fs/btrfs/extent_io.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/bitops.h>
   3 #include <linux/slab.h>
   4 #include <linux/bio.h>
   5 #include <linux/mm.h>
   6 #include <linux/pagemap.h>
   7 #include <linux/page-flags.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/swap.h>
  11 #include <linux/writeback.h>
  12 #include <linux/pagevec.h>
  13 #include <linux/prefetch.h>
  14 #include <linux/cleancache.h>
  15 #include "extent_io.h"
  16 #include "extent_map.h"
  17 #include "ctree.h"
  18 #include "btrfs_inode.h"
  19 #include "volumes.h"
  20 #include "check-integrity.h"
  21 #include "locking.h"
  22 #include "rcu-string.h"
  23 #include "backref.h"
  24
  25 static struct kmem_cache *extent_state_cache;
  26 static struct kmem_cache *extent_buffer_cache;
  27 static struct bio_set *btrfs_bioset;
  28
  29 static inline bool extent_state_in_tree(const struct extent_state *state)
  30 {
  31         return !RB_EMPTY_NODE(&state->rb_node);
  32 }
  33
  34 #ifdef CONFIG_BTRFS_DEBUG
  35 static LIST_HEAD(buffers);
  36 static LIST_HEAD(states);
  37
  38 static DEFINE_SPINLOCK(leak_lock);
  39
  40 static inline
  41 void btrfs_leak_debug_add(struct list_head *new, struct list_head *head)
  42 {
  43         unsigned long flags;
  44
  45         spin_lock_irqsave(&leak_lock, flags);
  46         list_add(new, head);
  47         spin_unlock_irqrestore(&leak_lock, flags);
  48 }
  49
  50 static inline
  51 void btrfs_leak_debug_del(struct list_head *entry)
  52 {
  53         unsigned long flags;
  54
  55         spin_lock_irqsave(&leak_lock, flags);
  56         list_del(entry);
  57         spin_unlock_irqrestore(&leak_lock, flags);
  58 }
  59
  60 static inline
  61 void btrfs_leak_debug_check(void)
  62 {
  63         struct extent_state *state;
  64         struct extent_buffer *eb;
  65
  66         while (!list_empty(&states)) {
  67                 state = list_entry(states.next, struct extent_state, leak_list);
  68                 pr_err("BTRFS: state leak: start %llu end %llu state %u in tree %d refs %d\n",
  69                        state->start, state->end, state->state,
  70                        extent_state_in_tree(state),
  71                        refcount_read(&state->refs));
  72                 list_del(&state->leak_list);
  73                 kmem_cache_free(extent_state_cache, state);
  74         }
  75
  76         while (!list_empty(&buffers)) {
  77                 eb = list_entry(buffers.next, struct extent_buffer, leak_list);
  78                 pr_err("BTRFS: buffer leak start %llu len %lu 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         if (tree->ops && tree->ops->check_extent_io_range)
  91                 tree->ops->check_extent_io_range(tree->private_data, caller,
  92                                                  start, end);
  93 }
  94 #else
  95 #define btrfs_leak_debug_add(new, head) do {} while (0)
  96 #define btrfs_leak_debug_del(entry)     do {} while (0)
  97 #define btrfs_leak_debug_check()        do {} while (0)
  98 #define btrfs_debug_check_extent_io_range(c, s, e)      do {} while (0)
  99 #endif
 100
 101 #define BUFFER_LRU_MAX 64
 102
 103 struct tree_entry {
 104         u64 start;
 105         u64 end;
 106         struct rb_node rb_node;
 107 };
 108
 109 struct extent_page_data {
 110         struct bio *bio;
 111         struct extent_io_tree *tree;
 112         get_extent_t *get_extent;
 113         unsigned long bio_flags;
 114
 115         /* tells writepage not to lock the state bits for this range
 116          * it still does the unlocking
 117          */
 118         unsigned int extent_locked:1;
 119
 120         /* tells the submit_bio code to use REQ_SYNC */
 121         unsigned int sync_io:1;
 122 };
 123
 124 static void add_extent_changeset(struct extent_state *state, unsigned bits,
 125                                  struct extent_changeset *changeset,
 126                                  int set)
 127 {
 128         int ret;
 129
 130         if (!changeset)
 131                 return;
 132         if (set && (state->state & bits) == bits)
 133                 return;
 134         if (!set && (state->state & bits) == 0)
 135                 return;
 136         changeset->bytes_changed += state->end - state->start + 1;
 137         ret = ulist_add(&changeset->range_changed, state->start, state->end,
 138                         GFP_ATOMIC);
 139         /* ENOMEM */
 140         BUG_ON(ret < 0);
 141 }
 142
 143 static noinline void flush_write_bio(void *data);
 144 static inline struct btrfs_fs_info *
 145 tree_fs_info(struct extent_io_tree *tree)
 146 {
 147         if (tree->ops)
 148                 return tree->ops->tree_fs_info(tree->private_data);
 149         return NULL;
 150 }
 151
 152 int __init extent_io_init(void)
 153 {
 154         extent_state_cache = kmem_cache_create("btrfs_extent_state",
 155                         sizeof(struct extent_state), 0,
 156                         SLAB_MEM_SPREAD, NULL);
 157         if (!extent_state_cache)
 158                 return -ENOMEM;
 159
 160         extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
