end)             \
  86         __btrfs_debug_check_extent_io_range(__func__, (tree), (start), (end))
  87 static inline void __btrfs_debug_check_extent_io_range(const char *caller,
  88                 struct extent_io_tree *tree, u64 start, u64 end)
  89 {
  90         struct inode *inode;
  91         u64 isize;
  92
  93         if (!tree->mapping)
  94                 return;
  95
  96         inode = tree->mapping->host;
  97         isize = i_size_read(inode);
  98         if (end >= PAGE_SIZE && (end % 2) == 0 && end != isize - 1) {
  99                 printk_ratelimited(KERN_DEBUG
 100                     "BTRFS: %s: ino %llu isize %llu odd range [%llu,%llu]\n",
 101                                 caller, btrfs_ino(inode), isize, start, end);
 102         }
 103 }
 104 #else
 105 #define btrfs_leak_debug_add(new, head) do {} while (0)
 106 #define btrfs_leak_debug_del(entry)     do {} while (0)
 107 #define btrfs_leak_debug_check()        do {} while (0)
 108 #define btrfs_debug_check_extent_io_range(c, s, e)      do {} while (0)
 109 #endif
 110
 111 #define BUFFER_LRU_MAX 64
 112
 113 struct tree_entry {
 114         u64 start;
 115         u64 end;
 116         struct rb_node rb_node;
 117 };
 118
 119 struct extent_page_data {
 120         struct bio *bio;
 121         struct extent_io_tree *tree;
 122         get_extent_t *get_extent;
 123         unsigned long bio_flags;
 124
 125         /* tells writepage not to lock the state bits for this range
 126          * it still does the unlocking
 127          */
 128         unsigned int extent_locked:1;
 129
 130         /* tells the submit_bio code to use a WRITE_SYNC */
 131         unsigned int sync_io:1;
 132 };
 133
 134 static noinline void flush_write_bio(void *data);
 135 static inline struct btrfs_fs_info *
 136 tree_fs_info(struct extent_io_tree *tree)
 137 {
 138         if (!tree->mapping)
 139                 return NULL;
 140         return btrfs_sb(tree->mapping->host->i_sb);
 141 }
 142
 143 int __init extent_io_init(void)
 144 {
 145         extent_state_cache = kmem_cache_create("btrfs_extent_state",
 146                         sizeof(struct extent_state), 0,
 147                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 148         if (!extent_state_cache)
 149                 return -ENOMEM;
 150
 151         extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
 152                         sizeof(struct extent_buffer), 0,
 153                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 154         if (!extent_buffer_cache)
 155                 goto free_state_cache;
 156
 157         btrfs_bioset = bioset_create(BIO_POOL_SIZE,
 158                                      offsetof(struct btrfs_io_bio, bio));
 159         if (!btrfs_bioset)
 160                 goto free_buffer_cache;
 161
 162         if (bioset_integrity_create(btrfs_bioset, BIO_POOL_SIZE))
 163                 goto free_bioset;
 164
 165         return 0;
 166
 167 free_bioset:
 168         bioset_free(btrfs_bioset);
 169         btrfs_bioset = NULL;
 170
 171 free_buffer_cache:
 172         kmem_cache_destroy(extent_buffer_cache);
 173         extent_buffer_cache = NULL;
 174
 175 free_state_cache:
 176         kmem_cache_destroy(extent_state_cache);
 177         extent_state_cache = NULL;
 178         return -ENOMEM;
 179 }
 180
 181 void extent_io_exit(void)
 182 {
 183         btrfs_leak_debug_check();
 184
 185         /*
 186          * Make sure all delayed rcu free are flushed before we
 187          * destroy caches.
 188          */
 189         rcu_barrier();
 190         if (extent_state_cache)
 191                 kmem_cache_destroy(extent_state_cache);
 192         if (extent_buffer_cache)
 193                 kmem_cache_destroy(extent_buffer_cache);
 194         if (btrfs_bioset)
 195                 bioset_free(btrfs_bioset);
 196 }
 197
 198 void extent_io_tree_init(struct extent_io_tree *tree,
 199                          struct address_space *mapping)
 200 {
 201         tree->state = RB_ROOT;
 202         tree->ops = NULL;
 203         tree->dirty_bytes = 0;
 204         spin_lock_init(&tree->lock);
 205         tree->mapping = mapping;
 206 }
 207
 208 static struct extent_state *alloc_extent_state(gfp_t mask)
 209 {
 210         struct extent_state *state;
 211
 212         state = kmem_cache_alloc(extent_state_cache, mask);
 213         if (!state)
 214                 return state;
 215         state->state = 0;
 216         state->private = 0;
 217         RB_CLEAR_NODE(&state->rb_node);
 218         btrfs_leak_debug_add(&state->leak_list, &states);
 219         atomic_set(&state->refs, 1);
 220         init_waitqueue_head(&state->wq);
 221         trace_alloc_extent_state(state, mask, _RET_IP_);
 222         return state;
 223 }
 224
 225 void free_extent_state(struct extent_state *state)
 226 {
 227         if (!state)
 228                 return;
 229         if (atomic_dec_and_test(&state->refs)) {
 230                 WARN_ON(extent_state_in_tree(state));
 231                 btrfs_leak_debug_del(&state->leak_list);
 232                 trace_free_extent_state(state, _RET_IP_);
 233                 kmem_cache_free(extent_state_cache, state);
 234         }
 235 }
 236
 237 static struct rb_node *tree_insert(struct rb_root *root,
 238                                    struct rb_node *search_start,
 239                                    u64 offset,
 240                                    struct rb_node *node,
 241                                    struct rb_node ***p_in,
 242                                    struct rb_node **parent_in)
 243 {
 244         struct rb_node **p;
 245         struct rb_node *parent = NULL;
 246         struct tree_entry *entry;
 247
 248         if (p_in && parent_in) {
 249                 p = *p_in;
 250                 parent = *parent_in;
 251                 goto do_insert;
 252         }
 253
 254         p = search_start ? &search_start : &root->rb_node;
 255         while (*p) {
 256                 parent = *p;
 257                 entry = rb_entry(parent, struct tree_entry, rb_node);
 258
 259                 if (offset < entry->start)
 260                         p = &(*p)->rb_left;
 261                 else if (offset > entry->end)
 262                         p = &(*p)->rb_right;
 263                 else
 264                         return parent;
 265         }
 266
 267 do_insert:
 268         rb_link_node(node, parent, p);
 269         rb_insert_color(node, root);
 270         return NULL;
 271 }
 272
 273 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 274                                       struct rb_node **prev_ret,
 275                                       struct rb_node **next_ret,
 276                                       struct rb_node ***p_ret,
 277                                       struct rb_node **parent_ret)
 278 {
 279         struct rb_root *root = &tree->state;
 280         struct rb_node **n = &root->rb_node;
 281         struct rb_node *prev = NULL;
 282         struct rb_node *orig_prev = NULL;
 283         struct tree_entry *entry;
 284         struct tree_entry *prev_entry = NULL;
 285
 286         while (*n) {
 287                 prev = *n;
 288                 entry = rb_entry(prev, struct tree_entry, rb_node);
 289                 prev_entry = entry;
 290
 291                 if (offset < entry->start)
 292                         n = &(*n)->rb_left;
 293                 else if (offset > entry->end)
 294                         n = &(*n)->rb_right;
 295                 else
 296                         return *n;
 297         }
 298
 299         if (p_ret)
 300                 *p_ret = n;
 301         if (parent_ret)
 302                 *parent_ret = prev;
 303
 304         if (prev_ret) {
 305                 orig_prev = prev;
 306                 while (prev && offset > prev_entry->end) {
 307                         prev = rb_next(prev);
 308                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 309                 }
 310                 *prev_ret = prev;
 311                 prev = orig_prev;
 312         }
 313
 314         if (next_ret) {
 315                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 316                 while (prev && offset < prev_entry->start) {
 317                         prev = rb_prev(prev);
 318                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 319                 }
 320                 *next_ret = prev;
 321         }
 322         return NULL;
 323 }
 324
 325 static inline struct rb_node *
 326 tree_search_for_insert(struct extent_io_tree *tree,
 327                        u64 offset,
 328                        struct rb_node ***p_ret,
 329                        struct rb_node **parent_ret)
 330 {
 331         struct rb_node *prev = NULL;
 332         struct rb_node *ret;
 333
 334         ret = __etree_search(tree, offset, &prev, NULL, p_ret, parent_ret);
 335         if (!ret)
 336                 return prev;
 337         return ret;
 338 }
 339
 340 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 341                                           u64 offset)
 342 {
 343         return tree_search_for_insert(tree, offset, NULL, NULL);
 344 }
 345
 346 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
 347                      struct extent_state *other)
 348 {
 349         if (tree->ops && tree->ops->merge_extent_hook)
 350                 tree->ops->merge_extent_hook(tree->mapping->host, new,
 351                                              other);
 352 }
 353
 354 /*
 355  * utility function to look for merge candidates inside a given range.
 356  * Any extents with matching state are merged together into a single
 357  * extent in the tree.  Extents with EXTENT_IO in their state field
 358  * are not merged because the end_io handlers need to be able to do
 359  * operations on them without sleeping (or doing allocations/splits).
 360  *
 361  * This should be called with the tree lock held.
 362  */
 363 static void merge_state(struct extent_io_tree *tree,
 364                         struct extent_state *state)
 365 {
 366         struct extent_state *other;
 367         struct rb_node *other_node;
 368
 369         if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 370                 return;
 371
 372         other_node = rb_prev(&state->rb_node);
 373         if (other_node) {
 374                 other = rb_entry(other_node, struct extent_state, rb_node);
 375                 if (other->end == state->start - 1 &&
 376                     other->state == state->state) {
 377                         merge_cb(tree, state, other);
 378                         state->start = other->start;
 379                         rb_erase(&other->rb_node, &tree->state);
 380                         RB_CLEAR_NODE(&other->rb_node);
 381                         free_extent_state(other);
 382                 }
 383         }
 384         other_node = rb_next(&state->rb_node);
 385         if (other_node) {
 386                 other = rb_entry(other_node, struct extent_state, rb_node);
 387                 if (other->start == state->end + 1 &&
 388                     other->state == state->state) {
 389                         merge_cb(tree, state, other);
 390                         state->end = other->end;
 391                         rb_erase(&other->rb_node, &tree->state);
 392                         RB_CLEAR_NODE(&other->rb_node);
 393                         free_extent_state(other);
 394                 }
 395         }
 396 }
 397
 398 static void set_state_cb(struct extent_io_tree *tree,
 399                          struct extent_state *state, unsigned long *bits)
 400 {
 401         if (tree->ops && tree->ops->set_bit_hook)
 402                 tree->ops->set_bit_hook(tree->mapping->host, state, bits);
 403 }
 404
 405 static void clear_state_cb(struct extent_io_tree *tree,
 406                            struct extent_state *state, unsigned long *bits)
 407 {
 408         if (tree->ops && tree->ops->clear_bit_hook)
 409                 tree->ops->clear_bit_hook(tree->mapping->host, state, bits);
 410 }
 411
 412 static void set_state_bits(struct extent_io_tree *tree,
 413                            struct extent_state *state, unsigned long *bits);
 414
 415 /*
 416  * insert an extent_state struct into the tree.  'bits' are set on the
 417  * struct before it is inserted.
 418  *
 419  * This may return -EEXIST if the extent is already there, in which case the
 420  * state struct is freed.
 421  *
 422  * The tree lock is not taken internally.  This is a utility function and
 423  * probably isn't what you want to call (see set/clear_extent_bit).
 424  */
 425 static int insert_state(struct extent_io_tree *tree,
 426                         struct extent_state *state, u64 start, u64 end,
 427                         struct rb_node ***p,
 428                         struct rb_node **parent,
 429                         unsigned long *bits)
 430 {
 431         struct rb_node *node;
 432
 433         if (end < start)
 434                 WARN(1, KERN_ERR "BTRFS: end < start %llu %llu\n",
 435                        end, start);
 436         state->start = start;
 437         state->end = end;
 438
 439         set_state_bits(tree, state, bits);
 440
 441         node = tree_insert(&tree->state, NULL, end, &state->rb_node, p, parent);
 442         if (node) {
 443                 struct extent_state *found;
 444                 found = rb_entry(node, struct extent_state, rb_node);
 445                 printk(KERN_ERR "BTRFS: found node %llu %llu on insert of "
 446                        "%llu %llu\n",
 447                        found->start, found->end, start, end);
 448                 return -EEXIST;
 449         }
 450         merge_state(tree, state);
 451         return 0;
 452 }
 453
 454 static void split_cb(struct extent_io_tree *tree, struct extent_state *orig,
 455                      u64 split)
 456 {
 457         if (tree->ops && tree->ops->split_extent_hook)
 458                 tree->ops->split_extent_hook(tree->mapping->host, orig, split);
 459 }
 460
 461 /*
 462  * split a given extent state struct in two, inserting the preallocated
 463  * struct 'prealloc' as the newly created second half.  'split' indicates an
 464  * offset inside 'orig' where it should be split.
 465  *
 466  * Before calling,
 467  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
 468  * are two extent state structs in the tree:
 469  * prealloc: [orig->start, split - 1]
 470  * orig: [ split, orig->end ]
 471  *
 472  * The tree locks are not taken by this function. They need to be held
 473  * by the caller.
 474  */
 475 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 476                        struct extent_state *prealloc, u64 split)
 477 {
 478         struct rb_node *node;
 479
 480         split_cb(tree, orig, split);
 481
 482         prealloc->start = orig->start;
 483         prealloc->end = split - 1;
 484         prealloc->state = orig->state;
 485         orig->start = split;
 486
 487         node = tree_insert(&tree->state, &orig->rb_node, prealloc->end,
 488                            &prealloc->rb_node, NULL, NULL);
 489         if (node) {
 490                 free_extent_state(prealloc);
 491                 return -EEXIST;
 492         }
 493         return 0;
 494 }
 495
 496 static struct extent_state *next_state(struct extent_state *state)
 497 {
 498         struct rb_node *next = rb_next(&state->rb_node);
 499         if (next)
 500                 return rb_entry(next, struct extent_state, rb_node);
 501         else
 502                 return NULL;
 503 }
 504
 505 /*
 506  * utility function to clear some bits in an extent state struct.
 507  * it will optionally wake up any one waiting on this state (wake == 1).
 508  *
 509  * If no bits are set on the state struct after clearing things, the
 510  * struct is freed and removed from the tree
 511  */
 512 static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
 513                                             struct extent_state *state,
 514                                             unsigned long *bits, int wake)
 515 {
 516         struct extent_state *next;
 517         unsigned long bits_to_clear = *bits & ~EXTENT_CTLBITS;
 518
 519         if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 520                 u64 range = state->end - state->start + 1;
 521                 WARN_ON(range > tree->dirty_bytes);
 522                 tree->dirty_bytes -= range;
 523         }
 524         clear_state_cb(tree, state, bits);
 525         state->state &= ~bits_to_clear;
 526         if (wake)
 527                 wake_up(&state->wq);
 528         if (state->state == 0) {
 529                 next = next_state(state);
 530                 if (extent_state_in_tree(state)) {
 531                         rb_erase(&state->rb_node, &tree->state);
 532                         RB_CLEAR_NODE(&state->rb_node);
 533                         free_extent_state(state);
 534                 } else {
 535                         WARN_ON(1);
 536                 }
 537         } else {
 538                 merge_state(tree, state);
 539                 next = next_state(state);
 540         }
 541         return next;
 542 }
 543
 544 static struct extent_state *
 545 alloc_extent_state_atomic(struct extent_state *prealloc)
 546 {
 547         if (!prealloc)
 548                 prealloc = alloc_extent_state(GFP_ATOMIC);
 549
 550         return prealloc;
 551 }
 552
 553 static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
 554 {
 555         btrfs_panic(tree_fs_info(tree), err, "Locking error: "
 556                     "Extent tree was modified by another "
 557                     "thread while locked.");
 558 }
 559
 560 /*
 561  * clear some bits on a range in the tree.  This may require splitting
 562  * or inserting elements in the tree, so the gfp mask is used to
 563  * indicate which allocations or sleeping are allowed.
 564  *
 565  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 566  * the given range from the tree regardless of state (ie for truncate).
 567  *
 568  * the range [start, end] is inclusive.
 569  *
 570  * This takes the tree lock, and returns 0 on success and < 0 on error.
 571  */
 572 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 573                      unsigned long bits, int wake, int delete,
 574                      struct extent_state **cached_state,
 575                      gfp_t mask)
 576 {
 577         struct extent_state *state;
 578         struct extent_state *cached;
 579         struct extent_state *prealloc = NULL;
 580         struct rb_node *node;
 581         u64 last_end;
 582         int err;
 583         int clear = 0;
 584
 585         btrfs_debug_check_extent_io_range(tree, start, end);
 586
 587         if (bits & EXTENT_DELALLOC)
 588                 bits |= EXTENT_NORESERVE;
 589
 590         if (delete)
 591                 bits |= ~EXTENT_CTLBITS;
 592         bits |= EXTENT_FIRST_DELALLOC;
 593
 594         if (bits & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 595                 clear = 1;
 596 again:
 597         if (!prealloc && (mask & __GFP_WAIT)) {
 598                 prealloc = alloc_extent_state(mask);
 599                 if (!prealloc)
 600                         return -ENOMEM;
 601         }
 602
 603         spin_lock(&tree->lock);
 604         if (cached_state) {
 605                 cached = *cached_state;
 606
 607                 if (clear) {
 608                         *cached_state = NULL;
 609                         cached_state = NULL;
 610                 }
 611
 612                 if (cached && extent_state_in_tree(cached) &&
 613                     cached->start <= start && cached->end > start) {
 614                         if (clear)
 615                                 atomic_dec(&cached->refs);
 616                         state = cached;
 617                         goto hit_next;
 618                 }
 619                 if (clear)
 620                         free_extent_state(cached);
 621         }
 622         /*
 623          * this search will find the extents that end after
 624          * our range starts
 625          */
 626         node = tree_search(tree, start);
 627         if (!node)
 628                 goto out;
 629         state = rb_entry(node, struct extent_state, rb_node);
 630 hit_next:
 631         if (state->start > end)
 632                 goto out;
 633         WARN_ON(state->end < start);
 634         last_end = state->end;
 635
 636         /* the state doesn't have the wanted bits, go ahead */
 637         if (!(state->state & bits)) {
 638                 state = next_state(state);
 639                 goto next;
 640         }
 641
 642         /*
 643          *     | ---- desired range ---- |
 644          *  | state | or
 645          *  | ------------- state -------------- |
 646          *
 647          * We need to split the extent we found, and may flip
 648          * bits on second half.
 649          *
 650          * If the extent we found extends past our range, we
 651          * just split and search again.  It'll get split again
 652          * the next time though.
 653          *
 654          * If the extent we found is inside our range, we clear
 655          * the desired bit on it.
 656          */
 657
 658         if (state->start < start) {
 659                 prealloc = alloc_extent_state_atomic(prealloc);
 660                 BUG_ON(!prealloc);
 661                 err = split_state(tree, state, prealloc, start);
 662                 if (err)
 663                         extent_io_tree_panic(tree, err);
 664
 665                 prealloc = NULL;
 666                 if (err)
 667                         goto out;
 668                 if (state->end <= end) {
 669                         state = clear_state_bit(tree, state, &bits, wake);
 670                         goto next;
 671                 }
 672                 goto search_again;
 673         }
 674         /*
 675          * | ---- desired range ---- |
 676          *                        | state |
 677          * We need to split the extent, and clear the bit
 678          * on the first half
 679          */
 680         if (state->start <= end && state->end > end) {
 681                 prealloc = alloc_extent_state_atomic(prealloc);
 682                 BUG_ON(!prealloc);
 683                 err = split_state(tree, state, prealloc, end + 1);
 684                 if (err)
 685                         extent_io_tree_panic(tree, err);
 686
 687                 if (wake)
 688                         wake_up(&state->wq);
 689
 690                 clear_state_bit(tree, prealloc, &bits, wake);
 691
 692                 prealloc = NULL;
 693                 goto out;
 694         }
 695
 696         state = clear_state_bit(tree, state, &bits, wake);
 697 next:
 698         if (last_end == (u64)-1)
 699                 goto out;
 700         start = last_end + 1;
 701         if (start <= end && state && !need_resched())
 702                 goto hit_next;
 703         goto search_again;
 704
 705 out:
 706         spin_unlock(&tree->lock);
 707         if (prealloc)
 708                 free_extent_state(prealloc);
 709
 710         return 0;
 711
 712 search_again:
 713         if (start > end)
 714                 goto out;
 715         spin_unlock(&tree->lock);
 716         if (mask & __GFP_WAIT)
 717                 cond_resched();
 718         goto again;
 719 }
 720
 721 static void wait_on_state(struct extent_io_tree *tree,
 722                           struct extent_state *state)
 723                 __releases(tree->lock)
 724                 __acquires(tree->lock)
 725 {
 726         DEFINE_WAIT(wait);
 727         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 728         spin_unlock(&tree->lock);
 729         schedule();
 730         spin_lock(&tree->lock);
 731         finish_wait(&state->wq, &wait);
 732 }
 733
 734 /*
 735  * waits for one or more bits to clear on a range in the state tree.
 736  * The range [start, end] is inclusive.
 737  * The tree lock is taken by this function
 738  */
 739 static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 740                             unsigned long bits)
 741 {
 742         struct extent_state *state;
 743         struct rb_node *node;
 744
 745         btrfs_debug_check_extent_io_range(tree, start, end);
 746
 747         spin_lock(&tree->lock);
 748 again:
 749         while (1) {
 750                 /*
 751                  * this search will find all the extents that end after
 752                  * our range starts
 753                  */
 754                 node = tree_search(tree, start);
 755 process_node:
 756                 if (!node)
 757                         break;
 758
 759                 state = rb_entry(node, struct extent_state, rb_node);
 760
 761                 if (state->start > end)
 762                         goto out;
 763
 764                 if (state->state & bits) {
 765                         start = state->start;
 766                         atomic_inc(&state->refs);
 767                         wait_on_state(tree, state);
 768                         free_extent_state(state);
 769                         goto again;
 770                 }
 771                 start = state->end + 1;
 772
 773                 if (start > end)
 774                         break;
 775
 776                 if (!cond_resched_lock(&tree->lock)) {
 777                         node = rb_next(node);
 778                         goto process_node;
 779                 }
 780         }
 781 out:
 782         spin_unlock(&tree->lock);
 783 }
 784
 785 static void set_state_bits(struct extent_io_tree *tree,
 786                            struct extent_state *state,
 787                            unsigned long *bits)
 788 {
 789         unsigned long bits_to_set = *bits & ~EXTENT_CTLBITS;
 790
 791         set_state_cb(tree, state, bits);
 792         if ((bits_to_set & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 793                 u64 range = state->end - state->start + 1;
 794                 tree->dirty_bytes += range;
 795         }
 796         state->state |= bits_to_set;
 797 }
 798
 799 static void cache_state(struct extent_state *state,
 800                         struct extent_state **cached_ptr)
 801 {
 802         if (cached_ptr && !(*cached_ptr)) {
 803                 if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) {
 804                         *cached_ptr = state;
 805                         atomic_inc(&state->refs);
 806                 }
 807         }
 808 }
 809
 810 /*
 811  * set some bits on a range in the tree.  This may require allocations or
 812  * sleeping, so the gfp mask is used to indicate what is allowed.