 161                         sizeof(struct extent_buffer), 0,
 162                         SLAB_MEM_SPREAD, NULL);
 163         if (!extent_buffer_cache)
 164                 goto free_state_cache;
 165
 166         btrfs_bioset = bioset_create(BIO_POOL_SIZE,
 167                                      offsetof(struct btrfs_io_bio, bio),
 168                                      BIOSET_NEED_BVECS);
 169         if (!btrfs_bioset)
 170                 goto free_buffer_cache;
 171
 172         if (bioset_integrity_create(btrfs_bioset, BIO_POOL_SIZE))
 173                 goto free_bioset;
 174
 175         return 0;
 176
 177 free_bioset:
 178         bioset_free(btrfs_bioset);
 179         btrfs_bioset = NULL;
 180
 181 free_buffer_cache:
 182         kmem_cache_destroy(extent_buffer_cache);
 183         extent_buffer_cache = NULL;
 184
 185 free_state_cache:
 186         kmem_cache_destroy(extent_state_cache);
 187         extent_state_cache = NULL;
 188         return -ENOMEM;
 189 }
 190
 191 void extent_io_exit(void)
 192 {
 193         btrfs_leak_debug_check();
 194
 195         /*
 196          * Make sure all delayed rcu free are flushed before we
 197          * destroy caches.
 198          */
 199         rcu_barrier();
 200         kmem_cache_destroy(extent_state_cache);
 201         kmem_cache_destroy(extent_buffer_cache);
 202         if (btrfs_bioset)
 203                 bioset_free(btrfs_bioset);
 204 }
 205
 206 void extent_io_tree_init(struct extent_io_tree *tree,
 207                          void *private_data)
 208 {
 209         tree->state = RB_ROOT;
 210         tree->ops = NULL;
 211         tree->dirty_bytes = 0;
 212         spin_lock_init(&tree->lock);
 213         tree->private_data = private_data;
 214 }
 215
 216 static struct extent_state *alloc_extent_state(gfp_t mask)
 217 {
 218         struct extent_state *state;
 219
 220         /*
 221          * The given mask might be not appropriate for the slab allocator,
 222          * drop the unsupported bits
 223          */
 224         mask &= ~(__GFP_DMA32|__GFP_HIGHMEM);
 225         state = kmem_cache_alloc(extent_state_cache, mask);
 226         if (!state)
 227                 return state;
 228         state->state = 0;
 229         state->failrec = NULL;
 230         RB_CLEAR_NODE(&state->rb_node);
 231         btrfs_leak_debug_add(&state->leak_list, &states);
 232         refcount_set(&state->refs, 1);
 233         init_waitqueue_head(&state->wq);
 234         trace_alloc_extent_state(state, mask, _RET_IP_);
 235         return state;
 236 }
 237
 238 void free_extent_state(struct extent_state *state)
 239 {
 240         if (!state)
 241                 return;
 242         if (refcount_dec_and_test(&state->refs)) {
 243                 WARN_ON(extent_state_in_tree(state));
 244                 btrfs_leak_debug_del(&state->leak_list);
 245                 trace_free_extent_state(state, _RET_IP_);
 246                 kmem_cache_free(extent_state_cache, state);
 247         }
 248 }
 249
 250 static struct rb_node *tree_insert(struct rb_root *root,
 251                                    struct rb_node *search_start,
 252                                    u64 offset,
 253                                    struct rb_node *node,
 254                                    struct rb_node ***p_in,
 255                                    struct rb_node **parent_in)
 256 {
 257         struct rb_node **p;
 258         struct rb_node *parent = NULL;
 259         struct tree_entry *entry;
 260
 261         if (p_in && parent_in) {
 262                 p = *p_in;
 263                 parent = *parent_in;
 264                 goto do_insert;
 265         }
 266
 267         p = search_start ? &search_start : &root->rb_node;
 268         while (*p) {
 269                 parent = *p;
 270                 entry = rb_entry(parent, struct tree_entry, rb_node);
 271
 272                 if (offset < entry->start)
 273                         p = &(*p)->rb_left;
 274                 else if (offset > entry->end)
 275                         p = &(*p)->rb_right;
 276                 else
 277                         return parent;
 278         }
 279
 280 do_insert:
 281         rb_link_node(node, parent, p);
 282         rb_insert_color(node, root);
 283         return NULL;
 284 }
 285
 286 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 287                                       struct rb_node **prev_ret,
 288                                       struct rb_node **next_ret,
 289                                       struct rb_node ***p_ret,
 290                                       struct rb_node **parent_ret)
 291 {
 292         struct rb_root *root = &tree->state;
 293         struct rb_node **n = &root->rb_node;
 294         struct rb_node *prev = NULL;
 295         struct rb_node *orig_prev = NULL;
 296         struct tree_entry *entry;
 297         struct tree_entry *prev_entry = NULL;
 298
 299         while (*n) {
 300                 prev = *n;
 301                 entry = rb_entry(prev, struct tree_entry, rb_node);