 813  *
 814  * If any of the exclusive bits are set, this will fail with -EEXIST if some
 815  * part of the range already has the desired bits set.  The start of the
 816  * existing range is returned in failed_start in this case.
 817  *
 818  * [start, end] is inclusive This takes the tree lock.
 819  */
 820
 821 static int __must_check
 822 __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 823                  unsigned long bits, unsigned long exclusive_bits,
 824                  u64 *failed_start, struct extent_state **cached_state,
 825                  gfp_t mask)
 826 {
 827         struct extent_state *state;
 828         struct extent_state *prealloc = NULL;
 829         struct rb_node *node;
 830         struct rb_node **p;
 831         struct rb_node *parent;
 832         int err = 0;
 833         u64 last_start;
 834         u64 last_end;
 835
 836         btrfs_debug_check_extent_io_range(tree, start, end);
 837
 838         bits |= EXTENT_FIRST_DELALLOC;
 839 again:
 840         if (!prealloc && (mask & __GFP_WAIT)) {
 841                 prealloc = alloc_extent_state(mask);
 842                 BUG_ON(!prealloc);
 843         }
 844
 845         spin_lock(&tree->lock);
 846         if (cached_state && *cached_state) {
 847                 state = *cached_state;
 848                 if (state->start <= start && state->end > start &&
 849                     extent_state_in_tree(state)) {
 850                         node = &state->rb_node;
 851                         goto hit_next;
 852                 }
 853         }
 854         /*
 855          * this search will find all the extents that end after
 856          * our range starts.
 857          */
 858         node = tree_search_for_insert(tree, start, &p, &parent);
 859         if (!node) {
 860                 prealloc = alloc_extent_state_atomic(prealloc);
 861                 BUG_ON(!prealloc);
 862                 err = insert_state(tree, prealloc, start, end,
 863                                    &p, &parent, &bits);
 864                 if (err)
 865                         extent_io_tree_panic(tree, err);
 866
 867                 cache_state(prealloc, cached_state);
 868                 prealloc = NULL;
 869                 goto out;
 870         }
 871         state = rb_entry(node, struct extent_state, rb_node);
 872 hit_next:
 873         last_start = state->start;
 874         last_end = state->end;
 875
 876         /*
 877          * | ---- desired range ---- |
 878          * | state |
 879          *
 880          * Just lock what we found and keep going
 881          */
 882         if (state->start == start && state->end <= end) {
 883                 if (state->state & exclusive_bits) {
 884                         *failed_start = state->start;
 885                         err = -EEXIST;
 886                         goto out;
 887                 }
 888
 889                 set_state_bits(tree, state, &bits);
 890                 cache_state(state, cached_state);
 891                 merge_state(tree, state);
 892                 if (last_end == (u64)-1)
 893                         goto out;
 894                 start = last_end + 1;
 895                 state = next_state(state);
 896                 if (start < end && state && state->start == start &&
 897                     !need_resched())
 898                         goto hit_next;
 899                 goto search_again;
 900         }
 901
 902         /*
 903          *     | ---- desired range ---- |
 904          * | state |
 905          *   or
 906          * | ------------- state -------------- |
 907          *
 908          * We need to split the extent we found, and may flip bits on
 909          * second half.
 910          *
 911          * If the extent we found extends past our
 912          * range, we just split and search again.  It'll get split
 913          * again the next time though.
 914          *
 915          * If the extent we found is inside our range, we set the
 916          * desired bit on it.
 917          */
 918         if (state->start < start) {
 919                 if (state->state & exclusive_bits) {
 920                         *failed_start = start;
 921                         err = -EEXIST;
 922                         goto out;
 923                 }
 924
 925                 prealloc = alloc_extent_state_atomic(prealloc);
 926                 BUG_ON(!prealloc);
 927                 err = split_state(tree, state, prealloc, start);
 928                 if (err)
 929                         extent_io_tree_panic(tree, err);
 930
 931                 prealloc = NULL;
 932                 if (err)
 933                         goto out;
 934                 if (state->end <= end) {
 935                         set_state_bits(tree, state, &bits);
 936                         cache_state(state, cached_state);
 937                         merge_state(tree, state);
 938                         if (last_end == (u64)-1)
 939                                 goto out;
 940                         start = last_end + 1;
 941                         state = next_state(state);
 942                         if (start < end && state && state->start == start &&
 943                             !need_resched())
 944                                 goto hit_next;
 945                 }
 946                 goto search_again;
 947         }
 948         /*
 949          * | ---- desired range ---- |
 950          *     | state | or               | state |
 951          *
 952          * There's a hole, we need to insert something in it and
 953          * ignore the extent we found.
 954          */
 955         if (state->start > start) {
 956                 u64 this_end;
 957                 if (end < last_start)
 958                         this_end = end;
 959                 else
 960                         this_end = last_start - 1;
 961
 962                 prealloc = alloc_extent_state_atomic(prealloc);
 963                 BUG_ON(!prealloc);
 964
 965                 /*
 966                  * Avoid to free 'prealloc' if it can be merged with
 967                  * the later extent.
 968                  */
 969                 err = insert_state(tree, prealloc, start, this_end,
 970                                    NULL, NULL, &bits);
 971                 if (err)
 972                         extent_io_tree_panic(tree, err);
 973
 974                 cache_state(prealloc, cached_state);
 975                 prealloc = NULL;
 976                 start = this_end + 1;
 977                 goto search_again;
 978         }
 979         /*
 980          * | ---- desired range ---- |
 981          *                        | state |
 982          * We need to split the extent, and set the bit
 983          * on the first half
 984          */
 985         if (state->start <= end && state->end > end) {
 986                 if (state->state & exclusive_bits) {
 987                         *failed_start = start;
 988                         err = -EEXIST;
 989                         goto out;
 990                 }
 991
 992                 prealloc = alloc_extent_state_atomic(prealloc);
 993                 BUG_ON(!prealloc);
 994                 err = split_state(tree, state, prealloc, end + 1);
 995                 if (err)
 996                         extent_io_tree_panic(tree, err);
 997
 998                 set_state_bits(tree, prealloc, &bits);
 999                 cache_state(prealloc, cached_state);
1000                 merge_state(tree, prealloc);
1001                 prealloc = NULL;
1002                 goto out;
1003         }
1004
1005         goto search_again;
1006
1007 out:
1008         spin_unlock(&tree->lock);
1009         if (prealloc)
1010                 free_extent_state(prealloc);
1011
1012         return err;
1013
1014 search_again:
1015         if (start > end)
1016                 goto out;
1017         spin_unlock(&tree->lock);
1018         if (mask & __GFP_WAIT)
1019                 cond_resched();
1020         goto again;
1021 }
1022
1023 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1024                    unsigned long bits, u64 * failed_start,
1025                    struct extent_state **cached_state, gfp_t mask)
1026 {
1027         return __set_extent_bit(tree, start, end, bits, 0, failed_start,
1028                                 cached_state, mask);
1029 }
1030
1031
1032 /**
1033  * convert_extent_bit - convert all bits in a given range from one bit to
1034  *                      another
1035  * @tree:       the io tree to search
1036  * @start:      the start offset in bytes
1037  * @end:        the end offset in bytes (inclusive)
1038  * @bits:       the bits to set in this range
1039  * @clear_bits: the bits to clear in this range
1040  * @cached_state:       state that we're going to cache
1041  * @mask:       the allocation mask
1042  *
1043  * This will go through and set bits for the given range.  If any states exist
1044  * already in this range they are set with the given bit and cleared of the
1045  * clear_bits.  This is only meant to be used by things that are mergeable, ie
1046  * converting from say DELALLOC to DIRTY.  This is not meant to be used with
1047  * boundary bits like LOCK.
1048  */
1049 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1050                        unsigned long bits, unsigned long clear_bits,
1051                        struct extent_state **cached_state, gfp_t mask)
1052 {
1053         struct extent_state *state;
1054         struct extent_state *prealloc = NULL;
1055         struct rb_node *node;
1056         struct rb_node **p;
1057         struct rb_node *parent;
1058         int err = 0;
1059         u64 last_start;
1060         u64 last_end;
1061
1062         btrfs_debug_check_extent_io_range(tree, start, end);
1063
1064 again:
1065         if (!prealloc && (mask & __GFP_WAIT)) {
1066                 prealloc = alloc_extent_state(mask);
1067                 if (!prealloc)
1068                         return -ENOMEM;
1069         }
1070
1071         spin_lock(&tree->lock);
1072         if (cached_state && *cached_state) {
1073                 state = *cached_state;
1074                 if (state->start <= start && state->end > start &&
1075                     extent_state_in_tree(state)) {
1076                         node = &state->rb_node;
1077                         goto hit_next;
1078                 }
1079         }
1080
1081         /*
1082          * this search will find all the extents that end after
1083          * our range starts.
1084          */
1085         node = tree_search_for_insert(tree, start, &p, &parent);
1086         if (!node) {
1087                 prealloc = alloc_extent_state_atomic(prealloc);
1088                 if (!prealloc) {
1089                         err = -ENOMEM;
1090                         goto out;
1091                 }
1092                 err = insert_state(tree, prealloc, start, end,
1093                                    &p, &parent, &bits);
1094                 if (err)
1095                         extent_io_tree_panic(tree, err);
1096                 cache_state(prealloc, cached_state);
1097                 prealloc = NULL;
1098                 goto out;
1099         }
1100         state = rb_entry(node, struct extent_state, rb_node);
1101 hit_next:
1102         last_start = state->start;
1103         last_end = state->end;
1104
1105         /*
1106          * | ---- desired range ---- |
1107          * | state |
1108          *
1109          * Just lock what we found and keep going
1110          */
1111         if (state->start == start && state->end <= end) {
1112                 set_state_bits(tree, state, &bits);
1113                 cache_state(state, cached_state);
1114                 state = clear_state_bit(tree, state, &clear_bits, 0);
1115                 if (last_end == (u64)-1)
1116                         goto out;
1117                 start = last_end + 1;
1118                 if (start < end && state && state->start == start &&
1119                     !need_resched())
1120                         goto hit_next;
1121                 goto search_again;
1122         }
1123
1124         /*
1125          *     | ---- desired range ---- |
1126          * | state |
1127          *   or
1128          * | ------------- state -------------- |
1129          *
1130          * We need to split the extent we found, and may flip bits on
1131          * second half.
1132          *
1133          * If the extent we found extends past our
1134          * range, we just split and search again.  It'll get split
1135          * again the next time though.
1136          *
1137          * If the extent we found is inside our range, we set the
1138          * desired bit on it.
1139          */
1140         if (state->start < start) {
1141                 prealloc = alloc_extent_state_atomic(prealloc);
1142                 if (!prealloc) {
1143                         err = -ENOMEM;
1144                         goto out;
1145                 }
1146                 err = split_state(tree, state, prealloc, start);
1147                 if (err)
1148                         extent_io_tree_panic(tree, err);
1149                 prealloc = NULL;
1150                 if (err)
1151                         goto out;
1152                 if (state->end <= end) {
1153                         set_state_bits(tree, state, &bits);
1154                         cache_state(state, cached_state);
1155                         state = clear_state_bit(tree, state, &clear_bits, 0);
1156                         if (last_end == (u64)-1)
1157                                 goto out;
1158                         start = last_end + 1;
1159                         if (start < end && state && state->start == start &&
1160                             !need_resched())
1161                                 goto hit_next;
1162                 }
1163                 goto search_again;
1164         }
1165         /*
1166          * | ---- desired range ---- |
1167          *     | state | or               | state |
1168          *
1169          * There's a hole, we need to insert something in it and
1170          * ignore the extent we found.
1171          */
1172         if (state->start > start) {
1173                 u64 this_end;
1174                 if (end < last_start)
1175                         this_end = end;
1176                 else
1177                         this_end = last_start - 1;
1178
1179                 prealloc = alloc_extent_state_atomic(prealloc);
1180                 if (!prealloc) {
1181                         err = -ENOMEM;
1182                         goto out;
1183                 }
1184
1185                 /*
1186                  * Avoid to free 'prealloc' if it can be merged with
1187                  * the later extent.
1188                  */
1189                 err = insert_state(tree, prealloc, start, this_end,
1190                                    NULL, NULL, &bits);
1191                 if (err)
1192                         extent_io_tree_panic(tree, err);
1193                 cache_state(prealloc, cached_state);
1194                 prealloc = NULL;
1195                 start = this_end + 1;
1196                 goto search_again;
1197         }
1198         /*
1199          * | ---- desired range ---- |
1200          *                        | state |
1201          * We need to split the extent, and set the bit
1202          * on the first half
1203          */
1204         if (state->start <= end && state->end > end) {
1205                 prealloc = alloc_extent_state_atomic(prealloc);
1206                 if (!prealloc) {
1207                         err = -ENOMEM;
1208                         goto out;
1209                 }
1210
1211                 err = split_state(tree, state, prealloc, end + 1);
1212                 if (err)
1213                         extent_io_tree_panic(tree, err);
1214
1215                 set_state_bits(tree, prealloc, &bits);
1216                 cache_state(prealloc, cached_state);
1217                 clear_state_bit(tree, prealloc, &clear_bits, 0);
1218                 prealloc = NULL;
1219                 goto out;
1220         }
1221
1222         goto search_again;
1223
1224 out:
1225         spin_unlock(&tree->lock);
1226         if (prealloc)
1227                 free_extent_state(prealloc);
1228
1229         return err;
1230
1231 search_again:
1232         if (start > end)
1233                 goto out;
1234         spin_unlock(&tree->lock);
1235         if (mask & __GFP_WAIT)
1236                 cond_resched();
1237         goto again;
1238 }
1239
1240 /* wrappers around set/clear extent bit */
1241 int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
1242                      gfp_t mask)
1243 {
1244         return set_extent_bit(tree, start, end, EXTENT_DIRTY, NULL,
1245                               NULL, mask);
1246 }
1247
1248 int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1249                     unsigned long bits, gfp_t mask)
1250 {
1251         return set_extent_bit(tree, start, end, bits, NULL,
1252                               NULL, mask);
1253 }
1254
1255 int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1256                       unsigned long bits, gfp_t mask)
1257 {
1258         return clear_extent_bit(tree, start, end, bits, 0, 0, NULL, mask);
1259 }
1260
1261 int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
1262                         struct extent_state **cached_state, gfp_t mask)
1263 {
1264         return set_extent_bit(tree, start, end,
1265                               EXTENT_DELALLOC | EXTENT_UPTODATE,
1266                               NULL, cached_state, mask);
1267 }
1268
1269 int set_extent_defrag(struct extent_io_tree *tree, u64 start, u64 end,
1270                       struct extent_state **cached_state, gfp_t mask)
1271 {
1272         return set_extent_bit(tree, start, end,
1273                               EXTENT_DELALLOC | EXTENT_UPTODATE | EXTENT_DEFRAG,
1274                               NULL, cached_state, mask);
1275 }
1276
1277 int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
1278                        gfp_t mask)
1279 {
1280         return clear_extent_bit(tree, start, end,
1281                                 EXTENT_DIRTY | EXTENT_DELALLOC |
1282                                 EXTENT_DO_ACCOUNTING, 0, 0, NULL, mask);
1283 }
1284
1285 int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
1286                      gfp_t mask)
1287 {
1288         return set_extent_bit(tree, start, end, EXTENT_NEW, NULL,
1289                               NULL, mask);
1290 }
1291
1292 int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
1293                         struct extent_state **cached_state, gfp_t mask)
1294 {
1295         return set_extent_bit(tree, start, end, EXTENT_UPTODATE, NULL,
1296                               cached_state, mask);
1297 }
1298
1299 int clear_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
1300                           struct extent_state **cached_state, gfp_t mask)
1301 {
1302         return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
1303                                 cached_state, mask);
1304 }
1305
1306 /*
1307  * either insert or lock state struct between start and end use mask to tell
1308  * us if waiting is desired.
1309  */
1310 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1311                      unsigned long bits, struct extent_state **cached_state)
1312 {
1313         int err;
1314         u64 failed_start;
1315         while (1) {
1316                 err = __set_extent_bit(tree, start, end, EXTENT_LOCKED | bits,
1317                                        EXTENT_LOCKED, &failed_start,
1318                                        cached_state, GFP_NOFS);
1319                 if (err == -EEXIST) {
1320                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1321                         start = failed_start;
1322                 } else
1323                         break;
1324                 WARN_ON(start > end);
1325         }
1326         return err;
1327 }
1328
1329 int lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1330 {
1331         return lock_extent_bits(tree, start, end, 0, NULL);
1332 }
1333
1334 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1335 {
1336         int err;
1337         u64 failed_start;
1338
1339         err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1340                                &failed_start, NULL, GFP_NOFS);
1341         if (err == -EEXIST) {
1342                 if (failed_start > start)
1343                         clear_extent_bit(tree, start, failed_start - 1,
1344                                          EXTENT_LOCKED, 1, 0, NULL, GFP_NOFS);
1345                 return 0;
1346         }
1347         return 1;
1348 }
1349
1350 int unlock_extent_cached(struct extent_io_tree *tree, u64 start, u64 end,
1351                          struct extent_state **cached, gfp_t mask)
1352 {
1353         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
1354                                 mask);
1355 }
1356
1357 int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1358 {
1359         return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL,
1360                                 GFP_NOFS);
1361 }
1362
1363 int extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
1364 {
1365         unsigned long index = start >> PAGE_CACHE_SHIFT;
1366         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1367         struct page *page;
1368
1369         while (index <= end_index) {
1370                 page = find_get_page(inode->i_mapping, index);
1371                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1372                 clear_page_dirty_for_io(page);
1373                 page_cache_release(page);
1374                 index++;
1375         }
1376         return 0;
1377 }
1378
1379 int extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
1380 {
1381         unsigned long index = start >> PAGE_CACHE_SHIFT;
1382         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1383         struct page *page;
1384
1385         while (index <= end_index) {
1386                 page = find_get_page(inode->i_mapping, index);
1387                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1388                 account_page_redirty(page);
1389                 __set_page_dirty_nobuffers(page);
1390                 page_cache_release(page);
1391                 index++;
1392         }
1393         return 0;
1394 }
1395
1396 /*
1397  * helper function to set both pages and extents in the tree writeback
1398  */
1399 static int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1400 {
1401         unsigned long index = start >> PAGE_CACHE_SHIFT;
1402         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1403         struct page *page;
1404
1405         while (index <= end_index) {
1406                 page = find_get_page(tree->mapping, index);
1407                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1408                 set_page_writeback(page);
1409                 page_cache_release(page);
1410                 index++;
1411         }
1412         return 0;
1413 }
1414
1415 /* find the first state struct with 'bits' set after 'start', and
1416  * return it.  tree->lock must be held.  NULL will returned if
1417  * nothing was found after 'start'
1418  */
1419 static struct extent_state *
1420 find_first_extent_bit_state(struct extent_io_tree *tree,
1421                             u64 start, unsigned long bits)
1422 {
1423         struct rb_node *node;
1424         struct extent_state *state;
1425
1426         /*
1427          * this search will find all the extents that end after
1428          * our range starts.
1429          */
1430         node = tree_search(tree, start);
1431         if (!node)
1432                 goto out;
1433
1434         while (1) {
1435                 state = rb_entry(node, struct extent_state, rb_node);
1436                 if (state->end >= start && (state->state & bits))
1437                         return state;
1438
1439                 node = rb_next(node);
1440                 if (!node)
1441                         break;
1442         }
1443 out:
1444         return NULL;
1445 }
1446
1447 /*
1448  * find the first offset in the io tree with 'bits' set. zero is
1449  * returned if we find something, and *start_ret and *end_ret are
1450  * set to reflect the state struct that was found.
1451  *
1452  * If nothing was found, 1 is returned. If found something, return 0.
1453  */
1454 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1455                           u64 *start_ret, u64 *end_ret, unsigned long bits,
1456                           struct extent_state **cached_state)
1457 {
1458         struct extent_state *state;
1459         struct rb_node *n;
1460         int ret = 1;
1461
1462         spin_lock(&tree->lock);
1463         if (cached_state && *cached_state) {
1464                 state = *cached_state;
1465                 if (state->end == start - 1 && extent_state_in_tree(state)) {
1466                         n = rb_next(&state->rb_node);
1467                         while (n) {
1468                                 state = rb_entry(n, struct extent_state,
1469                                                  rb_node);
1470                                 if (state->state & bits)
1471                                         goto got_it;
1472                                 n = rb_next(n);
1473                         }
1474                         free_extent_state(*cached_state);
1475                         *cached_state = NULL;
1476                         goto out;
1477                 }
1478                 free_extent_state(*cached_state);
1479                 *cached_state = NULL;
1480         }
1481
1482         state = find_first_extent_bit_state(tree, start, bits);
1483 got_it:
1484         if (state) {
1485                 cache_state(state, cached_state);
1486                 *start_ret = state->start;
1487                 *end_ret = state->end;
1488                 ret = 0;
1489         }
1490 out:
1491         spin_unlock(&tree->lock);
1492         return ret;
1493 }
1494
1495 /*
1496  * find a contiguous range of bytes in the file marked as delalloc, not
1497  * more than 'max_bytes'.  start and end are used to return the range,
1498  *
1499  * 1 is returned if we find something, 0 if nothing was in the tree
1500  */
1501 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1502                                         u64 *start, u64 *end, u64 max_bytes,
1503                                         struct extent_state **cached_state)
1504 {
1505         struct rb_node *node;
1506         struct extent_state *state;
1507         u64 cur_start = *start;
1508         u64 found = 0;
1509         u64 total_bytes = 0;
1510
1511         spin_lock(&tree->lock);
1512
1513         /*
1514          * this search will find all the extents that end after
1515          * our range starts.
1516          */
1517         node = tree_search(tree, cur_start);
1518         if (!node) {
1519                 if (!found)
1520                         *end = (u64)-1;
1521                 goto out;
1522         }
1523
1524         while (1) {
1525                 state = rb_entry(node, struct extent_state, rb_node);
1526                 if (found && (state->start != cur_start ||
1527                               (state->state & EXTENT_BOUNDARY))) {
1528                         goto out;
1529                 }
1530                 if (!(state->state & EXTENT_DELALLOC)) {
1531                         if (!found)
1532                                 *end = state->end;
1533                         goto out;
1534                 }
1535                 if (!found) {
1536                         *start = state->start;
1537                         *cached_state = state;
1538                         atomic_inc(&state->refs);
1539                 }
1540                 found++;
1541                 *end = state->end;
1542                 cur_start = state->end + 1;
1543                 node = rb_next(node);
1544                 total_bytes += state->end - state->start + 1;
1545                 if (total_bytes >= max_bytes)
1546                         break;
1547                 if (!node)
1548                         break;
1549         }
1550 out:
1551         spin_unlock(&tree->lock);
1552         return found;
1553 }
1554
1555 static noinline void __unlock_for_delalloc(struct inode *inode,
1556                                            struct page *locked_page,
1557                                            u64 start, u64 end)
1558 {
1559         int ret;
1560         struct page *pages[16];
1561         unsigned long index = start >> PAGE_CACHE_SHIFT;
1562         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1563         unsigned long nr_pages = end_index - index + 1;
1564         int i;
1565
1566         if (index == locked_page->index && end_index == index)
1567                 return;
1568
1569         while (nr_pages > 0) {
1570                 ret = find_get_pages_contig(inode->i_mapping, index,
1571                                      min_t(unsigned long, nr_pages,
1572                                      ARRAY_SIZE(pages)), pages);
1573                 for (i = 0; i < ret; i++) {
1574                         if (pages[i] != locked_page)
1575                                 unlock_page(pages[i]);
1576                         page_cache_release(pages[i]);
1577                 }
1578                 nr_pages -= ret;
1579                 index += ret;
1580                 cond_resched();
1581         }
1582 }
1583
1584 static noinline int lock_delalloc_pages(struct inode *inode,
1585                                         struct page *locked_page,
1586                                         u64 delalloc_start,
1587                                         u64 delalloc_end)
1588 {
1589         unsigned long index = delalloc_start >> PAGE_CACHE_SHIFT;
1590         unsigned long start_index = index;
1591         unsigned long end_index = delalloc_end >> PAGE_CACHE_SHIFT;
1592         unsigned long pages_locked = 0;
1593         struct page *pages[16];
1594         unsigned long nrpages;
1595         int ret;
1596         int i;
1597
1598         /* the caller is responsible for locking the start index */
1599         if (index == locked_page->index && index == end_index)
1600                 return 0;
1601
1602         /* skip the page at the start index */
1603         nrpages = end_index - index + 1;
1604         while (nrpages > 0) {
1605                 ret = find_get_pages_contig(inode->i_mapping, index,
1606                                      min_t(unsigned long,
1607                                      nrpages, ARRAY_SIZE(pages)), pages);
1608                 if (ret == 0) {
1609                         ret = -EAGAIN;
1610                         goto done;
1611                 }
1612                 /* now we have an array of pages, lock them all */
1613                 for (i = 0; i < ret; i++) {
1614                         /*
1615                          * the caller is taking responsibility for
1616                          * locked_page
1617                          */
1618                         if (pages[i] != locked_page) {
1619                                 lock_page(pages[i]);
1620                                 if (!PageDirty(pages[i]) ||
1621                                     pages[i]->mapping != inode->i_mapping) {
1622                                         ret = -EAGAIN;
1623                                         unlock_page(pages[i]);
1624                                         page_cache_release(pages[i]);
1625                                         goto done;
1626                                 }
1627                         }
1628                         page_cache_release(pages[i]);
1629                         pages_locked++;
1630                 }
1631                 nrpages -= ret;
1632                 index += ret;
1633                 cond_resched();
1634         }
1635         ret = 0;
1636 done:
1637         if (ret && pages_locked) {
1638                 __unlock_for_delalloc(inode, locked_page,
1639                               delalloc_start,
1640                               ((u64)(start_index + pages_locked - 1)) <<
1641                               PAGE_CACHE_SHIFT);
1642         }
1643         return ret;
1644 }
1645
1646 /*
1647  * find a contiguous range of bytes in the file marked as delalloc, not
1648  * more than 'max_bytes'.  start and end are used to return the range,
1649  *
1650  * 1 is returned if we find something, 0 if nothing was in the tree
1651  */
1652 STATIC u64 find_lock_delalloc_range(struct inode *inode,
1653                                     struct extent_io_tree *tree,
1654                                     struct page *locked_page, u64 *start,
1655                                     u64 *end, u64 max_bytes)
1656 {
1657         u64 delalloc_start;
1658         u64 delalloc_end;
1659         u64 found;
1660         struct extent_state *cached_state = NULL;
1661         int ret;
1662         int loops = 0;
1663
1664 again:
1665         /* step one, find a bunch of delalloc bytes starting at start */
1666         delalloc_start = *start;
1667         delalloc_end = 0;
1668         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1669                                     max_bytes, &cached_state);
1670         if (!found || delalloc_end <= *start) {
1671                 *start = delalloc_start;
1672                 *end = delalloc_end;
1673                 free_extent_state(cached_state);
1674                 return 0;
1675         }
1676
1677         /*
1678          * start comes from the offset of locked_page.  We have to lock
1679          * pages in order, so we can't process delalloc bytes before
1680          * locked_page
1681          */
1682         if (delalloc_start < *start)
1683                 delalloc_start = *start;
1684
1685         /*
1686          * make sure to limit the number of pages we try to lock down
1687          */
1688         if (delalloc_end + 1 - delalloc_start > max_bytes)
1689                 delalloc_end = delalloc_start + max_bytes - 1;
1690
1691         /* step two, lock all the pages after the page that has start */
1692         ret = lock_delalloc_pages(inode, locked_page,
1693                                   delalloc_start, delalloc_end);
1694         if (ret == -EAGAIN) {
1695                 /* some of the pages are gone, lets avoid looping by
1696                  * shortening the size of the delalloc range we're searching
1697                  */
1698                 free_extent_state(cached_state);
1699                 cached_state = NULL;
1700                 if (!loops) {
1701                         max_bytes = PAGE_CACHE_SIZE;
1702                         loops = 1;
1703                         goto again;
1704                 } else {
1705                         found = 0;
1706                         goto out_failed;
1707                 }
1708         }
1709         BUG_ON(ret); /* Only valid values are 0 and -EAGAIN */
1710
1711         /* step three, lock the state bits for the whole range */
1712         lock_extent_bits(tree, delalloc_start, delalloc_end, 0, &cached_state);
1713
1714         /* then test to make sure it is all still delalloc */
1715         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1716                              EXTENT_DELALLOC, 1, cached_state);
1717         if (!ret) {
1718                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1719                                      &cached_state, GFP_NOFS);
1720                 __unlock_for_delalloc(inode, locked_page,
1721                               delalloc_start, delalloc_end);
1722                 cond_resched();
1723                 goto again;
1724         }
1725         free_extent_state(cached_state);
1726         *start = delalloc_start;
1727         *end = delalloc_end;
1728 out_failed:
1729         return found;
1730 }
1731
1732 int extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
1733                                  struct page *locked_page,
1734                                  unsigned long clear_bits,
1735                                  unsigned long page_ops)
1736 {
1737         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
1738         int ret;
1739         struct page *pages[16];
1740         unsigned long index = start >> PAGE_CACHE_SHIFT;
1741         unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1742         unsigned long nr_pages = end_index - index + 1;
1743         int i;
1744
1745         clear_extent_bit(tree, start, end, clear_bits, 1, 0, NULL, GFP_NOFS);
1746         if (page_ops == 0)
1747                 return 0;
1748
1749         while (nr_pages > 0) {
1750                 ret = find_get_pages_contig(inode->i_mapping, index,
1751                                      min_t(unsigned long,
1752                                      nr_pages, ARRAY_SIZE(pages)), pages);
1753                 for (i = 0; i < ret; i++) {
1754
1755                         if (page_ops & PAGE_SET_PRIVATE2)
1756                                 SetPagePrivate2(pages[i]);
1757
1758                         if (pages[i] == locked_page) {
1759                                 page_cache_release(pages[i]);
1760                                 continue;
1761                         }
1762                         if (page_ops & PAGE_CLEAR_DIRTY)
1763                                 clear_page_dirty_for_io(pages[i]);
1764                         if (page_ops & PAGE_SET_WRITEBACK)
1765                                 set_page_writeback(pages[i]);
1766                         if (page_ops & PAGE_END_WRITEBACK)
1767                                 end_page_writeback(pages[i]);
1768                         if (page_ops & PAGE_UNLOCK)
1769                                 unlock_page(pages[i]);
1770                         page_cache_release(pages[i]);
1771                 }
1772                 nr_pages -= ret;
1773                 index += ret;
1774                 cond_resched();
1775         }
1776         return 0;
1777 }
1778
1779 /*
1780  * count the number of bytes in the tree that have a given bit(s)
1781  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1782  * cached.  The total number found is returned.
1783  */
1784 u64 count_range_bits(struct extent_io_tree *tree,
1785                      u64 *start, u64 search_end, u64 max_bytes,
1786                      unsigned long bits, int contig)
1787 {
1788         struct rb_node *node;
1789         struct extent_state *state;
1790         u64 cur_start = *start;
1791         u64 total_bytes = 0;
1792         u64 last = 0;
1793         int found = 0;
1794
1795         if (WARN_ON(search_end <= cur_start))
1796                 return 0;
1797
1798         spin_lock(&tree->lock);
1799         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1800                 total_bytes = tree->dirty_bytes;
1801                 goto out;
1802         }
1803         /*
1804          * this search will find all the extents that end after
1805          * our range starts.
1806          */
1807         node = tree_search(tree, cur_start);
1808         if (!node)
1809                 goto out;
1810
1811         while (1) {
1812                 state = rb_entry(node, struct extent_state, rb_node);
1813                 if (state->start > search_end)
1814                         break;
1815                 if (contig && found && state->start > last + 1)
1816                         break;
1817                 if (state->end >= cur_start && (state->state & bits) == bits) {
1818                         total_bytes += min(search_end, state->end) + 1 -
1819                                        max(cur_start, state->start);
1820                         if (total_bytes >= max_bytes)
1821                                 break;
1822                         if (!found) {
1823                                 *start = max(cur_start, state->start);
1824                                 found = 1;
1825                         }
1826                         last = state->end;
1827                 } else if (contig && found) {
1828                         break;
1829                 }
1830                 node = rb_next(node);
1831                 if (!node)
1832                         break;
1833         }
1834 out:
1835         spin_unlock(&tree->lock);
1836         return total_bytes;
1837 }
1838
1839 /*
1840  * set the private field for a given byte offset in the tree.  If there isn't
1841  * an extent_state there already, this does nothing.
1842  */
1843 static int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
1844 {
1845         struct rb_node *node;
1846         struct extent_state *state;
1847         int ret = 0;
1848
1849         spin_lock(&tree->lock);
1850         /*
1851          * this search will find all the extents that end after
1852          * our range starts.
1853          */
1854         node = tree_search(tree, start);
1855         if (!node) {
1856                 ret = -ENOENT;
1857                 goto out;
1858         }
1859         state = rb_entry(node, struct extent_state, rb_node);
1860         if (state->start != start) {
1861                 ret = -ENOENT;
1862                 goto out;
1863         }
1864         state->private = private;
1865 out:
1866         spin_unlock(&tree->lock);
1867         return ret;
1868 }
1869
1870 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
1871 {
1872         struct rb_node *node;
1873         struct extent_state *state;
1874         int ret = 0;
1875
1876         spin_lock(&tree->lock);
1877         /*
1878          * this search will find all the extents that end after
1879          * our range starts.
1880          */
1881         node = tree_search(tree, start);
1882         if (!node) {
1883                 ret = -ENOENT;
1884                 goto out;
1885         }
1886         state = rb_entry(node, struct extent_state, rb_node);
1887         if (state->start != start) {
1888                 ret = -ENOENT;
1889                 goto out;
1890         }
1891         *private = state->private;
1892 out:
1893         spin_unlock(&tree->lock);
1894         return ret;
1895 }
1896
1897 /*
1898  * searches a range in the state tree for a given mask.
1899  * If 'filled' == 1, this returns 1 only if every extent in the tree
1900  * has the bits set.  Otherwise, 1 is returned if any bit in the
1901  * range is found set.
1902  */
1903 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1904                    unsigned long bits, int filled, struct extent_state *cached)
1905 {
1906         struct extent_state *state = NULL;
1907         struct rb_node *node;
1908         int bitset = 0;
1909
1910         spin_lock(&tree->lock);
1911         if (cached && extent_state_in_tree(cached) && cached->start <= start &&
1912             cached->end > start)
1913                 node = &cached->rb_node;
1914         else
1915                 node = tree_search(tree, start);
1916         while (node && start <= end) {
1917                 state = rb_entry(node, struct extent_state, rb_node);
1918
1919                 if (filled && state->start > start) {
1920                         bitset = 0;
1921                         break;
1922                 }
1923
1924                 if (state->start > end)
1925                         break;
1926
1927                 if (state->state & bits) {
1928                         bitset = 1;
1929                         if (!filled)
1930                                 break;
1931                 } else if (filled) {
1932                         bitset = 0;
1933                         break;
1934                 }
1935
1936                 if (state->end == (u64)-1)
1937                         break;
1938
1939                 start = state->end + 1;
1940                 if (start > end)
1941                         break;
1942                 node = rb_next(node);
1943                 if (!node) {
1944                         if (filled)
1945                                 bitset = 0;
1946                         break;
1947                 }
1948         }
1949         spin_unlock(&tree->lock);
1950         return bitset;
1951 }
1952
1953 /*
1954  * helper function to set a given page up to date if all the
1955  * extents in the tree for that page are up to date
1956  */
1957 static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
1958 {
1959         u64 start = page_offset(page);
1960         u64 end = start + PAGE_CACHE_SIZE - 1;
1961         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
1962                 SetPageUptodate(page);
1963 }
1964
1965 int free_io_failure(struct inode *inode, struct io_failure_record *rec)
1966 {
1967         int ret;
1968         int err = 0;
1969         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
1970
1971         set_state_private(failure_tree, rec->start, 0);
1972         ret = clear_extent_bits(failure_tree, rec->start,
1973                                 rec->start + rec->len - 1,
1974                                 EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
1975         if (ret)
1976                 err = ret;
1977
1978         ret = clear_extent_bits(&BTRFS_I(inode)->io_tree, rec->start,
1979                                 rec->start + rec->len - 1,
1980                                 EXTENT_DAMAGED, GFP_NOFS);
1981         if (ret && !err)
1982                 err = ret;
1983
1984         kfree(rec);
1985         return err;
1986 }
1987
1988 /*
1989  * this bypasses the standard btrfs submit functions deliberately, as
1990  * the standard behavior is to write all copies in a raid setup. here we only
1991  * want to write the one bad copy. so we do the mapping for ourselves and issue
1992  * submit_bio directly.
1993  * to avoid any synchronization issues, wait for the data after writing, which
1994  * actually prevents the read that triggered the error from finishing.
1995  * currently, there can be no more than two copies of every data bit. thus,
1996  * exactly one rewrite is required.
1997  */
1998 int repair_io_failure(struct inode *inode, u64 start, u64 length, u64 logical,
1999                       struct page *page, unsigned int pg_offset, int mirror_num)
2000 {
2001         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2002         struct bio *bio;
2003         struct btrfs_device *dev;
2004         u64 map_length = 0;
2005         u64 sector;
2006         struct btrfs_bio *bbio = NULL;
2007         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
2008         int ret;
2009
2010         ASSERT(!(fs_info->sb->s_flags & MS_RDONLY));
2011         BUG_ON(!mirror_num);
2012
2013         /* we can't repair anything in raid56 yet */
2014         if (btrfs_is_parity_mirror(map_tree, logical, length, mirror_num))
2015                 return 0;
2016
2017         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2018         if (!bio)
2019                 return -EIO;
2020         bio->bi_iter.bi_size = 0;
2021         map_length = length;
2022
2023         ret = btrfs_map_block(fs_info, WRITE, logical,
2024                               &map_length, &bbio, mirror_num);
2025         if (ret) {
2026                 bio_put(bio);
2027                 return -EIO;
2028         }
2029         BUG_ON(mirror_num != bbio->mirror_num);
2030         sector = bbio->stripes[mirror_num-1].physical >> 9;
2031         bio->bi_iter.bi_sector = sector;
2032         dev = bbio->stripes[mirror_num-1].dev;
2033         kfree(bbio);
2034         if (!dev || !dev->bdev || !dev->writeable) {
2035                 bio_put(bio);
2036                 return -EIO;
2037         }
2038         bio->bi_bdev = dev->bdev;
2039         bio_add_page(bio, page, length, pg_offset);
2040
2041         if (btrfsic_submit_bio_wait(WRITE_SYNC, bio)) {
2042                 /* try to remap that extent elsewhere? */
2043                 bio_put(bio);
2044                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
2045                 return -EIO;
2046         }
2047
2048         printk_ratelimited_in_rcu(KERN_INFO
2049                                   "BTRFS: read error corrected: ino %llu off %llu (dev %s sector %llu)\n",
2050                                   btrfs_ino(inode), start,
2051                                   rcu_str_deref(dev->name), sector);
2052         bio_put(bio);
2053         return 0;
2054 }
2055
2056 int repair_eb_io_failure(struct btrfs_root *root, struct extent_buffer *eb,
2057                          int mirror_num)
2058 {
2059         u64 start = eb->start;
2060         unsigned long i, num_pages = num_extent_pages(eb->start, eb->len);
2061         int ret = 0;
2062
2063         if (root->fs_info->sb->s_flags & MS_RDONLY)
2064                 return -EROFS;
2065
2066         for (i = 0; i < num_pages; i++) {
2067                 struct page *p = eb->pages[i];
2068
2069                 ret = repair_io_failure(root->fs_info->btree_inode, start,
2070                                         PAGE_CACHE_SIZE, start, p,
2071                                         start - page_offset(p), mirror_num);
2072                 if (ret)
2073                         break;
2074                 start += PAGE_CACHE_SIZE;
2075         }
2076
2077         return ret;
2078 }
2079
2080 /*
2081  * each time an IO finishes, we do a fast check in the IO failure tree
2082  * to see if we need to process or clean up an io_failure_record
2083  */
2084 int clean_io_failure(struct inode *inode, u64 start, struct page *page,
2085                      unsigned int pg_offset)
2086 {
2087         u64 private;
2088         u64 private_failure;
2089         struct io_failure_record *failrec;
2090         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2091         struct extent_state *state;
2092         int num_copies;
2093         int ret;
2094
2095         private = 0;
2096         ret = count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
2097                                 (u64)-1, 1, EXTENT_DIRTY, 0);
2098         if (!ret)
2099                 return 0;
2100
2101         ret = get_state_private(&BTRFS_I(inode)->io_failure_tree, start,
2102                                 &private_failure);
2103         if (ret)
2104                 return 0;
2105
2106         failrec = (struct io_failure_record *)(unsigned long) private_failure;
2107         BUG_ON(!failrec->this_mirror);
2108
2109         if (failrec->in_validation) {
2110                 /* there was no real error, just free the record */
2111                 pr_debug("clean_io_failure: freeing dummy error at %llu\n",
2112                          failrec->start);
2113                 goto out;
2114         }
2115         if (fs_info->sb->s_flags & MS_RDONLY)
2116                 goto out;
2117
2118         spin_lock(&BTRFS_I(inode)->io_tree.lock);
2119         state = find_first_extent_bit_state(&BTRFS_I(inode)->io_tree,
2120                                             failrec->start,
2121                                             EXTENT_LOCKED);
2122         spin_unlock(&BTRFS_I(inode)->io_tree.lock);
2123
2124         if (state && state->start <= failrec->start &&
2125             state->end >= failrec->start + failrec->len - 1) {
2126                 num_copies = btrfs_num_copies(fs_info, failrec->logical,
2127                                               failrec->len);
2128                 if (num_copies > 1)  {
2129                         repair_io_failure(inode, start, failrec->len,
2130                                           failrec->logical, page,
2131                                           pg_offset, failrec->failed_mirror);
2132                 }
2133         }
2134
2135 out:
2136         free_io_failure(inode, failrec);
2137
2138         return 0;
2139 }
2140
2141 /*
2142  * Can be called when
2143  * - hold extent lock
2144  * - under ordered extent
2145  * - the inode is freeing
2146  */
2147 void btrfs_free_io_failure_record(struct inode *inode, u64 start, u64 end)
2148 {
2149         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2150         struct io_failure_record *failrec;
2151         struct extent_state *state, *next;
2152
2153         if (RB_EMPTY_ROOT(&failure_tree->state))
2154                 return;
2155
2156         spin_lock(&failure_tree->lock);
2157         state = find_first_extent_bit_state(failure_tree, start, EXTENT_DIRTY);
2158         while (state) {
2159                 if (state->start > end)
2160                         break;
2161
2162                 ASSERT(state->end <= end);
2163
2164                 next = next_state(state);
2165
2166                 failrec = (struct io_failure_record *)state->private;
2167                 free_extent_state(state);
2168                 kfree(failrec);
2169
2170                 state = next;
2171         }
2172         spin_unlock(&failure_tree->lock);
2173 }
2174
2175 int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
2176                                 struct io_failure_record **failrec_ret)
2177 {
2178         struct io_failure_record *failrec;
2179         u64 private;
2180         struct extent_map *em;
2181         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2182         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2183         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2184         int ret;
2185         u64 logical;
2186
2187         ret = get_state_private(failure_tree, start, &private);
2188         if (ret) {
2189                 failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
2190                 if (!failrec)
2191                         return -ENOMEM;
2192
2193                 failrec->start = start;
2194                 failrec->len = end - start + 1;
2195                 failrec->this_mirror = 0;
2196                 failrec->bio_flags = 0;
2197                 failrec->in_validation = 0;
2198
2199                 read_lock(&em_tree->lock);
2200                 em = lookup_extent_mapping(em_tree, start, failrec->len);
2201                 if (!em) {
2202                         read_unlock(&em_tree->lock);
2203                         kfree(failrec);
2204                         return -EIO;
2205                 }
2206
2207                 if (em->start > start || em->start + em->len <= start) {
2208                         free_extent_map(em);
2209                         em = NULL;
2210                 }
2211                 read_unlock(&em_tree->lock);
2212                 if (!em) {
2213                         kfree(failrec);
2214                         return -EIO;
2215                 }
2216
2217                 logical = start - em->start;
2218                 logical = em->block_start + logical;
2219                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2220                         logical = em->block_start;
2221                         failrec->bio_flags = EXTENT_BIO_COMPRESSED;
2222                         extent_set_compress_type(&failrec->bio_flags,
2223                                                  em->compress_type);
2224                 }
2225
2226                 pr_debug("Get IO Failure Record: (new) logical=%llu, start=%llu, len=%llu\n",
2227                          logical, start, failrec->len);
2228
2229                 failrec->logical = logical;
2230                 free_extent_map(em);
2231
2232                 /* set the bits in the private failure tree */
2233                 ret = set_extent_bits(failure_tree, start, end,
2234                                         EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
2235                 if (ret >= 0)
2236                         ret = set_state_private(failure_tree, start,
2237                                                 (u64)(unsigned long)failrec);
2238                 /* set the bits in the inode's tree */
2239                 if (ret >= 0)
2240                         ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED,
2241                                                 GFP_NOFS);
2242                 if (ret < 0) {
2243                         kfree(failrec);
2244                         return ret;
2245                 }
2246         } else {
2247                 failrec = (struct io_failure_record *)(unsigned long)private;
2248                 pr_debug("Get IO Failure Record: (found) logical=%llu, start=%llu, len=%llu, validation=%d\n",
2249                          failrec->logical, failrec->start, failrec->len,
2250                          failrec->in_validation);
2251                 /*
2252                  * when data can be on disk more than twice, add to failrec here
2253                  * (e.g. with a list for failed_mirror) to make
2254                  * clean_io_failure() clean all those errors at once.