 302                 prev_entry = entry;
 303
 304                 if (offset < entry->start)
 305                         n = &(*n)->rb_left;
 306                 else if (offset > entry->end)
 307                         n = &(*n)->rb_right;
 308                 else
 309                         return *n;
 310         }
 311
 312         if (p_ret)
 313                 *p_ret = n;
 314         if (parent_ret)
 315                 *parent_ret = prev;
 316
 317         if (prev_ret) {
 318                 orig_prev = prev;
 319                 while (prev && offset > prev_entry->end) {
 320                         prev = rb_next(prev);
 321                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 322                 }
 323                 *prev_ret = prev;
 324                 prev = orig_prev;
 325         }
 326
 327         if (next_ret) {
 328                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 329                 while (prev && offset < prev_entry->start) {
 330                         prev = rb_prev(prev);
 331                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 332                 }
 333                 *next_ret = prev;
 334         }
 335         return NULL;
 336 }
 337
 338 static inline struct rb_node *
 339 tree_search_for_insert(struct extent_io_tree *tree,
 340                        u64 offset,
 341                        struct rb_node ***p_ret,
 342                        struct rb_node **parent_ret)
 343 {
 344         struct rb_node *prev = NULL;
 345         struct rb_node *ret;
 346
 347         ret = __etree_search(tree, offset, &prev, NULL, p_ret, parent_ret);
 348         if (!ret)
 349                 return prev;
 350         return ret;
 351 }
 352
 353 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 354                                           u64 offset)
 355 {
 356         return tree_search_for_insert(tree, offset, NULL, NULL);
 357 }
 358
 359 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
 360                      struct extent_state *other)
 361 {
 362         if (tree->ops && tree->ops->merge_extent_hook)
 363                 tree->ops->merge_extent_hook(tree->private_data, new, other);
 364 }
 365
 366 /*
 367  * utility function to look for merge candidates inside a given range.
 368  * Any extents with matching state are merged together into a single
 369  * extent in the tree.  Extents with EXTENT_IO in their state field
 370  * are not merged because the end_io handlers need to be able to do
 371  * operations on them without sleeping (or doing allocations/splits).
 372  *
 373  * This should be called with the tree lock held.
 374  */
 375 static void merge_state(struct extent_io_tree *tree,
 376                         struct extent_state *state)
 377 {
 378         struct extent_state *other;
 379         struct rb_node *other_node;
 380
 381         if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 382                 return;
 383
 384         other_node = rb_prev(&state->rb_node);
 385         if (other_node) {
 386                 other = rb_entry(other_node, struct extent_state, rb_node);
 387                 if (other->end == state->start - 1 &&
 388                     other->state == state->state) {
 389                         merge_cb(tree, state, other);
 390                         state->start = other->start;
 391                         rb_erase(&other->rb_node, &tree->state);
 392                         RB_CLEAR_NODE(&other->rb_node);
 393                         free_extent_state(other);
 394                 }
 395         }
 396         other_node = rb_next(&state->rb_node);
 397         if (other_node) {
 398                 other = rb_entry(other_node, struct extent_state, rb_node);
 399                 if (other->start == state->end + 1 &&
 400                     other->state == state->state) {
 401                         merge_cb(tree, state, other);
 402                         state->end = other->end;
 403                         rb_erase(&other->rb_node, &tree->state);
 404                         RB_CLEAR_NODE(&other->rb_node);
 405                         free_extent_state(other);
 406                 }
 407         }
 408 }
 409
 410 static void set_state_cb(struct extent_io_tree *tree,
 411                          struct extent_state *state, unsigned *bits)
 412 {
 413         if (tree->ops && tree->ops->set_bit_hook)
 414                 tree->ops->set_bit_hook(tree->private_data, state, bits);
 415 }
 416
 417 static void clear_state_cb(struct extent_io_tree *tree,
 418                            struct extent_state *state, unsigned *bits)
 419 {
 420         if (tree->ops && tree->ops->clear_bit_hook)
 421                 tree->ops->clear_bit_hook(tree->private_data, state, bits);
 422 }
 423
 424 static void set_state_bits(struct extent_io_tree *tree,
 425                            struct extent_state *state, unsigned *bits,
 426                            struct extent_changeset *changeset);
 427
 428 /*
 429  * insert an extent_state struct into the tree.  'bits' are set on the
 430  * struct before it is inserted.