2255                  */
2256         }
2257
2258         *failrec_ret = failrec;
2259
2260         return 0;
2261 }
2262
2263 int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
2264                            struct io_failure_record *failrec, int failed_mirror)
2265 {
2266         int num_copies;
2267
2268         num_copies = btrfs_num_copies(BTRFS_I(inode)->root->fs_info,
2269                                       failrec->logical, failrec->len);
2270         if (num_copies == 1) {
2271                 /*
2272                  * we only have a single copy of the data, so don't bother with
2273                  * all the retry and error correction code that follows. no
2274                  * matter what the error is, it is very likely to persist.
2275                  */
2276                 pr_debug("Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d\n",
2277                          num_copies, failrec->this_mirror, failed_mirror);
2278                 return 0;
2279         }
2280
2281         /*
2282          * there are two premises:
2283          *      a) deliver good data to the caller
2284          *      b) correct the bad sectors on disk
2285          */
2286         if (failed_bio->bi_vcnt > 1) {
2287                 /*
2288                  * to fulfill b), we need to know the exact failing sectors, as
2289                  * we don't want to rewrite any more than the failed ones. thus,
2290                  * we need separate read requests for the failed bio
2291                  *
2292                  * if the following BUG_ON triggers, our validation request got
2293                  * merged. we need separate requests for our algorithm to work.
2294                  */
2295                 BUG_ON(failrec->in_validation);
2296                 failrec->in_validation = 1;
2297                 failrec->this_mirror = failed_mirror;
2298         } else {
2299                 /*
2300                  * we're ready to fulfill a) and b) alongside. get a good copy
2301                  * of the failed sector and if we succeed, we have setup
2302                  * everything for repair_io_failure to do the rest for us.
2303                  */
2304                 if (failrec->in_validation) {
2305                         BUG_ON(failrec->this_mirror != failed_mirror);
2306                         failrec->in_validation = 0;
2307                         failrec->this_mirror = 0;
2308                 }
2309                 failrec->failed_mirror = failed_mirror;
2310                 failrec->this_mirror++;
2311                 if (failrec->this_mirror == failed_mirror)
2312                         failrec->this_mirror++;
2313         }
2314
2315         if (failrec->this_mirror > num_copies) {
2316                 pr_debug("Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d\n",
2317                          num_copies, failrec->this_mirror, failed_mirror);
2318                 return 0;
2319         }
2320
2321         return 1;
2322 }
2323
2324
2325 struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
2326                                     struct io_failure_record *failrec,
2327                                     struct page *page, int pg_offset, int icsum,
2328                                     bio_end_io_t *endio_func, void *data)
2329 {
2330         struct bio *bio;
2331         struct btrfs_io_bio *btrfs_failed_bio;
2332         struct btrfs_io_bio *btrfs_bio;
2333
2334         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2335         if (!bio)
2336                 return NULL;
2337
2338         bio->bi_end_io = endio_func;
2339         bio->bi_iter.bi_sector = failrec->logical >> 9;
2340         bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
2341         bio->bi_iter.bi_size = 0;
2342         bio->bi_private = data;
2343
2344         btrfs_failed_bio = btrfs_io_bio(failed_bio);
2345         if (btrfs_failed_bio->csum) {
2346                 struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2347                 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
2348
2349                 btrfs_bio = btrfs_io_bio(bio);
2350                 btrfs_bio->csum = btrfs_bio->csum_inline;
2351                 icsum *= csum_size;
2352                 memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + icsum,
2353                        csum_size);
2354         }
2355
2356         bio_add_page(bio, page, failrec->len, pg_offset);
2357
2358         return bio;
2359 }
2360
2361 /*
2362  * this is a generic handler for readpage errors (default
2363  * readpage_io_failed_hook). if other copies exist, read those and write back
2364  * good data to the failed position. does not investigate in remapping the
2365  * failed extent elsewhere, hoping the device will be smart enough to do this as
2366  * needed
2367  */
2368
2369 static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
2370                               struct page *page, u64 start, u64 end,
2371                               int failed_mirror)
2372 {
2373         struct io_failure_record *failrec;
2374         struct inode *inode = page->mapping->host;
2375         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2376         struct bio *bio;
2377         int read_mode;
2378         int ret;
2379
2380         BUG_ON(failed_bio->bi_rw & REQ_WRITE);
2381
2382         ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
2383         if (ret)
2384                 return ret;
2385
2386         ret = btrfs_check_repairable(inode, failed_bio, failrec, failed_mirror);
2387         if (!ret) {
2388                 free_io_failure(inode, failrec);
2389                 return -EIO;
2390         }
2391
2392         if (failed_bio->bi_vcnt > 1)
2393                 read_mode = READ_SYNC | REQ_FAILFAST_DEV;
2394         else
2395                 read_mode = READ_SYNC;
2396
2397         phy_offset >>= inode->i_sb->s_blocksize_bits;
2398         bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
2399                                       start - page_offset(page),
2400                                       (int)phy_offset, failed_bio->bi_end_io,
2401                                       NULL);
2402         if (!bio) {
2403                 free_io_failure(inode, failrec);
2404                 return -EIO;
2405         }
2406
2407         pr_debug("Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d\n",
2408                  read_mode, failrec->this_mirror, failrec->in_validation);
2409
2410         ret = tree->ops->submit_bio_hook(inode, read_mode, bio,
2411                                          failrec->this_mirror,
2412                                          failrec->bio_flags, 0);
2413         if (ret) {
2414                 free_io_failure(inode, failrec);
2415                 bio_put(bio);
2416         }
2417
2418         return ret;
2419 }
2420
2421 /* lots and lots of room for performance fixes in the end_bio funcs */
2422
2423 int end_extent_writepage(struct page *page, int err, u64 start, u64 end)
2424 {
2425         int uptodate = (err == 0);
2426         struct extent_io_tree *tree;
2427         int ret = 0;
2428
2429         tree = &BTRFS_I(page->mapping->host)->io_tree;
2430
2431         if (tree->ops && tree->ops->writepage_end_io_hook) {
2432                 ret = tree->ops->writepage_end_io_hook(page, start,
2433                                                end, NULL, uptodate);
2434                 if (ret)
2435                         uptodate = 0;
2436         }
2437
2438         if (!uptodate) {
2439                 ClearPageUptodate(page);
2440                 SetPageError(page);
2441                 ret = ret < 0 ? ret : -EIO;
2442                 mapping_set_error(page->mapping, ret);
2443         }
2444         return 0;
2445 }
2446
2447 /*
2448  * after a writepage IO is done, we need to:
2449  * clear the uptodate bits on error
2450  * clear the writeback bits in the extent tree for this IO
2451  * end_page_writeback if the page has no more pending IO
2452  *
2453  * Scheduling is not allowed, so the extent state tree is expected
2454  * to have one and only one object corresponding to this IO.
2455  */
2456 static void end_bio_extent_writepage(struct bio *bio, int err)
2457 {
2458         struct bio_vec *bvec;
2459         u64 start;
2460         u64 end;
2461         int i;
2462
2463         bio_for_each_segment_all(bvec, bio, i) {
2464                 struct page *page = bvec->bv_page;
2465
2466                 /* We always issue full-page reads, but if some block
2467                  * in a page fails to read, blk_update_request() will
2468                  * advance bv_offset and adjust bv_len to compensate.
2469                  * Print a warning for nonzero offsets, and an error
2470                  * if they don't add up to a full page.  */
2471                 if (bvec->bv_offset || bvec->bv_len != PAGE_CACHE_SIZE) {
2472                         if (bvec->bv_offset + bvec->bv_len != PAGE_CACHE_SIZE)
2473                                 btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2474                                    "partial page write in btrfs with offset %u and length %u",
2475                                         bvec->bv_offset, bvec->bv_len);
2476                         else
2477                                 btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2478                                    "incomplete page write in btrfs with offset %u and "
2479                                    "length %u",
2480                                         bvec->bv_offset, bvec->bv_len);
2481                 }
2482
2483                 start = page_offset(page);
2484                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2485
2486                 if (end_extent_writepage(page, err, start, end))
2487                         continue;
2488
2489                 end_page_writeback(page);
2490         }
2491
2492         bio_put(bio);
2493 }
2494
2495 static void
2496 endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
2497                               int uptodate)
2498 {
2499         struct extent_state *cached = NULL;
2500         u64 end = start + len - 1;
2501
2502         if (uptodate && tree->track_uptodate)
2503                 set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
2504         unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
2505 }
2506
2507 /*
2508  * after a readpage IO is done, we need to:
2509  * clear the uptodate bits on error
2510  * set the uptodate bits if things worked
2511  * set the page up to date if all extents in the tree are uptodate
2512  * clear the lock bit in the extent tree
2513  * unlock the page if there are no other extents locked for it
2514  *
2515  * Scheduling is not allowed, so the extent state tree is expected
2516  * to have one and only one object corresponding to this IO.
2517  */
2518 static void end_bio_extent_readpage(struct bio *bio, int err)
2519 {
2520         struct bio_vec *bvec;
2521         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
2522         struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
2523         struct extent_io_tree *tree;
2524         u64 offset = 0;
2525         u64 start;
2526         u64 end;
2527         u64 len;
2528         u64 extent_start = 0;
2529         u64 extent_len = 0;
2530         int mirror;
2531         int ret;
2532         int i;
2533
2534         if (err)
2535                 uptodate = 0;
2536
2537         bio_for_each_segment_all(bvec, bio, i) {
2538                 struct page *page = bvec->bv_page;
2539                 struct inode *inode = page->mapping->host;
2540
2541                 pr_debug("end_bio_extent_readpage: bi_sector=%llu, err=%d, "
2542                          "mirror=%u\n", (u64)bio->bi_iter.bi_sector, err,
2543                          io_bio->mirror_num);
2544                 tree = &BTRFS_I(inode)->io_tree;
2545
2546                 /* We always issue full-page reads, but if some block
2547                  * in a page fails to read, blk_update_request() will
2548                  * advance bv_offset and adjust bv_len to compensate.
2549                  * Print a warning for nonzero offsets, and an error
2550                  * if they don't add up to a full page.  */
2551                 if (bvec->bv_offset || bvec->bv_len != PAGE_CACHE_SIZE) {
2552                         if (bvec->bv_offset + bvec->bv_len != PAGE_CACHE_SIZE)
2553                                 btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2554                                    "partial page read in btrfs with offset %u and length %u",
2555                                         bvec->bv_offset, bvec->bv_len);
2556                         else
2557                                 btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2558                                    "incomplete page read in btrfs with offset %u and "
2559                                    "length %u",
2560                                         bvec->bv_offset, bvec->bv_len);
2561                 }
2562
2563                 start = page_offset(page);
2564                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2565                 len = bvec->bv_len;
2566
2567                 mirror = io_bio->mirror_num;
2568                 if (likely(uptodate && tree->ops &&
2569                            tree->ops->readpage_end_io_hook)) {
2570                         ret = tree->ops->readpage_end_io_hook(io_bio, offset,
2571                                                               page, start, end,
2572                                                               mirror);
2573                         if (ret)
2574                                 uptodate = 0;
2575                         else
2576                                 clean_io_failure(inode, start, page, 0);
2577                 }
2578
2579                 if (likely(uptodate))
2580                         goto readpage_ok;
2581
2582                 if (tree->ops && tree->ops->readpage_io_failed_hook) {
2583                         ret = tree->ops->readpage_io_failed_hook(page, mirror);
2584                         if (!ret && !err &&
2585                             test_bit(BIO_UPTODATE, &bio->bi_flags))
2586                                 uptodate = 1;
2587                 } else {
2588                         /*
2589                          * The generic bio_readpage_error handles errors the
2590                          * following way: If possible, new read requests are
2591                          * created and submitted and will end up in
2592                          * end_bio_extent_readpage as well (if we're lucky, not
2593                          * in the !uptodate case). In that case it returns 0 and
2594                          * we just go on with the next page in our bio. If it
2595                          * can't handle the error it will return -EIO and we
2596                          * remain responsible for that page.
2597                          */
2598                         ret = bio_readpage_error(bio, offset, page, start, end,
2599                                                  mirror);
2600                         if (ret == 0) {
2601                                 uptodate =
2602                                         test_bit(BIO_UPTODATE, &bio->bi_flags);
2603                                 if (err)
2604                                         uptodate = 0;
2605                                 offset += len;
2606                                 continue;
2607                         }
2608                 }
2609 readpage_ok:
2610                 if (likely(uptodate)) {
2611                         loff_t i_size = i_size_read(inode);
2612                         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2613                         unsigned off;
2614
2615                         /* Zero out the end if this page straddles i_size */
2616                         off = i_size & (PAGE_CACHE_SIZE-1);
2617                         if (page->index == end_index && off)
2618                                 zero_user_segment(page, off, PAGE_CACHE_SIZE);
2619                         SetPageUptodate(page);
2620                 } else {
2621                         ClearPageUptodate(page);
2622                         SetPageError(page);
2623                 }
2624                 unlock_page(page);
2625                 offset += len;
2626
2627                 if (unlikely(!uptodate)) {
2628                         if (extent_len) {
2629                                 endio_readpage_release_extent(tree,
2630                                                               extent_start,
2631                                                               extent_len, 1);
2632                                 extent_start = 0;
2633                                 extent_len = 0;
2634                         }
2635                         endio_readpage_release_extent(tree, start,
2636                                                       end - start + 1, 0);
2637                 } else if (!extent_len) {
2638                         extent_start = start;
2639                         extent_len = end + 1 - start;
2640                 } else if (extent_start + extent_len == start) {
2641                         extent_len += end + 1 - start;
2642                 } else {
2643                         endio_readpage_release_extent(tree, extent_start,
2644                                                       extent_len, uptodate);
2645                         extent_start = start;
2646                         extent_len = end + 1 - start;
2647                 }
2648         }
2649
2650         if (extent_len)
2651                 endio_readpage_release_extent(tree, extent_start, extent_len,
2652                                               uptodate);
2653         if (io_bio->end_io)
2654                 io_bio->end_io(io_bio, err);
2655         bio_put(bio);
2656 }
2657
2658 /*
2659  * this allocates from the btrfs_bioset.  We're returning a bio right now
2660  * but you can call btrfs_io_bio for the appropriate container_of magic
2661  */
2662 struct bio *
2663 btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
2664                 gfp_t gfp_flags)
2665 {
2666         struct btrfs_io_bio *btrfs_bio;
2667         struct bio *bio;
2668
2669         bio = bio_alloc_bioset(gfp_flags, nr_vecs, btrfs_bioset);
2670
2671         if (bio == NULL && (current->flags & PF_MEMALLOC)) {
2672                 while (!bio && (nr_vecs /= 2)) {
2673                         bio = bio_alloc_bioset(gfp_flags,
2674                                                nr_vecs, btrfs_bioset);
2675                 }
2676         }
2677
2678         if (bio) {
2679                 bio->bi_bdev = bdev;
2680                 bio->bi_iter.bi_sector = first_sector;
2681                 btrfs_bio = btrfs_io_bio(bio);
2682                 btrfs_bio->csum = NULL;
2683                 btrfs_bio->csum_allocated = NULL;
2684                 btrfs_bio->end_io = NULL;
2685         }
2686         return bio;
2687 }
2688
2689 struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
2690 {
2691         struct btrfs_io_bio *btrfs_bio;
2692         struct bio *new;
2693
2694         new = bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
2695         if (new) {
2696                 btrfs_bio = btrfs_io_bio(new);
2697                 btrfs_bio->csum = NULL;
2698                 btrfs_bio->csum_allocated = NULL;
2699                 btrfs_bio->end_io = NULL;
2700         }
2701         return new;
2702 }
2703
2704 /* this also allocates from the btrfs_bioset */
2705 struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
2706 {
2707         struct btrfs_io_bio *btrfs_bio;
2708         struct bio *bio;
2709
2710         bio = bio_alloc_bioset(gfp_mask, nr_iovecs, btrfs_bioset);
2711         if (bio) {
2712                 btrfs_bio = btrfs_io_bio(bio);
2713                 btrfs_bio->csum = NULL;
2714                 btrfs_bio->csum_allocated = NULL;
2715                 btrfs_bio->end_io = NULL;
2716         }
2717         return bio;
2718 }
2719
2720
2721 static int __must_check submit_one_bio(int rw, struct bio *bio,
2722                                        int mirror_num, unsigned long bio_flags)
2723 {
2724         int ret = 0;
2725         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
2726         struct page *page = bvec->bv_page;
2727         struct extent_io_tree *tree = bio->bi_private;
2728         u64 start;
2729
2730         start = page_offset(page) + bvec->bv_offset;
2731
2732         bio->bi_private = NULL;
2733
2734         bio_get(bio);
2735
2736         if (tree->ops && tree->ops->submit_bio_hook)
2737                 ret = tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
2738                                            mirror_num, bio_flags, start);
2739         else
2740                 btrfsic_submit_bio(rw, bio);
2741
2742         if (bio_flagged(bio, BIO_EOPNOTSUPP))
2743                 ret = -EOPNOTSUPP;
2744         bio_put(bio);
2745         return ret;
2746 }
2747
2748 static int merge_bio(int rw, struct extent_io_tree *tree, struct page *page,
2749                      unsigned long offset, size_t size, struct bio *bio,
2750                      unsigned long bio_flags)
2751 {
2752         int ret = 0;
2753         if (tree->ops && tree->ops->merge_bio_hook)
2754                 ret = tree->ops->merge_bio_hook(rw, page, offset, size, bio,
2755                                                 bio_flags);
2756         BUG_ON(ret < 0);
2757         return ret;
2758
2759 }
2760
2761 static int submit_extent_page(int rw, struct extent_io_tree *tree,
2762                               struct page *page, sector_t sector,
2763                               size_t size, unsigned long offset,
2764                               struct block_device *bdev,
2765                               struct bio **bio_ret,
2766                               unsigned long max_pages,
2767                               bio_end_io_t end_io_func,
2768                               int mirror_num,
2769                               unsigned long prev_bio_flags,
2770                               unsigned long bio_flags)
2771 {
2772         int ret = 0;
2773         struct bio *bio;
2774         int nr;
2775         int contig = 0;
2776         int this_compressed = bio_flags & EXTENT_BIO_COMPRESSED;
2777         int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
2778         size_t page_size = min_t(size_t, size, PAGE_CACHE_SIZE);
2779
2780         if (bio_ret && *bio_ret) {
2781                 bio = *bio_ret;
2782                 if (old_compressed)
2783                         contig = bio->bi_iter.bi_sector == sector;
2784                 else
2785                         contig = bio_end_sector(bio) == sector;
2786
2787                 if (prev_bio_flags != bio_flags || !contig ||
2788                     merge_bio(rw, tree, page, offset, page_size, bio, bio_flags) ||
2789                     bio_add_page(bio, page, page_size, offset) < page_size) {
2790                         ret = submit_one_bio(rw, bio, mirror_num,
2791                                              prev_bio_flags);
2792                         if (ret < 0)
2793                                 return ret;
2794                         bio = NULL;
2795                 } else {
2796                         return 0;
2797                 }
2798         }
2799         if (this_compressed)
2800                 nr = BIO_MAX_PAGES;
2801         else
2802                 nr = bio_get_nr_vecs(bdev);
2803
2804         bio = btrfs_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
2805         if (!bio)
2806                 return -ENOMEM;
2807
2808         bio_add_page(bio, page, page_size, offset);
2809         bio->bi_end_io = end_io_func;
2810         bio->bi_private = tree;
2811
2812         if (bio_ret)
2813                 *bio_ret = bio;
2814         else
2815                 ret = submit_one_bio(rw, bio, mirror_num, bio_flags);
2816
2817         return ret;
2818 }
2819
2820 static void attach_extent_buffer_page(struct extent_buffer *eb,
2821                                       struct page *page)
2822 {
2823         if (!PagePrivate(page)) {
2824                 SetPagePrivate(page);
2825                 page_cache_get(page);
2826                 set_page_private(page, (unsigned long)eb);
2827         } else {
2828                 WARN_ON(page->private != (unsigned long)eb);
2829         }
2830 }
2831
2832 void set_page_extent_mapped(struct page *page)
2833 {
2834         if (!PagePrivate(page)) {
2835                 SetPagePrivate(page);
2836                 page_cache_get(page);
2837                 set_page_private(page, EXTENT_PAGE_PRIVATE);
2838         }
2839 }
2840
2841 static struct extent_map *
2842 __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
2843                  u64 start, u64 len, get_extent_t *get_extent,
2844                  struct extent_map **em_cached)
2845 {
2846         struct extent_map *em;
2847
2848         if (em_cached && *em_cached) {
2849                 em = *em_cached;
2850                 if (extent_map_in_tree(em) && start >= em->start &&
2851                     start < extent_map_end(em)) {
2852                         atomic_inc(&em->refs);
2853                         return em;
2854                 }
2855
2856                 free_extent_map(em);
2857                 *em_cached = NULL;
2858         }
2859
2860         em = get_extent(inode, page, pg_offset, start, len, 0);
2861         if (em_cached && !IS_ERR_OR_NULL(em)) {
2862                 BUG_ON(*em_cached);
2863                 atomic_inc(&em->refs);
2864                 *em_cached = em;
2865         }
2866         return em;
2867 }
2868 /*
2869  * basic readpage implementation.  Locked extent state structs are inserted
2870  * into the tree that are removed when the IO is done (by the end_io
2871  * handlers)
2872  * XXX JDM: This needs looking at to ensure proper page locking
2873  */
2874 static int __do_readpage(struct extent_io_tree *tree,
2875                          struct page *page,
2876                          get_extent_t *get_extent,
2877                          struct extent_map **em_cached,
2878                          struct bio **bio, int mirror_num,
2879                          unsigned long *bio_flags, int rw)
2880 {
2881         struct inode *inode = page->mapping->host;
2882         u64 start = page_offset(page);
2883         u64 page_end = start + PAGE_CACHE_SIZE - 1;
2884         u64 end;
2885         u64 cur = start;
2886         u64 extent_offset;
2887         u64 last_byte = i_size_read(inode);
2888         u64 block_start;
2889         u64 cur_end;
2890         sector_t sector;
2891         struct extent_map *em;
2892         struct block_device *bdev;
2893         int ret;
2894         int nr = 0;
2895         int parent_locked = *bio_flags & EXTENT_BIO_PARENT_LOCKED;
2896         size_t pg_offset = 0;
2897         size_t iosize;
2898         size_t disk_io_size;
2899         size_t blocksize = inode->i_sb->s_blocksize;
2900         unsigned long this_bio_flag = *bio_flags & EXTENT_BIO_PARENT_LOCKED;
2901
2902         set_page_extent_mapped(page);
2903
2904         end = page_end;
2905         if (!PageUptodate(page)) {
2906                 if (cleancache_get_page(page) == 0) {
2907                         BUG_ON(blocksize != PAGE_SIZE);
2908                         unlock_extent(tree, start, end);
2909                         goto out;
2910                 }
2911         }
2912
2913         if (page->index == last_byte >> PAGE_CACHE_SHIFT) {
2914                 char *userpage;
2915                 size_t zero_offset = last_byte & (PAGE_CACHE_SIZE - 1);
2916
2917                 if (zero_offset) {
2918                         iosize = PAGE_CACHE_SIZE - zero_offset;
2919                         userpage = kmap_atomic(page);
2920                         memset(userpage + zero_offset, 0, iosize);
2921                         flush_dcache_page(page);
2922                         kunmap_atomic(userpage);
2923                 }
2924         }
2925         while (cur <= end) {
2926                 unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
2927
2928                 if (cur >= last_byte) {
2929                         char *userpage;
2930                         struct extent_state *cached = NULL;
2931
2932                         iosize = PAGE_CACHE_SIZE - pg_offset;
2933                         userpage = kmap_atomic(page);
2934                         memset(userpage + pg_offset, 0, iosize);
2935                         flush_dcache_page(page);
2936                         kunmap_atomic(userpage);
2937                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2938                                             &cached, GFP_NOFS);
2939                         if (!parent_locked)
2940                                 unlock_extent_cached(tree, cur,
2941                                                      cur + iosize - 1,
2942                                                      &cached, GFP_NOFS);
2943                         break;
2944                 }
2945                 em = __get_extent_map(inode, page, pg_offset, cur,
2946                                       end - cur + 1, get_extent, em_cached);
2947                 if (IS_ERR_OR_NULL(em)) {
2948                         SetPageError(page);
2949                         if (!parent_locked)
2950                                 unlock_extent(tree, cur, end);
2951                         break;
2952                 }
2953                 extent_offset = cur - em->start;
2954                 BUG_ON(extent_map_end(em) <= cur);
2955                 BUG_ON(end < cur);
2956
2957                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2958                         this_bio_flag |= EXTENT_BIO_COMPRESSED;
2959                         extent_set_compress_type(&this_bio_flag,
2960                                                  em->compress_type);
2961                 }
2962
2963                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2964                 cur_end = min(extent_map_end(em) - 1, end);
2965                 iosize = ALIGN(iosize, blocksize);
2966                 if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
2967                         disk_io_size = em->block_len;
2968                         sector = em->block_start >> 9;
2969                 } else {
2970                         sector = (em->block_start + extent_offset) >> 9;
2971                         disk_io_size = iosize;
2972                 }
2973                 bdev = em->bdev;
2974                 block_start = em->block_start;
2975                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2976                         block_start = EXTENT_MAP_HOLE;
2977                 free_extent_map(em);
2978                 em = NULL;
2979
2980                 /* we've found a hole, just zero and go on */
2981                 if (block_start == EXTENT_MAP_HOLE) {
2982                         char *userpage;
2983                         struct extent_state *cached = NULL;
2984
2985                         userpage = kmap_atomic(page);
2986                         memset(userpage + pg_offset, 0, iosize);
2987                         flush_dcache_page(page);
2988                         kunmap_atomic(userpage);
2989
2990                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2991                                             &cached, GFP_NOFS);
2992                         unlock_extent_cached(tree, cur, cur + iosize - 1,
2993                                              &cached, GFP_NOFS);
2994                         cur = cur + iosize;
2995                         pg_offset += iosize;
2996                         continue;
2997                 }
2998                 /* the get_extent function already copied into the page */
2999                 if (test_range_bit(tree, cur, cur_end,
3000                                    EXTENT_UPTODATE, 1, NULL)) {
3001                         check_page_uptodate(tree, page);
3002                         if (!parent_locked)
3003                                 unlock_extent(tree, cur, cur + iosize - 1);
3004                         cur = cur + iosize;
3005                         pg_offset += iosize;
3006                         continue;
3007                 }
3008                 /* we have an inline extent but it didn't get marked up
3009                  * to date.  Error out
3010                  */
3011                 if (block_start == EXTENT_MAP_INLINE) {
3012                         SetPageError(page);
3013                         if (!parent_locked)
3014                                 unlock_extent(tree, cur, cur + iosize - 1);
3015                         cur = cur + iosize;
3016                         pg_offset += iosize;
3017                         continue;
3018                 }
3019
3020                 pnr -= page->index;
3021                 ret = submit_extent_page(rw, tree, page,
3022                                          sector, disk_io_size, pg_offset,
3023                                          bdev, bio, pnr,
3024                                          end_bio_extent_readpage, mirror_num,
3025                                          *bio_flags,
3026                                          this_bio_flag);
3027                 if (!ret) {
3028                         nr++;
3029                         *bio_flags = this_bio_flag;
3030                 } else {
3031                         SetPageError(page);
3032                         if (!parent_locked)
3033                                 unlock_extent(tree, cur, cur + iosize - 1);
3034                 }
3035                 cur = cur + iosize;
3036                 pg_offset += iosize;
3037         }
3038 out:
3039         if (!nr) {
3040                 if (!PageError(page))
3041                         SetPageUptodate(page);
3042                 unlock_page(page);
3043         }
3044         return 0;
3045 }
3046
3047 static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
3048                                              struct page *pages[], int nr_pages,
3049                                              u64 start, u64 end,
3050                                              get_extent_t *get_extent,
3051                                              struct extent_map **em_cached,
3052                                              struct bio **bio, int mirror_num,
3053                                              unsigned long *bio_flags, int rw)
3054 {
3055         struct inode *inode;
3056         struct btrfs_ordered_extent *ordered;
3057         int index;
3058
3059         inode = pages[0]->mapping->host;
3060         while (1) {
3061                 lock_extent(tree, start, end);
3062                 ordered = btrfs_lookup_ordered_range(inode, start,
3063                                                      end - start + 1);
3064                 if (!ordered)
3065                         break;
3066                 unlock_extent(tree, start, end);
3067                 btrfs_start_ordered_extent(inode, ordered, 1);
3068                 btrfs_put_ordered_extent(ordered);
3069         }
3070
3071         for (index = 0; index < nr_pages; index++) {
3072                 __do_readpage(tree, pages[index], get_extent, em_cached, bio,
3073                               mirror_num, bio_flags, rw);
3074                 page_cache_release(pages[index]);
3075         }
3076 }
3077
3078 static void __extent_readpages(struct extent_io_tree *tree,
3079                                struct page *pages[],
3080                                int nr_pages, get_extent_t *get_extent,
3081                                struct extent_map **em_cached,
3082                                struct bio **bio, int mirror_num,
3083                                unsigned long *bio_flags, int rw)
3084 {
3085         u64 start = 0;
3086         u64 end = 0;
3087         u64 page_start;
3088         int index;
3089         int first_index = 0;
3090
3091         for (index = 0; index < nr_pages; index++) {
3092                 page_start = page_offset(pages[index]);
3093                 if (!end) {
3094                         start = page_start;
3095                         end = start + PAGE_CACHE_SIZE - 1;
3096                         first_index = index;
3097                 } else if (end + 1 == page_start) {
3098                         end += PAGE_CACHE_SIZE;
3099                 } else {
3100                         __do_contiguous_readpages(tree, &pages[first_index],
3101                                                   index - first_index, start,
3102                                                   end, get_extent, em_cached,
3103                                                   bio, mirror_num, bio_flags,
3104                                                   rw);
3105                         start = page_start;
3106                         end = start + PAGE_CACHE_SIZE - 1;
3107                         first_index = index;
3108                 }
3109         }
3110
3111         if (end)
3112                 __do_contiguous_readpages(tree, &pages[first_index],
3113                                           index - first_index, start,
3114                                           end, get_extent, em_cached, bio,
3115                                           mirror_num, bio_flags, rw);
3116 }
3117
3118 static int __extent_read_full_page(struct extent_io_tree *tree,
3119                                    struct page *page,
3120                                    get_extent_t *get_extent,
3121                                    struct bio **bio, int mirror_num,
3122                                    unsigned long *bio_flags, int rw)
3123 {
3124         struct inode *inode = page->mapping->host;
3125         struct btrfs_ordered_extent *ordered;
3126         u64 start = page_offset(page);
3127         u64 end = start + PAGE_CACHE_SIZE - 1;
3128         int ret;
3129
3130         while (1) {
3131                 lock_extent(tree, start, end);
3132                 ordered = btrfs_lookup_ordered_extent(inode, start);
3133                 if (!ordered)
3134                         break;
3135                 unlock_extent(tree, start, end);
3136                 btrfs_start_ordered_extent(inode, ordered, 1);
3137                 btrfs_put_ordered_extent(ordered);
3138         }
3139
3140         ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
3141                             bio_flags, rw);
3142         return ret;
3143 }
3144
3145 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
3146                             get_extent_t *get_extent, int mirror_num)
3147 {
3148         struct bio *bio = NULL;
3149         unsigned long bio_flags = 0;
3150         int ret;
3151
3152         ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
3153                                       &bio_flags, READ);
3154         if (bio)
3155                 ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
3156         return ret;
3157 }
3158
3159 int extent_read_full_page_nolock(struct extent_io_tree *tree, struct page *page,
3160                                  get_extent_t *get_extent, int mirror_num)
3161 {
3162         struct bio *bio = NULL;
3163         unsigned long bio_flags = EXTENT_BIO_PARENT_LOCKED;
3164         int ret;
3165
3166         ret = __do_readpage(tree, page, get_extent, NULL, &bio, mirror_num,
3167                                       &bio_flags, READ);
3168         if (bio)
3169                 ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
3170         return ret;
3171 }
3172
3173 static noinline void update_nr_written(struct page *page,
3174                                       struct writeback_control *wbc,
3175                                       unsigned long nr_written)
3176 {
3177         wbc->nr_to_write -= nr_written;
3178         if (wbc->range_cyclic || (wbc->nr_to_write > 0 &&
3179             wbc->range_start == 0 && wbc->range_end == LLONG_MAX))
3180                 page->mapping->writeback_index = page->index + nr_written;
3181 }
3182
3183 /*
3184  * helper for __extent_writepage, doing all of the delayed allocation setup.
3185  *
3186  * This returns 1 if our fill_delalloc function did all the work required
3187  * to write the page (copy into inline extent).  In this case the IO has
3188  * been started and the page is already unlocked.
3189  *
3190  * This returns 0 if all went well (page still locked)
3191  * This returns < 0 if there were errors (page still locked)
3192  */
3193 static noinline_for_stack int writepage_delalloc(struct inode *inode,
3194                               struct page *page, struct writeback_control *wbc,
3195                               struct extent_page_data *epd,
3196                               u64 delalloc_start,
3197                               unsigned long *nr_written)
3198 {
3199         struct extent_io_tree *tree = epd->tree;
3200         u64 page_end = delalloc_start + PAGE_CACHE_SIZE - 1;
3201         u64 nr_delalloc;
3202         u64 delalloc_to_write = 0;
3203         u64 delalloc_end = 0;
3204         int ret;
3205         int page_started = 0;
3206
3207         if (epd->extent_locked || !tree->ops || !tree->ops->fill_delalloc)
3208                 return 0;
3209
3210         while (delalloc_end < page_end) {
3211                 nr_delalloc = find_lock_delalloc_range(inode, tree,
3212                                                page,
3213                                                &delalloc_start,
3214                                                &delalloc_end,
3215                                                128 * 1024 * 1024);
3216                 if (nr_delalloc == 0) {
3217                         delalloc_start = delalloc_end + 1;
3218                         continue;
3219                 }
3220                 ret = tree->ops->fill_delalloc(inode, page,
3221                                                delalloc_start,
3222                                                delalloc_end,
3223                                                &page_started,
3224                                                nr_written);
3225                 /* File system has been set read-only */
3226                 if (ret) {
3227                         SetPageError(page);
3228                         /* fill_delalloc should be return < 0 for error
3229                          * but just in case, we use > 0 here meaning the
3230                          * IO is started, so we don't want to return > 0
3231                          * unless things are going well.
3232                          */
3233                         ret = ret < 0 ? ret : -EIO;
3234                         goto done;
3235                 }
3236                 /*
3237                  * delalloc_end is already one less than the total
3238                  * length, so we don't subtract one from
3239                  * PAGE_CACHE_SIZE
3240                  */
3241                 delalloc_to_write += (delalloc_end - delalloc_start +
3242                                       PAGE_CACHE_SIZE) >>
3243                                       PAGE_CACHE_SHIFT;
3244                 delalloc_start = delalloc_end + 1;
3245         }
3246         if (wbc->nr_to_write < delalloc_to_write) {
3247                 int thresh = 8192;
3248
3249                 if (delalloc_to_write < thresh * 2)
3250                         thresh = delalloc_to_write;
3251                 wbc->nr_to_write = min_t(u64, delalloc_to_write,
3252                                          thresh);
3253         }
3254
3255         /* did the fill delalloc function already unlock and start
3256          * the IO?
3257          */
3258         if (page_started) {
3259                 /*
3260                  * we've unlocked the page, so we can't update
3261                  * the mapping's writeback index, just update
3262                  * nr_to_write.
3263                  */
3264                 wbc->nr_to_write -= *nr_written;
3265                 return 1;
3266         }
3267
3268         ret = 0;
3269
3270 done:
3271         return ret;
3272 }
3273
3274 /*
3275  * helper for __extent_writepage.  This calls the writepage start hooks,
3276  * and does the loop to map the page into extents and bios.
3277  *
3278  * We return 1 if the IO is started and the page is unlocked,
3279  * 0 if all went well (page still locked)
3280  * < 0 if there were errors (page still locked)
3281  */
3282 static noinline_for_stack int __extent_writepage_io(struct inode *inode,
3283                                  struct page *page,
3284                                  struct writeback_control *wbc,
3285                                  struct extent_page_data *epd,
3286                                  loff_t i_size,
3287                                  unsigned long nr_written,
3288                                  int write_flags, int *nr_ret)
3289 {
3290         struct extent_io_tree *tree = epd->tree;
3291         u64 start = page_offset(page);
3292         u64 page_end = start + PAGE_CACHE_SIZE - 1;
3293         u64 end;
3294         u64 cur = start;
3295         u64 extent_offset;
3296         u64 block_start;
3297         u64 iosize;
3298         sector_t sector;
3299         struct extent_state *cached_state = NULL;
3300         struct extent_map *em;
3301         struct block_device *bdev;
3302         size_t pg_offset = 0;
3303         size_t blocksize;
3304         int ret = 0;
3305         int nr = 0;
3306         bool compressed;
3307
3308         if (tree->ops && tree->ops->writepage_start_hook) {
3309                 ret = tree->ops->writepage_start_hook(page, start,
3310                                                       page_end);
3311                 if (ret) {
3312                         /* Fixup worker will requeue */
3313                         if (ret == -EBUSY)
3314                                 wbc->pages_skipped++;
3315                         else
3316                                 redirty_page_for_writepage(wbc, page);
3317
3318                         update_nr_written(page, wbc, nr_written);
3319                         unlock_page(page);
3320                         ret = 1;
3321                         goto done_unlocked;
3322                 }
3323         }
3324
3325         /*
3326          * we don't want to touch the inode after unlocking the page,
3327          * so we update the mapping writeback index now
3328          */
3329         update_nr_written(page, wbc, nr_written + 1);
3330
3331         end = page_end;
3332         if (i_size <= start) {
3333                 if (tree->ops && tree->ops->writepage_end_io_hook)
3334                         tree->ops->writepage_end_io_hook(page, start,
3335                                                          page_end, NULL, 1);
3336                 goto done;
3337         }
3338
3339         blocksize = inode->i_sb->s_blocksize;
3340
3341         while (cur <= end) {
3342                 u64 em_end;
3343                 if (cur >= i_size) {
3344                         if (tree->ops && tree->ops->writepage_end_io_hook)
3345                                 tree->ops->writepage_end_io_hook(page, cur,
3346                                                          page_end, NULL, 1);
3347                         break;
3348                 }
3349                 em = epd->get_extent(inode, page, pg_offset, cur,
3350                                      end - cur + 1, 1);
3351                 if (IS_ERR_OR_NULL(em)) {
3352                         SetPageError(page);
3353                         ret = PTR_ERR_OR_ZERO(em);
3354                         break;
3355                 }
3356
3357                 extent_offset = cur - em->start;
3358                 em_end = extent_map_end(em);
3359                 BUG_ON(em_end <= cur);
3360                 BUG_ON(end < cur);
3361                 iosize = min(em_end - cur, end - cur + 1);
3362                 iosize = ALIGN(iosize, blocksize);
3363                 sector = (em->block_start + extent_offset) >> 9;
3364                 bdev = em->bdev;
3365                 block_start = em->block_start;
3366                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
3367                 free_extent_map(em);
3368                 em = NULL;
3369
3370                 /*
3371                  * compressed and inline extents are written through other
3372                  * paths in the FS
3373                  */
3374                 if (compressed || block_start == EXTENT_MAP_HOLE ||
3375                     block_start == EXTENT_MAP_INLINE) {
3376                         /*
3377                          * end_io notification does not happen here for
3378                          * compressed extents
3379                          */
3380                         if (!compressed && tree->ops &&
3381                             tree->ops->writepage_end_io_hook)
3382                                 tree->ops->writepage_end_io_hook(page, cur,
3383                                                          cur + iosize - 1,
3384                                                          NULL, 1);
3385                         else if (compressed) {
3386                                 /* we don't want to end_page_writeback on
3387                                  * a compressed extent.  this happens
3388                                  * elsewhere
3389                                  */
3390                                 nr++;
3391                         }
3392
3393                         cur += iosize;
3394                         pg_offset += iosize;
3395                         continue;
3396                 }
3397
3398                 if (tree->ops && tree->ops->writepage_io_hook) {
3399                         ret = tree->ops->writepage_io_hook(page, cur,
3400                                                 cur + iosize - 1);
3401                 } else {
3402                         ret = 0;
3403                 }
3404                 if (ret) {
3405                         SetPageError(page);
3406                 } else {
3407                         unsigned long max_nr = (i_size >> PAGE_CACHE_SHIFT) + 1;
3408
3409                         set_range_writeback(tree, cur, cur + iosize - 1);
3410                         if (!PageWriteback(page)) {
3411                                 btrfs_err(BTRFS_I(inode)->root->fs_info,
3412                                            "page %lu not writeback, cur %llu end %llu",
3413                                        page->index, cur, end);
3414                         }
3415
3416                         ret = submit_extent_page(write_flags, tree, page,
3417                                                  sector, iosize, pg_offset,
3418                                                  bdev, &epd->bio, max_nr,
3419                                                  end_bio_extent_writepage,
3420                                                  0, 0, 0);
3421                         if (ret)
3422                                 SetPageError(page);
3423                 }
3424                 cur = cur + iosize;
3425                 pg_offset += iosize;
3426                 nr++;
3427         }
3428 done:
3429         *nr_ret = nr;
3430
3431 done_unlocked:
3432
3433         /* drop our reference on any cached states */
3434         free_extent_state(cached_state);
3435         return ret;
3436 }
3437
3438 /*
3439  * the writepage semantics are similar to regular writepage.  extent
3440  * records are inserted to lock ranges in the tree, and as dirty areas
3441  * are found, they are marked writeback.  Then the lock bits are removed
3442  * and the end_io handler clears the writeback ranges
3443  */
3444 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
3445                               void *data)
3446 {
3447         struct inode *inode = page->mapping->host;
3448         struct extent_page_data *epd = data;
3449         u64 start = page_offset(page);
3450         u64 page_end = start + PAGE_CACHE_SIZE - 1;
3451         int ret;
3452         int nr = 0;
3453         size_t pg_offset = 0;
3454         loff_t i_size = i_size_read(inode);
3455         unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
3456         int write_flags;
3457         unsigned long nr_written = 0;
3458
3459         if (wbc->sync_mode == WB_SYNC_ALL)
3460                 write_flags = WRITE_SYNC;
3461         else
3462                 write_flags = WRITE;
3463
3464         trace___extent_writepage(page, inode, wbc);
3465
3466         WARN_ON(!PageLocked(page));
3467
3468         ClearPageError(page);
3469
3470         pg_offset = i_size & (PAGE_CACHE_SIZE - 1);
3471         if (page->index > end_index ||
3472            (page->index == end_index && !pg_offset)) {
3473                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_CACHE_SIZE);
3474                 unlock_page(page);
3475                 return 0;
3476         }
3477
3478         if (page->index == end_index) {
3479                 char *userpage;
3480
3481                 userpage = kmap_atomic(page);
3482                 memset(userpage + pg_offset, 0,
3483                        PAGE_CACHE_SIZE - pg_offset);
3484                 kunmap_atomic(userpage);
3485                 flush_dcache_page(page);
3486         }
3487
3488         pg_offset = 0;
3489
3490         set_page_extent_mapped(page);
3491
3492         ret = writepage_delalloc(inode, page, wbc, epd, start, &nr_written);
3493         if (ret == 1)
3494                 goto done_unlocked;
3495         if (ret)
3496                 goto done;
3497
3498         ret = __extent_writepage_io(inode, page, wbc, epd,
3499                                     i_size, nr_written, write_flags, &nr);
3500         if (ret == 1)
3501                 goto done_unlocked;
3502
3503 done:
3504         if (nr == 0) {
3505                 /* make sure the mapping tag for page dirty gets cleared */
3506                 set_page_writeback(page);
3507                 end_page_writeback(page);
3508         }
3509         if (PageError(page)) {
3510                 ret = ret < 0 ? ret : -EIO;
3511                 end_extent_writepage(page, ret, start, page_end);
3512         }
3513         unlock_page(page);
3514         return ret;
3515
3516 done_unlocked:
3517         return 0;
3518 }
3519
3520 void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
3521 {
3522         wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
3523                        TASK_UNINTERRUPTIBLE);
3524 }
3525
3526 static noinline_for_stack int
3527 lock_extent_buffer_for_io(struct extent_buffer *eb,
3528                           struct btrfs_fs_info *fs_info,
3529                           struct extent_page_data *epd)
3530 {
3531         unsigned long i, num_pages;
3532         int flush = 0;
3533         int ret = 0;
3534
3535         if (!btrfs_try_tree_write_lock(eb)) {
3536                 flush = 1;
3537                 flush_write_bio(epd);
3538                 btrfs_tree_lock(eb);
3539         }
3540
3541         if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
3542                 btrfs_tree_unlock(eb);
3543                 if (!epd->sync_io)
3544                         return 0;
3545                 if (!flush) {
3546                         flush_write_bio(epd);
3547                         flush = 1;
3548                 }
3549                 while (1) {
3550                         wait_on_extent_buffer_writeback(eb);
3551                         btrfs_tree_lock(eb);
3552                         if (!test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags))
3553                                 break;
3554                         btrfs_tree_unlock(eb);
3555                 }
3556         }
3557
3558         /*
3559          * We need to do this to prevent races in people who check if the eb is
3560          * under IO since we can end up having no IO bits set for a short period
3561          * of time.