 431  *
 432  * This may return -EEXIST if the extent is already there, in which case the
 433  * state struct is freed.
 434  *
 435  * The tree lock is not taken internally.  This is a utility function and
 436  * probably isn't what you want to call (see set/clear_extent_bit).
 437  */
 438 static int insert_state(struct extent_io_tree *tree,
 439                         struct extent_state *state, u64 start, u64 end,
 440                         struct rb_node ***p,
 441                         struct rb_node **parent,
 442                         unsigned *bits, struct extent_changeset *changeset)
 443 {
 444         struct rb_node *node;
 445
 446         if (end < start)
 447                 WARN(1, KERN_ERR "BTRFS: end < start %llu %llu\n",
 448                        end, start);
 449         state->start = start;
 450         state->end = end;
 451
 452         set_state_bits(tree, state, bits, changeset);
 453
 454         node = tree_insert(&tree->state, NULL, end, &state->rb_node, p, parent);
 455         if (node) {
 456                 struct extent_state *found;
 457                 found = rb_entry(node, struct extent_state, rb_node);
 458                 pr_err("BTRFS: found node %llu %llu on insert of %llu %llu\n",
 459                        found->start, found->end, start, end);
 460                 return -EEXIST;
 461         }
 462         merge_state(tree, state);
 463         return 0;
 464 }
 465
 466 static void split_cb(struct extent_io_tree *tree, struct extent_state *orig,
 467                      u64 split)
 468 {
 469         if (tree->ops && tree->ops->split_extent_hook)
 470                 tree->ops->split_extent_hook(tree->private_data, orig, split);
 471 }
 472
 473 /*
 474  * split a given extent state struct in two, inserting the preallocated
 475  * struct 'prealloc' as the newly created second half.  'split' indicates an
 476  * offset inside 'orig' where it should be split.
 477  *
 478  * Before calling,
 479  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
 480  * are two extent state structs in the tree:
 481  * prealloc: [orig->start, split - 1]
 482  * orig: [ split, orig->end ]
 483  *
 484  * The tree locks are not taken by this function. They need to be held
 485  * by the caller.
 486  */
 487 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 488                        struct extent_state *prealloc, u64 split)
 489 {
 490         struct rb_node *node;
 491
 492         split_cb(tree, orig, split);
 493
 494         prealloc->start = orig->start;
 495         prealloc->end = split - 1;
 496         prealloc->state = orig->state;
 497         orig->start = split;
 498
 499         node = tree_insert(&tree->state, &orig->rb_node, prealloc->end,
 500                            &prealloc->rb_node, NULL, NULL);
 501         if (node) {
 502                 free_extent_state(prealloc);
 503                 return -EEXIST;
 504         }
 505         return 0;
 506 }
 507
 508 static struct extent_state *next_state(struct extent_state *state)
 509 {
 510         struct rb_node *next = rb_next(&state->rb_node);
 511         if (next)
 512                 return rb_entry(next, struct extent_state, rb_node);
 513         else
 514                 return NULL;
 515 }
 516
 517 /*
 518  * utility function to clear some bits in an extent state struct.
 519  * it will optionally wake up any one waiting on this state (wake == 1).
 520  *
 521  * If no bits are set on the state struct after clearing things, the
 522  * struct is freed and removed from the tree
 523  */
 524 static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
 525                                             struct extent_state *state,
 526                                             unsigned *bits, int wake,
 527                                             struct extent_changeset *changeset)
 528 {
 529         struct extent_state *next;
 530         unsigned bits_to_clear = *bits & ~EXTENT_CTLBITS;
 531
 532         if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 533                 u64 range = state->end - state->start + 1;
 534                 WARN_ON(range > tree->dirty_bytes);
 535                 tree->dirty_bytes -= range;
 536         }
 537         clear_state_cb(tree, state, bits);
 538         add_extent_changeset(state, bits_to_clear, changeset, 0);
 539         state->state &= ~bits_to_clear;
 540         if (wake)
 541                 wake_up(&state->wq);
 542         if (state->state == 0) {
 543                 next = next_state(state);
 544                 if (extent_state_in_tree(state)) {
 545                         rb_erase(&state->rb_node, &tree->state);
 546                         RB_CLEAR_NODE(&state->rb_node);
 547                         free_extent_state(state);
 548                 } else {
 549                         WARN_ON(1);
 550                 }
 551         } else {
 552                 merge_state(tree, state);
 553                 next = next_state(state);
 554         }
 555         return next;
 556 }
 557
 558 static struct extent_state *
 559 alloc_extent_state_atomic(struct extent_state *prealloc)
 560 {
 561         if (!prealloc)
 562                 prealloc = alloc_extent_state(GFP_ATOMIC);
 563
 564         return prealloc;
 565 }
 566
 567 static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
 568 {
 569         btrfs_panic(tree_fs_info(tree), err,
 570                     "Locking error: Extent tree was modified by another thread while locked.");
 571 }
 572
 573 /*
 574  * clear some bits on a range in the tree.  This may require splitting
 575  * or inserting elements in the tree, so the gfp mask is used to
 576  * indicate which allocations or sleeping are allowed.