3562          */
3563         spin_lock(&eb->refs_lock);
3564         if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3565                 set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3566                 spin_unlock(&eb->refs_lock);
3567                 btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
3568                 __percpu_counter_add(&fs_info->dirty_metadata_bytes,
3569                                      -eb->len,
3570                                      fs_info->dirty_metadata_batch);
3571                 ret = 1;
3572         } else {
3573                 spin_unlock(&eb->refs_lock);
3574         }
3575
3576         btrfs_tree_unlock(eb);
3577
3578         if (!ret)
3579                 return ret;
3580
3581         num_pages = num_extent_pages(eb->start, eb->len);
3582         for (i = 0; i < num_pages; i++) {
3583                 struct page *p = eb->pages[i];
3584
3585                 if (!trylock_page(p)) {
3586                         if (!flush) {
3587                                 flush_write_bio(epd);
3588                                 flush = 1;
3589                         }
3590                         lock_page(p);
3591                 }
3592         }
3593
3594         return ret;
3595 }
3596
3597 static void end_extent_buffer_writeback(struct extent_buffer *eb)
3598 {
3599         clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3600         smp_mb__after_atomic();
3601         wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
3602 }
3603
3604 static void set_btree_ioerr(struct page *page)
3605 {
3606         struct extent_buffer *eb = (struct extent_buffer *)page->private;
3607         struct btrfs_inode *btree_ino = BTRFS_I(eb->fs_info->btree_inode);
3608
3609         SetPageError(page);
3610         if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
3611                 return;
3612
3613         /*
3614          * If writeback for a btree extent that doesn't belong to a log tree
3615          * failed, increment the counter transaction->eb_write_errors.
3616          * We do this because while the transaction is running and before it's
3617          * committing (when we call filemap_fdata[write|wait]_range against
3618          * the btree inode), we might have
3619          * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
3620          * returns an error or an error happens during writeback, when we're
3621          * committing the transaction we wouldn't know about it, since the pages
3622          * can be no longer dirty nor marked anymore for writeback (if a
3623          * subsequent modification to the extent buffer didn't happen before the
3624          * transaction commit), which makes filemap_fdata[write|wait]_range not
3625          * able to find the pages tagged with SetPageError at transaction
3626          * commit time. So if this happens we must abort the transaction,
3627          * otherwise we commit a super block with btree roots that point to
3628          * btree nodes/leafs whose content on disk is invalid - either garbage
3629          * or the content of some node/leaf from a past generation that got
3630          * cowed or deleted and is no longer valid.
3631          *
3632          * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
3633          * not be enough - we need to distinguish between log tree extents vs
3634          * non-log tree extents, and the next filemap_fdatawait_range() call
3635          * will catch and clear such errors in the mapping - and that call might
3636          * be from a log sync and not from a transaction commit. Also, checking
3637          * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
3638          * not done and would not be reliable - the eb might have been released
3639          * from memory and reading it back again means that flag would not be
3640          * set (since it's a runtime flag, not persisted on disk).
3641          *
3642          * Using the flags below in the btree inode also makes us achieve the
3643          * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
3644          * writeback for all dirty pages and before filemap_fdatawait_range()
3645          * is called, the writeback for all dirty pages had already finished
3646          * with errors - because we were not using AS_EIO/AS_ENOSPC,
3647          * filemap_fdatawait_range() would return success, as it could not know
3648          * that writeback errors happened (the pages were no longer tagged for
3649          * writeback).
3650          */
3651         switch (eb->log_index) {
3652         case -1:
3653                 set_bit(BTRFS_INODE_BTREE_ERR, &btree_ino->runtime_flags);
3654                 break;
3655         case 0:
3656                 set_bit(BTRFS_INODE_BTREE_LOG1_ERR, &btree_ino->runtime_flags);
3657                 break;
3658         case 1:
3659                 set_bit(BTRFS_INODE_BTREE_LOG2_ERR, &btree_ino->runtime_flags);
3660                 break;
3661         default:
3662                 BUG(); /* unexpected, logic error */
3663         }
3664 }
3665
3666 static void end_bio_extent_buffer_writepage(struct bio *bio, int err)
3667 {
3668         struct bio_vec *bvec;
3669         struct extent_buffer *eb;
3670         int i, done;
3671
3672         bio_for_each_segment_all(bvec, bio, i) {
3673                 struct page *page = bvec->bv_page;
3674
3675                 eb = (struct extent_buffer *)page->private;
3676                 BUG_ON(!eb);
3677                 done = atomic_dec_and_test(&eb->io_pages);
3678
3679                 if (err || test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
3680                         ClearPageUptodate(page);
3681                         set_btree_ioerr(page);
3682                 }
3683
3684                 end_page_writeback(page);
3685
3686                 if (!done)
3687                         continue;
3688
3689                 end_extent_buffer_writeback(eb);
3690         }
3691
3692         bio_put(bio);
3693 }
3694
3695 static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
3696                         struct btrfs_fs_info *fs_info,
3697                         struct writeback_control *wbc,
3698                         struct extent_page_data *epd)
3699 {
3700         struct block_device *bdev = fs_info->fs_devices->latest_bdev;
3701         struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
3702         u64 offset = eb->start;
3703         unsigned long i, num_pages;
3704         unsigned long bio_flags = 0;
3705         int rw = (epd->sync_io ? WRITE_SYNC : WRITE) | REQ_META;
3706         int ret = 0;
3707
3708         clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
3709         num_pages = num_extent_pages(eb->start, eb->len);
3710         atomic_set(&eb->io_pages, num_pages);
3711         if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
3712                 bio_flags = EXTENT_BIO_TREE_LOG;
3713
3714         for (i = 0; i < num_pages; i++) {
3715                 struct page *p = eb->pages[i];
3716
3717                 clear_page_dirty_for_io(p);
3718                 set_page_writeback(p);
3719                 ret = submit_extent_page(rw, tree, p, offset >> 9,
3720                                          PAGE_CACHE_SIZE, 0, bdev, &epd->bio,
3721                                          -1, end_bio_extent_buffer_writepage,
3722                                          0, epd->bio_flags, bio_flags);
3723                 epd->bio_flags = bio_flags;
3724                 if (ret) {
3725                         set_btree_ioerr(p);
3726                         end_page_writeback(p);
3727                         if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
3728                                 end_extent_buffer_writeback(eb);
3729                         ret = -EIO;
3730                         break;
3731                 }
3732                 offset += PAGE_CACHE_SIZE;
3733                 update_nr_written(p, wbc, 1);
3734                 unlock_page(p);
3735         }
3736
3737         if (unlikely(ret)) {
3738                 for (; i < num_pages; i++) {
3739                         struct page *p = eb->pages[i];
3740                         clear_page_dirty_for_io(p);
3741                         unlock_page(p);
3742                 }
3743         }
3744
3745         return ret;
3746 }
3747
3748 int btree_write_cache_pages(struct address_space *mapping,
3749                                    struct writeback_control *wbc)
3750 {
3751         struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
3752         struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
3753         struct extent_buffer *eb, *prev_eb = NULL;
3754         struct extent_page_data epd = {
3755                 .bio = NULL,
3756                 .tree = tree,
3757                 .extent_locked = 0,
3758                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
3759                 .bio_flags = 0,
3760         };
3761         int ret = 0;
3762         int done = 0;
3763         int nr_to_write_done = 0;
3764         struct pagevec pvec;
3765         int nr_pages;
3766         pgoff_t index;
3767         pgoff_t end;            /* Inclusive */
3768         int scanned = 0;
3769         int tag;
3770
3771         pagevec_init(&pvec, 0);
3772         if (wbc->range_cyclic) {
3773                 index = mapping->writeback_index; /* Start from prev offset */
3774                 end = -1;
3775         } else {
3776                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
3777                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
3778                 scanned = 1;
3779         }
3780         if (wbc->sync_mode == WB_SYNC_ALL)
3781                 tag = PAGECACHE_TAG_TOWRITE;
3782         else
3783                 tag = PAGECACHE_TAG_DIRTY;
3784 retry:
3785         if (wbc->sync_mode == WB_SYNC_ALL)
3786                 tag_pages_for_writeback(mapping, index, end);
3787         while (!done && !nr_to_write_done && (index <= end) &&
3788                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3789                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3790                 unsigned i;
3791
3792                 scanned = 1;
3793                 for (i = 0; i < nr_pages; i++) {
3794                         struct page *page = pvec.pages[i];
3795
3796                         if (!PagePrivate(page))
3797                                 continue;
3798
3799                         if (!wbc->range_cyclic && page->index > end) {
3800                                 done = 1;
3801                                 break;
3802                         }
3803
3804                         spin_lock(&mapping->private_lock);
3805                         if (!PagePrivate(page)) {
3806                                 spin_unlock(&mapping->private_lock);
3807                                 continue;
3808                         }
3809
3810                         eb = (struct extent_buffer *)page->private;
3811
3812                         /*
3813                          * Shouldn't happen and normally this would be a BUG_ON
3814                          * but no sense in crashing the users box for something
3815                          * we can survive anyway.
3816                          */
3817                         if (WARN_ON(!eb)) {
3818                                 spin_unlock(&mapping->private_lock);
3819                                 continue;
3820                         }
3821
3822                         if (eb == prev_eb) {
3823                                 spin_unlock(&mapping->private_lock);
3824                                 continue;
3825                         }
3826
3827                         ret = atomic_inc_not_zero(&eb->refs);
3828                         spin_unlock(&mapping->private_lock);
3829                         if (!ret)
3830                                 continue;
3831
3832                         prev_eb = eb;
3833                         ret = lock_extent_buffer_for_io(eb, fs_info, &epd);
3834                         if (!ret) {
3835                                 free_extent_buffer(eb);
3836                                 continue;
3837                         }
3838
3839                         ret = write_one_eb(eb, fs_info, wbc, &epd);
3840                         if (ret) {
3841                                 done = 1;
3842                                 free_extent_buffer(eb);
3843                                 break;
3844                         }
3845                         free_extent_buffer(eb);
3846
3847                         /*
3848                          * the filesystem may choose to bump up nr_to_write.
3849                          * We have to make sure to honor the new nr_to_write
3850                          * at any time
3851                          */
3852                         nr_to_write_done = wbc->nr_to_write <= 0;
3853                 }
3854                 pagevec_release(&pvec);
3855                 cond_resched();
3856         }
3857         if (!scanned && !done) {
3858                 /*
3859                  * We hit the last page and there is more work to be done: wrap
3860                  * back to the start of the file
3861                  */
3862                 scanned = 1;
3863                 index = 0;
3864                 goto retry;
3865         }
3866         flush_write_bio(&epd);
3867         return ret;
3868 }
3869
3870 /**
3871  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
3872  * @mapping: address space structure to write
3873  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
3874  * @writepage: function called for each page
3875  * @data: data passed to writepage function
3876  *
3877  * If a page is already under I/O, write_cache_pages() skips it, even
3878  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
3879  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
3880  * and msync() need to guarantee that all the data which was dirty at the time
3881  * the call was made get new I/O started against them.  If wbc->sync_mode is
3882  * WB_SYNC_ALL then we were called for data integrity and we must wait for
3883  * existing IO to complete.
3884  */
3885 static int extent_write_cache_pages(struct extent_io_tree *tree,
3886                              struct address_space *mapping,
3887                              struct writeback_control *wbc,
3888                              writepage_t writepage, void *data,
3889                              void (*flush_fn)(void *))
3890 {
3891         struct inode *inode = mapping->host;
3892         int ret = 0;
3893         int done = 0;
3894         int err = 0;
3895         int nr_to_write_done = 0;
3896         struct pagevec pvec;
3897         int nr_pages;
3898         pgoff_t index;
3899         pgoff_t end;            /* Inclusive */
3900         int scanned = 0;
3901         int tag;
3902
3903         /*
3904          * We have to hold onto the inode so that ordered extents can do their
3905          * work when the IO finishes.  The alternative to this is failing to add
3906          * an ordered extent if the igrab() fails there and that is a huge pain
3907          * to deal with, so instead just hold onto the inode throughout the
3908          * writepages operation.  If it fails here we are freeing up the inode
3909          * anyway and we'd rather not waste our time writing out stuff that is
3910          * going to be truncated anyway.
3911          */
3912         if (!igrab(inode))
3913                 return 0;
3914
3915         pagevec_init(&pvec, 0);
3916         if (wbc->range_cyclic) {
3917                 index = mapping->writeback_index; /* Start from prev offset */
3918                 end = -1;
3919         } else {
3920                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
3921                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
3922                 scanned = 1;
3923         }
3924         if (wbc->sync_mode == WB_SYNC_ALL)
3925                 tag = PAGECACHE_TAG_TOWRITE;
3926         else
3927                 tag = PAGECACHE_TAG_DIRTY;
3928 retry:
3929         if (wbc->sync_mode == WB_SYNC_ALL)
3930                 tag_pages_for_writeback(mapping, index, end);
3931         while (!done && !nr_to_write_done && (index <= end) &&
3932                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3933                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3934                 unsigned i;
3935
3936                 scanned = 1;
3937                 for (i = 0; i < nr_pages; i++) {
3938                         struct page *page = pvec.pages[i];
3939
3940                         /*
3941                          * At this point we hold neither mapping->tree_lock nor
3942                          * lock on the page itself: the page may be truncated or
3943                          * invalidated (changing page->mapping to NULL), or even
3944                          * swizzled back from swapper_space to tmpfs file
3945                          * mapping
3946                          */
3947                         if (!trylock_page(page)) {
3948                                 flush_fn(data);
3949                                 lock_page(page);
3950                         }
3951
3952                         if (unlikely(page->mapping != mapping)) {
3953                                 unlock_page(page);
3954                                 continue;
3955                         }
3956
3957                         if (!wbc->range_cyclic && page->index > end) {
3958                                 done = 1;
3959                                 unlock_page(page);
3960                                 continue;
3961                         }
3962
3963                         if (wbc->sync_mode != WB_SYNC_NONE) {
3964                                 if (PageWriteback(page))
3965                                         flush_fn(data);
3966                                 wait_on_page_writeback(page);
3967                         }
3968
3969                         if (PageWriteback(page) ||
3970                             !clear_page_dirty_for_io(page)) {
3971                                 unlock_page(page);
3972                                 continue;
3973                         }
3974
3975                         ret = (*writepage)(page, wbc, data);
3976
3977                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
3978                                 unlock_page(page);
3979                                 ret = 0;
3980                         }
3981                         if (!err && ret < 0)
3982                                 err = ret;
3983
3984                         /*
3985                          * the filesystem may choose to bump up nr_to_write.
3986                          * We have to make sure to honor the new nr_to_write
3987                          * at any time
3988                          */
3989                         nr_to_write_done = wbc->nr_to_write <= 0;
3990                 }
3991                 pagevec_release(&pvec);
3992                 cond_resched();
3993         }
3994         if (!scanned && !done && !err) {
3995                 /*
3996                  * We hit the last page and there is more work to be done: wrap
3997                  * back to the start of the file
3998                  */
3999                 scanned = 1;
4000                 index = 0;
4001                 goto retry;
4002         }
4003         btrfs_add_delayed_iput(inode);
4004         return err;
4005 }
4006
4007 static void flush_epd_write_bio(struct extent_page_data *epd)
4008 {
4009         if (epd->bio) {
4010                 int rw = WRITE;
4011                 int ret;
4012
4013                 if (epd->sync_io)
4014                         rw = WRITE_SYNC;
4015
4016                 ret = submit_one_bio(rw, epd->bio, 0, epd->bio_flags);
4017                 BUG_ON(ret < 0); /* -ENOMEM */
4018                 epd->bio = NULL;
4019         }
4020 }
4021
4022 static noinline void flush_write_bio(void *data)
4023 {
4024         struct extent_page_data *epd = data;
4025         flush_epd_write_bio(epd);
4026 }
4027
4028 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
4029                           get_extent_t *get_extent,
4030                           struct writeback_control *wbc)
4031 {
4032         int ret;
4033         struct extent_page_data epd = {
4034                 .bio = NULL,
4035                 .tree = tree,
4036                 .get_extent = get_extent,
4037                 .extent_locked = 0,
4038                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4039                 .bio_flags = 0,
4040         };
4041
4042         ret = __extent_writepage(page, wbc, &epd);
4043
4044         flush_epd_write_bio(&epd);
4045         return ret;
4046 }
4047
4048 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
4049                               u64 start, u64 end, get_extent_t *get_extent,
4050                               int mode)
4051 {
4052         int ret = 0;
4053         struct address_space *mapping = inode->i_mapping;
4054         struct page *page;
4055         unsigned long nr_pages = (end - start + PAGE_CACHE_SIZE) >>
4056                 PAGE_CACHE_SHIFT;
4057
4058         struct extent_page_data epd = {
4059                 .bio = NULL,
4060                 .tree = tree,
4061                 .get_extent = get_extent,
4062                 .extent_locked = 1,
4063                 .sync_io = mode == WB_SYNC_ALL,
4064                 .bio_flags = 0,
4065         };
4066         struct writeback_control wbc_writepages = {
4067                 .sync_mode      = mode,
4068                 .nr_to_write    = nr_pages * 2,
4069                 .range_start    = start,
4070                 .range_end      = end + 1,
4071         };
4072
4073         while (start <= end) {
4074                 page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
4075                 if (clear_page_dirty_for_io(page))
4076                         ret = __extent_writepage(page, &wbc_writepages, &epd);
4077                 else {
4078                         if (tree->ops && tree->ops->writepage_end_io_hook)
4079                                 tree->ops->writepage_end_io_hook(page, start,
4080                                                  start + PAGE_CACHE_SIZE - 1,
4081                                                  NULL, 1);
4082                         unlock_page(page);
4083                 }
4084                 page_cache_release(page);
4085                 start += PAGE_CACHE_SIZE;
4086         }
4087
4088         flush_epd_write_bio(&epd);
4089         return ret;
4090 }
4091
4092 int extent_writepages(struct extent_io_tree *tree,
4093                       struct address_space *mapping,
4094                       get_extent_t *get_extent,
4095                       struct writeback_control *wbc)
4096 {
4097         int ret = 0;
4098         struct extent_page_data epd = {
4099                 .bio = NULL,
4100                 .tree = tree,
4101                 .get_extent = get_extent,
4102                 .extent_locked = 0,
4103                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4104                 .bio_flags = 0,
4105         };
4106
4107         ret = extent_write_cache_pages(tree, mapping, wbc,
4108                                        __extent_writepage, &epd,
4109                                        flush_write_bio);
4110         flush_epd_write_bio(&epd);
4111         return ret;
4112 }
4113
4114 int extent_readpages(struct extent_io_tree *tree,
4115                      struct address_space *mapping,
4116                      struct list_head *pages, unsigned nr_pages,
4117                      get_extent_t get_extent)
4118 {
4119         struct bio *bio = NULL;
4120         unsigned page_idx;
4121         unsigned long bio_flags = 0;
4122         struct page *pagepool[16];
4123         struct page *page;
4124         struct extent_map *em_cached = NULL;
4125         int nr = 0;
4126
4127         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
4128                 page = list_entry(pages->prev, struct page, lru);
4129
4130                 prefetchw(&page->flags);
4131                 list_del(&page->lru);
4132                 if (add_to_page_cache_lru(page, mapping,
4133                                         page->index, GFP_NOFS)) {
4134                         page_cache_release(page);
4135                         continue;
4136                 }
4137
4138                 pagepool[nr++] = page;
4139                 if (nr < ARRAY_SIZE(pagepool))
4140                         continue;
4141                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4142                                    &bio, 0, &bio_flags, READ);
4143                 nr = 0;
4144         }
4145         if (nr)
4146                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4147                                    &bio, 0, &bio_flags, READ);
4148
4149         if (em_cached)
4150                 free_extent_map(em_cached);
4151
4152         BUG_ON(!list_empty(pages));
4153         if (bio)
4154                 return submit_one_bio(READ, bio, 0, bio_flags);
4155         return 0;
4156 }
4157
4158 /*
4159  * basic invalidatepage code, this waits on any locked or writeback
4160  * ranges corresponding to the page, and then deletes any extent state
4161  * records from the tree
4162  */
4163 int extent_invalidatepage(struct extent_io_tree *tree,
4164                           struct page *page, unsigned long offset)
4165 {
4166         struct extent_state *cached_state = NULL;
4167         u64 start = page_offset(page);
4168         u64 end = start + PAGE_CACHE_SIZE - 1;
4169         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
4170
4171         start += ALIGN(offset, blocksize);
4172         if (start > end)
4173                 return 0;
4174
4175         lock_extent_bits(tree, start, end, 0, &cached_state);
4176         wait_on_page_writeback(page);
4177         clear_extent_bit(tree, start, end,
4178                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
4179                          EXTENT_DO_ACCOUNTING,
4180                          1, 1, &cached_state, GFP_NOFS);
4181         return 0;
4182 }
4183
4184 /*
4185  * a helper for releasepage, this tests for areas of the page that
4186  * are locked or under IO and drops the related state bits if it is safe
4187  * to drop the page.
4188  */
4189 static int try_release_extent_state(struct extent_map_tree *map,
4190                                     struct extent_io_tree *tree,
4191                                     struct page *page, gfp_t mask)
4192 {
4193         u64 start = page_offset(page);
4194         u64 end = start + PAGE_CACHE_SIZE - 1;
4195         int ret = 1;
4196
4197         if (test_range_bit(tree, start, end,
4198                            EXTENT_IOBITS, 0, NULL))
4199                 ret = 0;
4200         else {
4201                 if ((mask & GFP_NOFS) == GFP_NOFS)
4202                         mask = GFP_NOFS;
4203                 /*
4204                  * at this point we can safely clear everything except the
4205                  * locked bit and the nodatasum bit
4206                  */
4207                 ret = clear_extent_bit(tree, start, end,
4208                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
4209                                  0, 0, NULL, mask);
4210
4211                 /* if clear_extent_bit failed for enomem reasons,
4212                  * we can't allow the release to continue.
4213                  */
4214                 if (ret < 0)
4215                         ret = 0;
4216                 else
4217                         ret = 1;
4218         }
4219         return ret;
4220 }
4221
4222 /*
4223  * a helper for releasepage.  As long as there are no locked extents
4224  * in the range corresponding to the page, both state records and extent
4225  * map records are removed
4226  */
4227 int try_release_extent_mapping(struct extent_map_tree *map,
4228                                struct extent_io_tree *tree, struct page *page,
4229                                gfp_t mask)
4230 {
4231         struct extent_map *em;
4232         u64 start = page_offset(page);
4233         u64 end = start + PAGE_CACHE_SIZE - 1;
4234
4235         if ((mask & __GFP_WAIT) &&
4236             page->mapping->host->i_size > 16 * 1024 * 1024) {
4237                 u64 len;
4238                 while (start <= end) {
4239                         len = end - start + 1;
4240                         write_lock(&map->lock);
4241                         em = lookup_extent_mapping(map, start, len);
4242                         if (!em) {
4243                                 write_unlock(&map->lock);
4244                                 break;
4245                         }
4246                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
4247                             em->start != start) {
4248                                 write_unlock(&map->lock);
4249                                 free_extent_map(em);
4250                                 break;
4251                         }
4252                         if (!test_range_bit(tree, em->start,
4253                                             extent_map_end(em) - 1,
4254                                             EXTENT_LOCKED | EXTENT_WRITEBACK,
4255                                             0, NULL)) {
4256                                 remove_extent_mapping(map, em);
4257                                 /* once for the rb tree */
4258                                 free_extent_map(em);
4259                         }
4260                         start = extent_map_end(em);
4261                         write_unlock(&map->lock);
4262
4263                         /* once for us */
4264                         free_extent_map(em);
4265                 }
4266         }
4267         return try_release_extent_state(map, tree, page, mask);
4268 }
4269
4270 /*
4271  * helper function for fiemap, which doesn't want to see any holes.
4272  * This maps until we find something past 'last'
4273  */
4274 static struct extent_map *get_extent_skip_holes(struct inode *inode,
4275                                                 u64 offset,
4276                                                 u64 last,
4277                                                 get_extent_t *get_extent)
4278 {
4279         u64 sectorsize = BTRFS_I(inode)->root->sectorsize;
4280         struct extent_map *em;
4281         u64 len;
4282
4283         if (offset >= last)
4284                 return NULL;
4285
4286         while (1) {
4287                 len = last - offset;
4288                 if (len == 0)
4289                         break;
4290                 len = ALIGN(len, sectorsize);
4291                 em = get_extent(inode, NULL, 0, offset, len, 0);
4292                 if (IS_ERR_OR_NULL(em))
4293                         return em;
4294
4295                 /* if this isn't a hole return it */
4296                 if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
4297                     em->block_start != EXTENT_MAP_HOLE) {
4298                         return em;
4299                 }
4300
4301                 /* this is a hole, advance to the next extent */
4302                 offset = extent_map_end(em);
4303                 free_extent_map(em);
4304                 if (offset >= last)
4305                         break;
4306         }
4307         return NULL;
4308 }
4309
4310 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
4311                 __u64 start, __u64 len, get_extent_t *get_extent)
4312 {
4313         int ret = 0;
4314         u64 off = start;
4315         u64 max = start + len;
4316         u32 flags = 0;
4317         u32 found_type;
4318         u64 last;
4319         u64 last_for_get_extent = 0;
4320         u64 disko = 0;
4321         u64 isize = i_size_read(inode);
4322         struct btrfs_key found_key;
4323         struct extent_map *em = NULL;
4324         struct extent_state *cached_state = NULL;
4325         struct btrfs_path *path;
4326         struct btrfs_root *root = BTRFS_I(inode)->root;
4327         int end = 0;
4328         u64 em_start = 0;
4329         u64 em_len = 0;
4330         u64 em_end = 0;
4331
4332         if (len == 0)
4333                 return -EINVAL;
4334
4335         path = btrfs_alloc_path();
4336         if (!path)
4337                 return -ENOMEM;
4338         path->leave_spinning = 1;
4339
4340         start = round_down(start, BTRFS_I(inode)->root->sectorsize);
4341         len = round_up(max, BTRFS_I(inode)->root->sectorsize) - start;
4342
4343         /*
4344          * lookup the last file extent.  We're not using i_size here
4345          * because there might be preallocation past i_size
4346          */
4347         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode), -1,
4348                                        0);
4349         if (ret < 0) {
4350                 btrfs_free_path(path);
4351                 return ret;
4352         }
4353         WARN_ON(!ret);
4354         path->slots[0]--;
4355         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
4356         found_type = found_key.type;
4357
4358         /* No extents, but there might be delalloc bits */
4359         if (found_key.objectid != btrfs_ino(inode) ||
4360             found_type != BTRFS_EXTENT_DATA_KEY) {
4361                 /* have to trust i_size as the end */
4362                 last = (u64)-1;
4363                 last_for_get_extent = isize;
4364         } else {
4365                 /*
4366                  * remember the start of the last extent.  There are a
4367                  * bunch of different factors that go into the length of the
4368                  * extent, so its much less complex to remember where it started
4369                  */
4370                 last = found_key.offset;
4371                 last_for_get_extent = last + 1;
4372         }
4373         btrfs_release_path(path);
4374
4375         /*
4376          * we might have some extents allocated but more delalloc past those
4377          * extents.  so, we trust isize unless the start of the last extent is
4378          * beyond isize
4379          */
4380         if (last < isize) {
4381                 last = (u64)-1;
4382                 last_for_get_extent = isize;
4383         }
4384
4385         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len - 1, 0,
4386                          &cached_state);
4387
4388         em = get_extent_skip_holes(inode, start, last_for_get_extent,
4389                                    get_extent);
4390         if (!em)
4391                 goto out;
4392         if (IS_ERR(em)) {
4393                 ret = PTR_ERR(em);
4394                 goto out;
4395         }
4396
4397         while (!end) {
4398                 u64 offset_in_extent = 0;
4399
4400                 /* break if the extent we found is outside the range */
4401                 if (em->start >= max || extent_map_end(em) < off)
4402                         break;
4403
4404                 /*
4405                  * get_extent may return an extent that starts before our
4406                  * requested range.  We have to make sure the ranges
4407                  * we return to fiemap always move forward and don't
4408                  * overlap, so adjust the offsets here
4409                  */
4410                 em_start = max(em->start, off);
4411
4412                 /*
4413                  * record the offset from the start of the extent
4414                  * for adjusting the disk offset below.  Only do this if the
4415                  * extent isn't compressed since our in ram offset may be past
4416                  * what we have actually allocated on disk.
4417                  */
4418                 if (!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4419                         offset_in_extent = em_start - em->start;
4420                 em_end = extent_map_end(em);
4421                 em_len = em_end - em_start;
4422                 disko = 0;
4423                 flags = 0;
4424
4425                 /*
4426                  * bump off for our next call to get_extent
4427                  */
4428                 off = extent_map_end(em);
4429                 if (off >= max)
4430                         end = 1;
4431
4432                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
4433                         end = 1;
4434                         flags |= FIEMAP_EXTENT_LAST;
4435                 } else if (em->block_start == EXTENT_MAP_INLINE) {
4436                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
4437                                   FIEMAP_EXTENT_NOT_ALIGNED);
4438                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
4439                         flags |= (FIEMAP_EXTENT_DELALLOC |
4440                                   FIEMAP_EXTENT_UNKNOWN);
4441                 } else if (fieinfo->fi_extents_max) {
4442                         u64 bytenr = em->block_start -
4443                                 (em->start - em->orig_start);
4444
4445                         disko = em->block_start + offset_in_extent;
4446
4447                         /*
4448                          * As btrfs supports shared space, this information
4449                          * can be exported to userspace tools via
4450                          * flag FIEMAP_EXTENT_SHARED.  If fi_extents_max == 0
4451                          * then we're just getting a count and we can skip the
4452                          * lookup stuff.
4453                          */
4454                         ret = btrfs_check_shared(NULL, root->fs_info,
4455                                                  root->objectid,
4456                                                  btrfs_ino(inode), bytenr);
4457                         if (ret < 0)
4458                                 goto out_free;
4459                         if (ret)
4460                                 flags |= FIEMAP_EXTENT_SHARED;
4461                         ret = 0;
4462                 }
4463                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4464                         flags |= FIEMAP_EXTENT_ENCODED;
4465
4466                 free_extent_map(em);
4467                 em = NULL;
4468                 if ((em_start >= last) || em_len == (u64)-1 ||
4469                    (last == (u64)-1 && isize <= em_end)) {
4470                         flags |= FIEMAP_EXTENT_LAST;
4471                         end = 1;
4472                 }
4473
4474                 /* now scan forward to see if this is really the last extent. */
4475                 em = get_extent_skip_holes(inode, off, last_for_get_extent,
4476                                            get_extent);
4477                 if (IS_ERR(em)) {
4478                         ret = PTR_ERR(em);
4479                         goto out;
4480                 }
4481                 if (!em) {
4482                         flags |= FIEMAP_EXTENT_LAST;
4483                         end = 1;
4484                 }
4485                 ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
4486                                               em_len, flags);
4487                 if (ret)
4488                         goto out_free;
4489         }
4490 out_free:
4491         free_extent_map(em);
4492 out:
4493         btrfs_free_path(path);
4494         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4495                              &cached_state, GFP_NOFS);
4496         return ret;
4497 }
4498
4499 static void __free_extent_buffer(struct extent_buffer *eb)
4500 {
4501         btrfs_leak_debug_del(&eb->leak_list);
4502         kmem_cache_free(extent_buffer_cache, eb);
4503 }
4504
4505 int extent_buffer_under_io(struct extent_buffer *eb)
4506 {
4507         return (atomic_read(&eb->io_pages) ||
4508                 test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
4509                 test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4510 }
4511
4512 /*
4513  * Helper for releasing extent buffer page.
4514  */
4515 static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
4516 {
4517         unsigned long index;
4518         struct page *page;
4519         int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4520
4521         BUG_ON(extent_buffer_under_io(eb));
4522
4523         index = num_extent_pages(eb->start, eb->len);
4524         if (index == 0)
4525                 return;
4526
4527         do {
4528                 index--;
4529                 page = eb->pages[index];
4530                 if (page && mapped) {
4531                         spin_lock(&page->mapping->private_lock);
4532                         /*
4533                          * We do this since we'll remove the pages after we've
4534                          * removed the eb from the radix tree, so we could race
4535                          * and have this page now attached to the new eb.  So
4536                          * only clear page_private if it's still connected to
4537                          * this eb.
4538                          */
4539                         if (PagePrivate(page) &&
4540                             page->private == (unsigned long)eb) {
4541                                 BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4542                                 BUG_ON(PageDirty(page));
4543                                 BUG_ON(PageWriteback(page));
4544                                 /*
4545                                  * We need to make sure we haven't be attached
4546                                  * to a new eb.
4547                                  */
4548                                 ClearPagePrivate(page);
4549                                 set_page_private(page, 0);
4550                                 /* One for the page private */
4551                                 page_cache_release(page);
4552                         }
4553                         spin_unlock(&page->mapping->private_lock);
4554
4555                 }
4556                 if (page) {
4557                         /* One for when we alloced the page */
4558                         page_cache_release(page);
4559                 }
4560         } while (index != 0);
4561 }
4562
4563 /*
4564  * Helper for releasing the extent buffer.
4565  */
4566 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
4567 {
4568         btrfs_release_extent_buffer_page(eb);
4569         __free_extent_buffer(eb);
4570 }
4571
4572 static struct extent_buffer *
4573 __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
4574                       unsigned long len, gfp_t mask)
4575 {
4576         struct extent_buffer *eb = NULL;
4577
4578         eb = kmem_cache_zalloc(extent_buffer_cache, mask);
4579         if (eb == NULL)
4580                 return NULL;
4581         eb->start = start;
4582         eb->len = len;
4583         eb->fs_info = fs_info;
4584         eb->bflags = 0;
4585         rwlock_init(&eb->lock);
4586         atomic_set(&eb->write_locks, 0);
4587         atomic_set(&eb->read_locks, 0);
4588         atomic_set(&eb->blocking_readers, 0);
4589         atomic_set(&eb->blocking_writers, 0);
4590         atomic_set(&eb->spinning_readers, 0);
4591         atomic_set(&eb->spinning_writers, 0);
4592         eb->lock_nested = 0;
4593         init_waitqueue_head(&eb->write_lock_wq);
4594         init_waitqueue_head(&eb->read_lock_wq);
4595
4596         btrfs_leak_debug_add(&eb->leak_list, &buffers);
4597
4598         spin_lock_init(&eb->refs_lock);
4599         atomic_set(&eb->refs, 1);
4600         atomic_set(&eb->io_pages, 0);
4601
4602         /*
4603          * Sanity checks, currently the maximum is 64k covered by 16x 4k pages
4604          */
4605         BUILD_BUG_ON(BTRFS_MAX_METADATA_BLOCKSIZE
4606                 > MAX_INLINE_EXTENT_BUFFER_SIZE);
4607         BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
4608
4609         return eb;
4610 }
4611
4612 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
4613 {
4614         unsigned long i;
4615         struct page *p;
4616         struct extent_buffer *new;
4617         unsigned long num_pages = num_extent_pages(src->start, src->len);
4618
4619         new = __alloc_extent_buffer(NULL, src->start, src->len, GFP_NOFS);
4620         if (new == NULL)
4621                 return NULL;
4622
4623         for (i = 0; i < num_pages; i++) {
4624                 p = alloc_page(GFP_NOFS);
4625                 if (!p) {
4626                         btrfs_release_extent_buffer(new);
4627                         return NULL;
4628                 }
4629                 attach_extent_buffer_page(new, p);
4630                 WARN_ON(PageDirty(p));
4631                 SetPageUptodate(p);
4632                 new->pages[i] = p;
4633         }
4634
4635         copy_extent_buffer(new, src, 0, 0, src->len);
4636         set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
4637         set_bit(EXTENT_BUFFER_DUMMY, &new->bflags);
4638
4639         return new;
4640 }
4641
4642 struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len)
4643 {
4644         struct extent_buffer *eb;
4645         unsigned long num_pages = num_extent_pages(0, len);
4646         unsigned long i;
4647
4648         eb = __alloc_extent_buffer(NULL, start, len, GFP_NOFS);
4649         if (!eb)
4650                 return NULL;
4651
4652         for (i = 0; i < num_pages; i++) {
4653                 eb->pages[i] = alloc_page(GFP_NOFS);
4654                 if (!eb->pages[i])
4655                         goto err;
4656         }
4657         set_extent_buffer_uptodate(eb);
4658         btrfs_set_header_nritems(eb, 0);
4659         set_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4660
4661         return eb;
4662 err:
4663         for (; i > 0; i--)
4664                 __free_page(eb->pages[i - 1]);
4665         __free_extent_buffer(eb);
4666         return NULL;
4667 }
4668
4669 static void check_buffer_tree_ref(struct extent_buffer *eb)
4670 {
4671         int refs;
4672         /* the ref bit is tricky.  We have to make sure it is set
4673          * if we have the buffer dirty.   Otherwise the
4674          * code to free a buffer can end up dropping a dirty
4675          * page
4676          *
4677          * Once the ref bit is set, it won't go away while the
4678          * buffer is dirty or in writeback, and it also won't
4679          * go away while we have the reference count on the
4680          * eb bumped.
4681          *
4682          * We can't just set the ref bit without bumping the
4683          * ref on the eb because free_extent_buffer might
4684          * see the ref bit and try to clear it.  If this happens
4685          * free_extent_buffer might end up dropping our original
4686          * ref by mistake and freeing the page before we are able
4687          * to add one more ref.
4688          *
4689          * So bump the ref count first, then set the bit.  If someone
4690          * beat us to it, drop the ref we added.
4691          */
4692         refs = atomic_read(&eb->refs);
4693         if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4694                 return;
4695
4696         spin_lock(&eb->refs_lock);
4697         if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4698                 atomic_inc(&eb->refs);
4699         spin_unlock(&eb->refs_lock);
4700 }
4701
4702 static void mark_extent_buffer_accessed(struct extent_buffer *eb,
4703                 struct page *accessed)
4704 {
4705         unsigned long num_pages, i;
4706
4707         check_buffer_tree_ref(eb);
4708
4709         num_pages = num_extent_pages(eb->start, eb->len);
4710         for (i = 0; i < num_pages; i++) {
4711                 struct page *p = eb->pages[i];
4712
4713                 if (p != accessed)
4714                         mark_page_accessed(p);
4715         }
4716 }
4717
4718 struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
4719                                          u64 start)
4720 {
4721         struct extent_buffer *eb;
4722
4723         rcu_read_lock();
4724         eb = radix_tree_lookup(&fs_info->buffer_radix,
4725                                start >> PAGE_CACHE_SHIFT);
4726         if (eb && atomic_inc_not_zero(&eb->refs)) {
4727                 rcu_read_unlock();
4728                 mark_extent_buffer_accessed(eb, NULL);
4729                 return eb;
4730         }
4731         rcu_read_unlock();
4732
4733         return NULL;
4734 }
4735
4736 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
4737 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
4738                                                u64 start, unsigned long len)
4739 {
4740         struct extent_buffer *eb, *exists = NULL;
4741         int ret;
4742
4743         eb = find_extent_buffer(fs_info, start);
4744         if (eb)
4745                 return eb;
4746         eb = alloc_dummy_extent_buffer(start, len);
4747         if (!eb)
4748                 return NULL;
4749         eb->fs_info = fs_info;
4750 again:
4751         ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
4752         if (ret)
4753                 goto free_eb;
4754         spin_lock(&fs_info->buffer_lock);
4755         ret = radix_tree_insert(&fs_info->buffer_radix,
4756                                 start >> PAGE_CACHE_SHIFT, eb);
4757         spin_unlock(&fs_info->buffer_lock);
4758         radix_tree_preload_end();
4759         if (ret == -EEXIST) {
4760                 exists = find_extent_buffer(fs_info, start);
4761                 if (exists)
4762                         goto free_eb;
4763                 else
4764                         goto again;
4765         }
4766         check_buffer_tree_ref(eb);
4767         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4768
4769         /*
4770          * We will free dummy extent buffer's if they come into
4771          * free_extent_buffer with a ref count of 2, but if we are using this we
4772          * want the buffers to stay in memory until we're done with them, so
4773          * bump the ref count again.
4774          */
4775         atomic_inc(&eb->refs);
4776         return eb;
4777 free_eb:
4778         btrfs_release_extent_buffer(eb);
4779         return exists;
4780 }
4781 #endif
4782
4783 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
4784                                           u64 start, unsigned long len)
4785 {
4786         unsigned long num_pages = num_extent_pages(start, len);
4787         unsigned long i;
4788         unsigned long index = start >> PAGE_CACHE_SHIFT;
4789         struct extent_buffer *eb;
4790         struct extent_buffer *exists = NULL;
4791         struct page *p;
4792         struct address_space *mapping = fs_info->btree_inode->i_mapping;
4793         int uptodate = 1;
4794         int ret;
4795
4796         eb = find_extent_buffer(fs_info, start);
4797         if (eb)
4798                 return eb;
4799
4800         eb = __alloc_extent_buffer(fs_info, start, len, GFP_NOFS);
4801         if (!eb)
4802                 return NULL;
4803
4804         for (i = 0; i < num_pages; i++, index++) {
4805                 p = find_or_create_page(mapping, index, GFP_NOFS);
4806                 if (!p)
4807                         goto free_eb;
4808
4809                 spin_lock(&mapping->private_lock);
4810                 if (PagePrivate(p)) {
4811                         /*
4812                          * We could have already allocated an eb for this page
4813                          * and attached one so lets see if we can get a ref on
4814                          * the existing eb, and if we can we know it's good and
4815                          * we can just return that one, else we know we can just
4816                          * overwrite page->private.