 577  *
 578  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 579  * the given range from the tree regardless of state (ie for truncate).
 580  *
 581  * the range [start, end] is inclusive.
 582  *
 583  * This takes the tree lock, and returns 0 on success and < 0 on error.
 584  */
 585 static int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 586                               unsigned bits, int wake, int delete,
 587                               struct extent_state **cached_state,
 588                               gfp_t mask, struct extent_changeset *changeset)
 589 {
 590         struct extent_state *state;
 591         struct extent_state *cached;
 592         struct extent_state *prealloc = NULL;
 593         struct rb_node *node;
 594         u64 last_end;
 595         int err;
 596         int clear = 0;
 597
 598         btrfs_debug_check_extent_io_range(tree, start, end);
 599
 600         if (bits & EXTENT_DELALLOC)
 601                 bits |= EXTENT_NORESERVE;
 602
 603         if (delete)
 604                 bits |= ~EXTENT_CTLBITS;
 605         bits |= EXTENT_FIRST_DELALLOC;
 606
 607         if (bits & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 608                 clear = 1;
 609 again:
 610         if (!prealloc && gfpflags_allow_blocking(mask)) {
 611                 /*
 612                  * Don't care for allocation failure here because we might end
 613                  * up not needing the pre-allocated extent state at all, which
 614                  * is the case if we only have in the tree extent states that
 615                  * cover our input range and don't cover too any other range.
 616                  * If we end up needing a new extent state we allocate it later.
 617                  */
 618                 prealloc = alloc_extent_state(mask);
 619         }
 620
 621         spin_lock(&tree->lock);
 622         if (cached_state) {
 623                 cached = *cached_state;
 624
 625                 if (clear) {
 626                         *cached_state = NULL;
 627                         cached_state = NULL;
 628                 }
 629
 630                 if (cached && extent_state_in_tree(cached) &&
 631                     cached->start <= start && cached->end > start) {
 632                         if (clear)
 633                                 refcount_dec(&cached->refs);
 634                         state = cached;
 635                         goto hit_next;
 636                 }
 637                 if (clear)
 638                         free_extent_state(cached);
 639         }
 640         /*
 641          * this search will find the extents that end after
 642          * our range starts
 643          */
 644         node = tree_search(tree, start);
 645         if (!node)
 646                 goto out;
 647         state = rb_entry(node, struct extent_state, rb_node);
 648 hit_next:
 649         if (state->start > end)
 650                 goto out;
 651         WARN_ON(state->end < start);
 652         last_end = state->end;
 653
 654         /* the state doesn't have the wanted bits, go ahead */
 655         if (!(state->state & bits)) {
 656                 state = next_state(state);
 657                 goto next;
 658         }
 659
 660         /*
 661          *     | ---- desired range ---- |
 662          *  | state | or
 663          *  | ------------- state -------------- |
 664          *
 665          * We need to split the extent we found, and may flip
 666          * bits on second half.
 667          *
 668          * If the extent we found extends past our range, we
 669          * just split and search again.  It'll get split again
 670          * the next time though.
 671          *
 672          * If the extent we found is inside our range, we clear
 673          * the desired bit on it.
 674          */
 675
 676         if (state->start < start) {
 677                 prealloc = alloc_extent_state_atomic(prealloc);
 678                 BUG_ON(!prealloc);
 679                 err = split_state(tree, state, prealloc, start);
 680                 if (err)
 681                         extent_io_tree_panic(tree, err);
 682
 683                 prealloc = NULL;
 684                 if (err)
 685                         goto out;
 686                 if (state->end <= end) {
 687                         state = clear_state_bit(tree, state, &bits, wake,
 688                                                 changeset);
 689                         goto next;
 690                 }
 691                 goto search_again;
 692         }
 693         /*
 694          * | ---- desired range ---- |
 695          *                        | state |
 696          * We need to split the extent, and clear the bit
 697          * on the first half
 698          */
 699         if (state->start <= end && state->end > end) {
 700                 prealloc = alloc_extent_state_atomic(prealloc);
 701                 BUG_ON(!prealloc);
 702                 err = split_state(tree, state, prealloc, end + 1);
 703                 if (err)
 704                         extent_io_tree_panic(tree, err);
 705
 706                 if (wake)
 707                         wake_up(&state->wq);
 708
 709                 clear_state_bit(tree, prealloc, &bits, wake, changeset);
 710
 711                 prealloc = NULL;
 712                 goto out;
 713         }
 714
 715         state = clear_state_bit(tree, state, &bits, wake, changeset);
 716 next:
 717         if (last_end == (u64)-1)
 718                 goto out;
 719         start = last_end + 1;
 720         if (start <= end && state && !need_resched())
 721                 goto hit_next;
 722
 723 search_again:
 724         if (start > end)
 725                 goto out;
 726         spin_unlock(&tree->lock);
 727         if (gfpflags_allow_blocking(mask))
 728                 cond_resched();
 729         goto again;
 730
 731 out:
 732         spin_unlock(&tree->lock);
 733         if (prealloc)
 734                 free_extent_state(prealloc);
 735
 736         return 0;
 737
 738 }
 739
 740 static void wait_on_state(struct extent_io_tree *tree,
 741                           struct extent_state *state)
 742                 __releases(tree->lock)
 743                 __acquires(tree->lock)
 744 {
 745         DEFINE_WAIT(wait);
 746         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 747         spin_unlock(&tree->lock);
 748         schedule();
 749         spin_lock(&tree->lock);
 750         finish_wait(&state->wq, &wait);
 751 }
 752
 753 /*
 754  * waits for one or more bits to clear on a range in the state tree.
 755  * The range [start, end] is inclusive.
 756  * The tree lock is taken by this function
 757  */
 758 static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 759                             unsigned long bits)
 760 {
 761         struct extent_state *state;
 762         struct rb_node *node;
 763
 764         btrfs_debug_check_extent_io_range(tree, start, end);
 765
 766         spin_lock(&tree->lock);
 767 again:
 768         while (1) {
 769                 /*
 770                  * this search will find all the extents that end after
 771                  * our range starts
 772                  */
 773                 node = tree_search(tree, start);
 774 process_node:
 775                 if (!node)
 776                         break;
 777
 778                 state = rb_entry(node, struct extent_state, rb_node);
 779
 780                 if (state->start > end)
 781                         goto out;
 782
 783                 if (state->state & bits) {
 784                         start = state->start;
 785                         refcount_inc(&state->refs);
 786                         wait_on_state(tree, state);
 787                         free_extent_state(state);
 788                         goto again;
 789                 }
 790                 start = state->end + 1;
 791
 792                 if (start > end)
 793                         break;
 794
 795                 if (!cond_resched_lock(&tree->lock)) {
 796                         node = rb_next(node);
 797                         goto process_node;
 798                 }
 799         }
 800 out:
 801         spin_unlock(&tree->lock);
 802 }
 803
 804 static void set_state_bits(struct extent_io_tree *tree,
 805                            struct extent_state *state,
 806                            unsigned *bits, struct extent_changeset *changeset)
 807 {
 808         unsigned bits_to_set = *bits & ~EXTENT_CTLBITS;
 809
 810         set_state_cb(tree, state, bits);
 811         if ((bits_to_set & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 812                 u64 range = state->end - state->start + 1;
 813                 tree->dirty_bytes += range;
 814         }
 815         add_extent_changeset(state, bits_to_set, changeset, 1);
 816         state->state |= bits_to_set;
 817 }
 818
 819 static void cache_state_if_flags(struct extent_state *state,
 820                                  struct extent_state **cached_ptr,
 821                                  unsigned flags)
 822 {
 823         if (cached_ptr && !(*cached_ptr)) {
 824                 if (!flags || (state->state & flags)) {
 825                         *cached_ptr = state;
 826                         refcount_inc(&state->refs);
 827                 }
 828         }
 829 }
 830
 831 static void cache_state(struct extent_state *state,
 832                         struct extent_state **cached_ptr)
 833 {
 834         return cache_state_if_flags(state, cached_ptr,
 835                                     EXTENT_IOBITS | EXTENT_BOUNDARY);
 836 }
 837
 838 /*
 839  * set some bits on a range in the tree.  This may require allocations or
 840  * sleeping, so the gfp mask is used to indicate what is allowed.
 841  *
 842  * If any of the exclusive bits are set, this will fail with -EEXIST if some
 843  * part of the range already has the desired bits set.  The start of the
 844  * existing range is returned in failed_start in this case.