4817                          */
4818                         exists = (struct extent_buffer *)p->private;
4819                         if (atomic_inc_not_zero(&exists->refs)) {
4820                                 spin_unlock(&mapping->private_lock);
4821                                 unlock_page(p);
4822                                 page_cache_release(p);
4823                                 mark_extent_buffer_accessed(exists, p);
4824                                 goto free_eb;
4825                         }
4826
4827                         /*
4828                          * Do this so attach doesn't complain and we need to
4829                          * drop the ref the old guy had.
4830                          */
4831                         ClearPagePrivate(p);
4832                         WARN_ON(PageDirty(p));
4833                         page_cache_release(p);
4834                 }
4835                 attach_extent_buffer_page(eb, p);
4836                 spin_unlock(&mapping->private_lock);
4837                 WARN_ON(PageDirty(p));
4838                 eb->pages[i] = p;
4839                 if (!PageUptodate(p))
4840                         uptodate = 0;
4841
4842                 /*
4843                  * see below about how we avoid a nasty race with release page
4844                  * and why we unlock later
4845                  */
4846         }
4847         if (uptodate)
4848                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
4849 again:
4850         ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
4851         if (ret)
4852                 goto free_eb;
4853
4854         spin_lock(&fs_info->buffer_lock);
4855         ret = radix_tree_insert(&fs_info->buffer_radix,
4856                                 start >> PAGE_CACHE_SHIFT, eb);
4857         spin_unlock(&fs_info->buffer_lock);
4858         radix_tree_preload_end();
4859         if (ret == -EEXIST) {
4860                 exists = find_extent_buffer(fs_info, start);
4861                 if (exists)
4862                         goto free_eb;
4863                 else
4864                         goto again;
4865         }
4866         /* add one reference for the tree */
4867         check_buffer_tree_ref(eb);
4868         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4869
4870         /*
4871          * there is a race where release page may have
4872          * tried to find this extent buffer in the radix
4873          * but failed.  It will tell the VM it is safe to
4874          * reclaim the, and it will clear the page private bit.
4875          * We must make sure to set the page private bit properly
4876          * after the extent buffer is in the radix tree so
4877          * it doesn't get lost
4878          */
4879         SetPageChecked(eb->pages[0]);
4880         for (i = 1; i < num_pages; i++) {
4881                 p = eb->pages[i];
4882                 ClearPageChecked(p);
4883                 unlock_page(p);
4884         }
4885         unlock_page(eb->pages[0]);
4886         return eb;
4887
4888 free_eb:
4889         for (i = 0; i < num_pages; i++) {
4890                 if (eb->pages[i])
4891                         unlock_page(eb->pages[i]);
4892         }
4893
4894         WARN_ON(!atomic_dec_and_test(&eb->refs));
4895         btrfs_release_extent_buffer(eb);
4896         return exists;
4897 }
4898
4899 static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
4900 {
4901         struct extent_buffer *eb =
4902                         container_of(head, struct extent_buffer, rcu_head);
4903
4904         __free_extent_buffer(eb);
4905 }
4906
4907 /* Expects to have eb->eb_lock already held */
4908 static int release_extent_buffer(struct extent_buffer *eb)
4909 {
4910         WARN_ON(atomic_read(&eb->refs) == 0);
4911         if (atomic_dec_and_test(&eb->refs)) {
4912                 if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) {
4913                         struct btrfs_fs_info *fs_info = eb->fs_info;
4914
4915                         spin_unlock(&eb->refs_lock);
4916
4917                         spin_lock(&fs_info->buffer_lock);
4918                         radix_tree_delete(&fs_info->buffer_radix,
4919                                           eb->start >> PAGE_CACHE_SHIFT);
4920                         spin_unlock(&fs_info->buffer_lock);
4921                 } else {
4922                         spin_unlock(&eb->refs_lock);
4923                 }
4924
4925                 /* Should be safe to release our pages at this point */
4926                 btrfs_release_extent_buffer_page(eb);
4927                 call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
4928                 return 1;
4929         }
4930         spin_unlock(&eb->refs_lock);
4931
4932         return 0;
4933 }
4934
4935 void free_extent_buffer(struct extent_buffer *eb)
4936 {
4937         int refs;
4938         int old;
4939         if (!eb)
4940                 return;
4941
4942         while (1) {
4943                 refs = atomic_read(&eb->refs);
4944                 if (refs <= 3)
4945                         break;
4946                 old = atomic_cmpxchg(&eb->refs, refs, refs - 1);
4947                 if (old == refs)
4948                         return;
4949         }
4950
4951         spin_lock(&eb->refs_lock);
4952         if (atomic_read(&eb->refs) == 2 &&
4953             test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))
4954                 atomic_dec(&eb->refs);
4955
4956         if (atomic_read(&eb->refs) == 2 &&
4957             test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
4958             !extent_buffer_under_io(eb) &&
4959             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4960                 atomic_dec(&eb->refs);
4961
4962         /*
4963          * I know this is terrible, but it's temporary until we stop tracking
4964          * the uptodate bits and such for the extent buffers.
4965          */
4966         release_extent_buffer(eb);
4967 }
4968
4969 void free_extent_buffer_stale(struct extent_buffer *eb)
4970 {
4971         if (!eb)
4972                 return;
4973
4974         spin_lock(&eb->refs_lock);
4975         set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
4976
4977         if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
4978             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4979                 atomic_dec(&eb->refs);
4980         release_extent_buffer(eb);
4981 }
4982
4983 void clear_extent_buffer_dirty(struct extent_buffer *eb)
4984 {
4985         unsigned long i;
4986         unsigned long num_pages;
4987         struct page *page;
4988
4989         num_pages = num_extent_pages(eb->start, eb->len);
4990
4991         for (i = 0; i < num_pages; i++) {
4992                 page = eb->pages[i];
4993                 if (!PageDirty(page))
4994                         continue;
4995
4996                 lock_page(page);
4997                 WARN_ON(!PagePrivate(page));
4998
4999                 clear_page_dirty_for_io(page);
5000                 spin_lock_irq(&page->mapping->tree_lock);
5001                 if (!PageDirty(page)) {
5002                         radix_tree_tag_clear(&page->mapping->page_tree,
5003                                                 page_index(page),
5004                                                 PAGECACHE_TAG_DIRTY);
5005                 }
5006                 spin_unlock_irq(&page->mapping->tree_lock);
5007                 ClearPageError(page);
5008                 unlock_page(page);
5009         }
5010         WARN_ON(atomic_read(&eb->refs) == 0);
5011 }
5012
5013 int set_extent_buffer_dirty(struct extent_buffer *eb)
5014 {
5015         unsigned long i;
5016         unsigned long num_pages;
5017         int was_dirty = 0;
5018
5019         check_buffer_tree_ref(eb);
5020
5021         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
5022
5023         num_pages = num_extent_pages(eb->start, eb->len);
5024         WARN_ON(atomic_read(&eb->refs) == 0);
5025         WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
5026
5027         for (i = 0; i < num_pages; i++)
5028                 set_page_dirty(eb->pages[i]);
5029         return was_dirty;
5030 }
5031
5032 int clear_extent_buffer_uptodate(struct extent_buffer *eb)
5033 {
5034         unsigned long i;
5035         struct page *page;
5036         unsigned long num_pages;
5037
5038         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5039         num_pages = num_extent_pages(eb->start, eb->len);
5040         for (i = 0; i < num_pages; i++) {
5041                 page = eb->pages[i];
5042                 if (page)
5043                         ClearPageUptodate(page);
5044         }
5045         return 0;
5046 }
5047
5048 int set_extent_buffer_uptodate(struct extent_buffer *eb)
5049 {
5050         unsigned long i;
5051         struct page *page;
5052         unsigned long num_pages;
5053
5054         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5055         num_pages = num_extent_pages(eb->start, eb->len);
5056         for (i = 0; i < num_pages; i++) {
5057                 page = eb->pages[i];
5058                 SetPageUptodate(page);
5059         }
5060         return 0;
5061 }
5062
5063 int extent_buffer_uptodate(struct extent_buffer *eb)
5064 {
5065         return test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5066 }
5067
5068 int read_extent_buffer_pages(struct extent_io_tree *tree,
5069                              struct extent_buffer *eb, u64 start, int wait,
5070                              get_extent_t *get_extent, int mirror_num)
5071 {
5072         unsigned long i;
5073         unsigned long start_i;
5074         struct page *page;
5075         int err;
5076         int ret = 0;
5077         int locked_pages = 0;
5078         int all_uptodate = 1;
5079         unsigned long num_pages;
5080         unsigned long num_reads = 0;
5081         struct bio *bio = NULL;
5082         unsigned long bio_flags = 0;
5083
5084         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
5085                 return 0;
5086
5087         if (start) {
5088                 WARN_ON(start < eb->start);
5089                 start_i = (start >> PAGE_CACHE_SHIFT) -
5090                         (eb->start >> PAGE_CACHE_SHIFT);
5091         } else {
5092                 start_i = 0;
5093         }
5094
5095         num_pages = num_extent_pages(eb->start, eb->len);
5096         for (i = start_i; i < num_pages; i++) {
5097                 page = eb->pages[i];
5098                 if (wait == WAIT_NONE) {
5099                         if (!trylock_page(page))
5100                                 goto unlock_exit;
5101                 } else {
5102                         lock_page(page);
5103                 }
5104                 locked_pages++;
5105                 if (!PageUptodate(page)) {
5106                         num_reads++;
5107                         all_uptodate = 0;
5108                 }
5109         }
5110         if (all_uptodate) {
5111                 if (start_i == 0)
5112                         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5113                 goto unlock_exit;
5114         }
5115
5116         clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
5117         eb->read_mirror = 0;
5118         atomic_set(&eb->io_pages, num_reads);
5119         for (i = start_i; i < num_pages; i++) {
5120                 page = eb->pages[i];
5121                 if (!PageUptodate(page)) {
5122                         ClearPageError(page);
5123                         err = __extent_read_full_page(tree, page,
5124                                                       get_extent, &bio,
5125                                                       mirror_num, &bio_flags,
5126                                                       READ | REQ_META);
5127                         if (err)
5128                                 ret = err;
5129                 } else {
5130                         unlock_page(page);
5131                 }
5132         }
5133
5134         if (bio) {
5135                 err = submit_one_bio(READ | REQ_META, bio, mirror_num,
5136                                      bio_flags);
5137                 if (err)
5138                         return err;
5139         }
5140
5141         if (ret || wait != WAIT_COMPLETE)
5142                 return ret;
5143
5144         for (i = start_i; i < num_pages; i++) {
5145                 page = eb->pages[i];
5146                 wait_on_page_locked(page);
5147                 if (!PageUptodate(page))
5148                         ret = -EIO;
5149         }
5150
5151         return ret;
5152
5153 unlock_exit:
5154         i = start_i;
5155         while (locked_pages > 0) {
5156                 page = eb->pages[i];
5157                 i++;
5158                 unlock_page(page);
5159                 locked_pages--;
5160         }
5161         return ret;
5162 }
5163
5164 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
5165                         unsigned long start,
5166                         unsigned long len)
5167 {
5168         size_t cur;
5169         size_t offset;
5170         struct page *page;
5171         char *kaddr;
5172         char *dst = (char *)dstv;
5173         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5174         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5175
5176         WARN_ON(start > eb->len);
5177         WARN_ON(start + len > eb->start + eb->len);
5178
5179         offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5180
5181         while (len > 0) {
5182                 page = eb->pages[i];
5183
5184                 cur = min(len, (PAGE_CACHE_SIZE - offset));
5185                 kaddr = page_address(page);
5186                 memcpy(dst, kaddr + offset, cur);
5187
5188                 dst += cur;
5189                 len -= cur;
5190                 offset = 0;
5191                 i++;
5192         }
5193 }
5194
5195 int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
5196                         unsigned long start,
5197                         unsigned long len)
5198 {
5199         size_t cur;
5200         size_t offset;
5201         struct page *page;
5202         char *kaddr;
5203         char __user *dst = (char __user *)dstv;
5204         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5205         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5206         int ret = 0;
5207
5208         WARN_ON(start > eb->len);
5209         WARN_ON(start + len > eb->start + eb->len);
5210
5211         offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5212
5213         while (len > 0) {
5214                 page = eb->pages[i];
5215
5216                 cur = min(len, (PAGE_CACHE_SIZE - offset));
5217                 kaddr = page_address(page);
5218                 if (copy_to_user(dst, kaddr + offset, cur)) {
5219                         ret = -EFAULT;
5220                         break;
5221                 }
5222
5223                 dst += cur;
5224                 len -= cur;
5225                 offset = 0;
5226                 i++;
5227         }
5228
5229         return ret;
5230 }
5231
5232 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
5233                                unsigned long min_len, char **map,
5234                                unsigned long *map_start,
5235                                unsigned long *map_len)
5236 {
5237         size_t offset = start & (PAGE_CACHE_SIZE - 1);
5238         char *kaddr;
5239         struct page *p;
5240         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5241         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5242         unsigned long end_i = (start_offset + start + min_len - 1) >>
5243                 PAGE_CACHE_SHIFT;
5244
5245         if (i != end_i)
5246                 return -EINVAL;
5247
5248         if (i == 0) {
5249                 offset = start_offset;
5250                 *map_start = 0;
5251         } else {
5252                 offset = 0;
5253                 *map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
5254         }
5255
5256         if (start + min_len > eb->len) {
5257                 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, "
5258                        "wanted %lu %lu\n",
5259                        eb->start, eb->len, start, min_len);
5260                 return -EINVAL;
5261         }
5262
5263         p = eb->pages[i];
5264         kaddr = page_address(p);
5265         *map = kaddr + offset;
5266         *map_len = PAGE_CACHE_SIZE - offset;
5267         return 0;
5268 }
5269
5270 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
5271                           unsigned long start,
5272                           unsigned long len)
5273 {
5274         size_t cur;
5275         size_t offset;
5276         struct page *page;
5277         char *kaddr;
5278         char *ptr = (char *)ptrv;
5279         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5280         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5281         int ret = 0;
5282
5283         WARN_ON(start > eb->len);
5284         WARN_ON(start + len > eb->start + eb->len);
5285
5286         offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5287
5288         while (len > 0) {
5289                 page = eb->pages[i];
5290
5291                 cur = min(len, (PAGE_CACHE_SIZE - offset));
5292
5293                 kaddr = page_address(page);
5294                 ret = memcmp(ptr, kaddr + offset, cur);
5295                 if (ret)
5296                         break;
5297
5298                 ptr += cur;
5299                 len -= cur;
5300                 offset = 0;
5301                 i++;
5302         }
5303         return ret;
5304 }
5305
5306 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
5307                          unsigned long start, unsigned long len)
5308 {
5309         size_t cur;
5310         size_t offset;
5311         struct page *page;
5312         char *kaddr;
5313         char *src = (char *)srcv;
5314         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5315         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5316
5317         WARN_ON(start > eb->len);
5318         WARN_ON(start + len > eb->start + eb->len);
5319
5320         offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5321
5322         while (len > 0) {
5323                 page = eb->pages[i];
5324                 WARN_ON(!PageUptodate(page));
5325
5326                 cur = min(len, PAGE_CACHE_SIZE - offset);
5327                 kaddr = page_address(page);
5328                 memcpy(kaddr + offset, src, cur);
5329
5330                 src += cur;
5331                 len -= cur;
5332                 offset = 0;
5333                 i++;
5334         }
5335 }
5336
5337 void memset_extent_buffer(struct extent_buffer *eb, char c,
5338                           unsigned long start, unsigned long len)
5339 {
5340         size_t cur;
5341         size_t offset;
5342         struct page *page;
5343         char *kaddr;
5344         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5345         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5346
5347         WARN_ON(start > eb->len);
5348         WARN_ON(start + len > eb->start + eb->len);
5349
5350         offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5351
5352         while (len > 0) {
5353                 page = eb->pages[i];
5354                 WARN_ON(!PageUptodate(page));
5355
5356                 cur = min(len, PAGE_CACHE_SIZE - offset);
5357                 kaddr = page_address(page);
5358                 memset(kaddr + offset, c, cur);
5359
5360                 len -= cur;
5361                 offset = 0;
5362                 i++;
5363         }
5364 }
5365
5366 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
5367                         unsigned long dst_offset, unsigned long src_offset,
5368                         unsigned long len)
5369 {
5370         u64 dst_len = dst->len;
5371         size_t cur;
5372         size_t offset;
5373         struct page *page;
5374         char *kaddr;
5375         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
5376         unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
5377
5378         WARN_ON(src->len != dst_len);
5379
5380         offset = (start_offset + dst_offset) &
5381                 (PAGE_CACHE_SIZE - 1);
5382
5383         while (len > 0) {
5384                 page = dst->pages[i];
5385                 WARN_ON(!PageUptodate(page));
5386
5387                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
5388
5389                 kaddr = page_address(page);
5390                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
5391
5392                 src_offset += cur;
5393                 len -= cur;
5394                 offset = 0;
5395                 i++;
5396         }
5397 }
5398
5399 static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
5400 {
5401         unsigned long distance = (src > dst) ? src - dst : dst - src;
5402         return distance < len;
5403 }
5404
5405 static void copy_pages(struct page *dst_page, struct page *src_page,
5406                        unsigned long dst_off, unsigned long src_off,
5407                        unsigned long len)
5408 {
5409         char *dst_kaddr = page_address(dst_page);
5410         char *src_kaddr;
5411         int must_memmove = 0;
5412
5413         if (dst_page != src_page) {
5414                 src_kaddr = page_address(src_page);
5415         } else {
5416                 src_kaddr = dst_kaddr;
5417                 if (areas_overlap(src_off, dst_off, len))
5418                         must_memmove = 1;
5419         }
5420
5421         if (must_memmove)
5422                 memmove(dst_kaddr + dst_off, src_kaddr + src_off, len);
5423         else
5424                 memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
5425 }
5426
5427 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5428                            unsigned long src_offset, unsigned long len)
5429 {
5430         size_t cur;
5431         size_t dst_off_in_page;
5432         size_t src_off_in_page;
5433         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
5434         unsigned long dst_i;
5435         unsigned long src_i;
5436
5437         if (src_offset + len > dst->len) {
5438                 printk(KERN_ERR "BTRFS: memmove bogus src_offset %lu move "
5439                        "len %lu dst len %lu\n", src_offset, len, dst->len);
5440                 BUG_ON(1);
5441         }
5442         if (dst_offset + len > dst->len) {
5443                 printk(KERN_ERR "BTRFS: memmove bogus dst_offset %lu move "
5444                        "len %lu dst len %lu\n", dst_offset, len, dst->len);
5445                 BUG_ON(1);
5446         }
5447
5448         while (len > 0) {
5449                 dst_off_in_page = (start_offset + dst_offset) &
5450                         (PAGE_CACHE_SIZE - 1);
5451                 src_off_in_page = (start_offset + src_offset) &
5452                         (PAGE_CACHE_SIZE - 1);
5453
5454                 dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
5455                 src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
5456
5457                 cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
5458                                                src_off_in_page));
5459                 cur = min_t(unsigned long, cur,
5460                         (unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
5461
5462                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
5463                            dst_off_in_page, src_off_in_page, cur);
5464
5465                 src_offset += cur;
5466                 dst_offset += cur;
5467                 len -= cur;
5468         }
5469 }
5470
5471 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5472                            unsigned long src_offset, unsigned long len)
5473 {
5474         size_t cur;
5475         size_t dst_off_in_page;
5476         size_t src_off_in_page;
5477         unsigned long dst_end = dst_offset + len - 1;
5478         unsigned long src_end = src_offset + len - 1;
5479         size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
5480         unsigned long dst_i;
5481         unsigned long src_i;
5482
5483         if (src_offset + len > dst->len) {
5484                 printk(KERN_ERR "BTRFS: memmove bogus src_offset %lu move "
5485                        "len %lu len %lu\n", src_offset, len, dst->len);
5486                 BUG_ON(1);
5487         }
5488         if (dst_offset + len > dst->len) {
5489                 printk(KERN_ERR "BTRFS: memmove bogus dst_offset %lu move "
5490                        "len %lu len %lu\n", dst_offset, len, dst->len);
5491                 BUG_ON(1);
5492         }
5493         if (dst_offset < src_offset) {
5494                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
5495                 return;
5496         }
5497         while (len > 0) {
5498                 dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
5499                 src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
5500
5501                 dst_off_in_page = (start_offset + dst_end) &
5502                         (PAGE_CACHE_SIZE - 1);
5503                 src_off_in_page = (start_offset + src_end) &
5504                         (PAGE_CACHE_SIZE - 1);
5505
5506                 cur = min_t(unsigned long, len, src_off_in_page + 1);
5507                 cur = min(cur, dst_off_in_page + 1);
5508                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
5509                            dst_off_in_page - cur + 1,
5510                            src_off_in_page - cur + 1, cur);
5511
5512                 dst_end -= cur;
5513                 src_end -= cur;
5514                 len -= cur;
5515         }
5516 }
5517
5518 int try_release_extent_buffer(struct page *page)
5519 {
5520         struct extent_buffer *eb;
5521
5522         /*
5523          * We need to make sure noboody is attaching this page to an eb right
5524          * now.
5525          */
5526         spin_lock(&page->mapping->private_lock);
5527         if (!PagePrivate(page)) {
5528                 spin_unlock(&page->mapping->private_lock);
5529                 return 1;
5530         }
5531
5532         eb = (struct extent_buffer *)page->private;
5533         BUG_ON(!eb);
5534
5535         /*
5536          * This is a little awful but should be ok, we need to make sure that
5537          * the eb doesn't disappear out from under us while we're looking at
5538          * this page.
5539          */
5540         spin_lock(&eb->refs_lock);
5541         if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
5542                 spin_unlock(&eb->refs_lock);
5543                 spin_unlock(&page->mapping->private_lock);
5544                 return 0;
5545         }
5546         spin_unlock(&page->mapping->private_lock);
5547
5548         /*
5549          * If tree ref isn't set then we know the ref on this eb is a real ref,
5550          * so just return, this page will likely be freed soon anyway.
5551          */
5552         if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
5553                 spin_unlock(&eb->refs_lock);
5554                 return 0;
5555         }
5556
5557         return release_extent_buffer(eb);
5558 }