 845  *
 846  * [start, end] is inclusive This takes the tree lock.
 847  */
 848
 849 static int __must_check
 850 __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 851                  unsigned bits, unsigned exclusive_bits,
 852                  u64 *failed_start, struct extent_state **cached_state,
 853                  gfp_t mask, struct extent_changeset *changeset)
 854 {
 855         struct extent_state *state;
 856         struct extent_state *prealloc = NULL;
 857         struct rb_node *node;
 858         struct rb_node **p;
 859         struct rb_node *parent;
 860         int err = 0;
 861         u64 last_start;
 862         u64 last_end;
 863
 864         btrfs_debug_check_extent_io_range(tree, start, end);
 865
 866         bits |= EXTENT_FIRST_DELALLOC;
 867 again:
 868         if (!prealloc && gfpflags_allow_blocking(mask)) {
 869                 /*
 870                  * Don't care for allocation failure here because we might end
 871                  * up not needing the pre-allocated extent state at all, which
 872                  * is the case if we only have in the tree extent states that
 873                  * cover our input range and don't cover too any other range.
 874                  * If we end up needing a new extent state we allocate it later.
 875                  */
 876                 prealloc = alloc_extent_state(mask);
 877         }
 878
 879         spin_lock(&tree->lock);
 880         if (cached_state && *cached_state) {
 881                 state = *cached_state;
 882                 if (state->start <= start && state->end > start &&
 883                     extent_state_in_tree(state)) {
 884                         node = &state->rb_node;
 885                         goto hit_next;
 886                 }
 887         }
 888         /*
 889          * this search will find all the extents that end after
 890          * our range starts.
 891          */
 892         node = tree_search_for_insert(tree, start, &p, &parent);
 893         if (!node) {
 894                 prealloc = alloc_extent_state_atomic(prealloc);
 895                 BUG_ON(!prealloc);
 896                 err = insert_state(tree, prealloc, start, end,
 897                                    &p, &parent, &bits, changeset);
 898                 if (err)
 899                         extent_io_tree_panic(tree, err);
 900
 901                 cache_state(prealloc, cached_state);
 902                 prealloc = NULL;
 903                 goto out;
 904         }
 905         state = rb_entry(node, struct extent_state, rb_node);
 906 hit_next:
 907         last_start = state->start;
 908         last_end = state->end;
 909
 910         /*
 911          * | ---- desired range ---- |
 912          * | state |
 913          *
 914          * Just lock what we found and keep going
 915          */
 916         if (state->start == start && state->end <= end) {
 917                 if (state->state & exclusive_bits) {
 918                         *failed_start = state->start;
 919                         err = -EEXIST;
 920                         goto out;
 921                 }
 922
 923                 set_state_bits(tree, state, &bits, changeset);
 924                 cache_state(state, cached_state);
 925                 merge_state(tree, state);
 926                 if (last_end == (u64)-1)
 927                         goto out;
 928                 start = last_end + 1;
 929                 state = next_state(state);
 930                 if (start < end && state && state->start == start &&
 931                     !need_resched())
 932                         goto hit_next;
 933                 goto search_again;
 934         }
 935
 936         /*
 937          *     | ---- desired range ---- |
 938          * | state |
 939          *   or
 940          * | ------------- state -------------- |
 941          *
 942          * We need to split the extent we found, and may flip bits on
 943          * second half.
 944          *
 945          * If the extent we found extends past our
 946          * range, we just split and search again.  It'll get split
 947          * again the next time though.
 948          *
 949          * If the extent we found is inside our range, we set the
 950          * desired bit on it.
 951          */
 952         if (state->start < start) {
 953                 if (state->state & exclusive_bits) {
 954                         *failed_start = start;
 955                         err = -EEXIST;
 956                         goto out;
 957                 }
 958
 959                 prealloc = alloc_extent_state_atomic(prealloc);
 960                 BUG_ON(!prealloc);
 961                 err = split_state(tree, state, prealloc, start);
 962                 if (err)
 963                         extent_io_tree_panic(tree, err);
 964
 965                 prealloc = NULL;
 966                 if (err)
 967                         goto out;
 968                 if (state->end <= end) {
 969                         set_state_bits(tree, state, &bits, changeset);
 970                         cache_state(state, cached_state);
 971                         merge_state(tree, state);
 972                         if (last_end == (u64)-1)
 973                                 goto out;
 974                         start = last_end + 1;
 975                         state = next_state(state);
 976                         if (start < end && state && state->start == start &&
 977                             !need_resched())
 978                                 goto hit_next;
 979                 }
 980                 goto search_again;
 981         }
 982         /*
 983          * | ---- desired range ---- |
 984          *     | state | or               | state |
 985          *
 986          * There's a hole, we need to insert something in it and
 987          * ignore the extent we found.
 988          */
 989         if (state->start > start) {
 990                 u64 this_end;
 991                 if (end < last_start)
 992                         this_end = end;
 993                 else
 994                         this_end = last_start - 1;
 995
 996                 prealloc = alloc_extent_state_atomic(prealloc);
 997                 BUG_ON(!prealloc);
 998
 999                 /*
1000                  * Avoid to free 'prealloc' if it can be merged with
1001                  * the later extent.
1002                  */
1003                 err = insert_state(tree, prealloc, start, this_end,
1004                                    NULL, NULL, &bits, changeset);
1005                 if (err)
1006                         extent_io_tree_panic(tree, err);
1007
1008                 cache_state(prealloc, cached_state);
1009                 prealloc = NULL;
1010                 start = this_end + 1;
1011                 goto search_again;
1012         }
1013         /*
1014          * | ---- desired range ---- |
1015          *                        | state |
1016          * We need to split the extent, and set the bit
1017          * on the first half
1018          */
1019         if (state->start <= end && state->end > end) {
1020                 if (state->state & exclusive_bits) {
1021                         *failed_start = start;
1022                         err = -EEXIST;
1023                         goto out;
1024                 }
1025
1026                 prealloc = alloc_extent_state_atomic(prealloc);
1027                 BUG_ON(!prealloc);
1028                 err = split_state(tree, state, prealloc, end + 1);
1029                 if (err)
1030                         extent_io_tree_panic(tree, err);
1031
1032                 set_state_bits(tree, prealloc, &bits, changeset);
1033                 cache_state(prealloc, cached_state);
1034                 merge_state(tree, prealloc);
1035                 prealloc = NULL;
1036                 goto out;
1037         }
1038
1039 search_again:
1040         if (start > end)
1041                 goto out;
1042         spin_unlock(&tree->lock);
1043         if (gfpflags_allow_blocking(mask))
1044                 cond_resched();
1045         goto again;
1046
1047 out:
1048         spin_unlock(&tree->lock);
1049         if (prealloc)
1050                 free_extent_state(prealloc);
1051
1052         return err;
1053
1054 }
1055
1056 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1057                    unsigned bits, u64 * failed_start,
1058                    struct extent_state **cached_state, gfp_t mask)
1059 {
1060         return __set_extent_bit(tree, start, end, bits, 0, failed_start,
1061                                 cached_state, mask, NULL);
1062 }
1063
1064
1065 /**
1066  * convert_extent_bit - convert all bits in a given range from one bit to
1067  *                      another
1068  * @tree:       the io tree to search
1069  * @start:      the start offset in bytes
1070  * @end:        the end offset in bytes (inclusive)
1071  * @bits:       the bits to set in this range
1072  * @clear_bits: the bits to clear in this range
1073  * @cached_state:       state that we're going to cache
1074  *
1075  * This will go through and set bits for the given range.  If any states exist
1076  * already in this range they are set with the given bit and cleared of the
1077  * clear_bits.  This is only meant to be used by things that are mergeable, ie
1078  * converting from say DELALLOC to DIRTY.  This is not meant to be used with
1079  * boundary bits like LOCK.
1080  *
1081  * All allocations are done with GFP_NOFS.
1082  */
1083 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1084                        unsigned bits, unsigned clear_bits,
1085                        struct extent_state **cached_state)
1086 {
1087         struct extent_state *state;
1088         struct extent_state *prealloc = NULL;
1089         struct rb_node *node;
1090         struct rb_node **p;
1091         struct rb_node *parent;
1092         int err = 0;
1093         u64 last_start;
1094         u64 last_end;
1095         bool first_iteration = true;
1096
1097         btrfs_debug_check_extent_io_range(tree, start, end);
1098
1099 again:
1100         if (!prealloc) {
1101                 /*
1102                  * Best effort, don't worry if extent state allocation fails
1103                  * here for the first iteration. We might have a cached state
1104                  * that matches exactly the target range, in which case no
1105                  * extent state allocations are needed. We'll only know this
1106                  * after locking the tree.
1107                  */
1108                 prealloc = alloc_extent_state(GFP_NOFS);
1109                 if (!prealloc && !first_iteration)
1110                         return -ENOMEM;
1111         }
1112
1113         spin_lock(&tree->lock);
1114         if (cached_state && *cached_state) {
1115                 state = *cached_state;
1116                 if (state->start <= start && state->end > start &&
1117                     extent_state_in_tree(state)) {
1118                         node = &state->rb_node;
1119                         goto hit_next;
1120                 }
1121         }
1122
1123         /*
1124          * this search will find all the extents that end after
1125          * our range starts.
1126          */
1127         node = tree_search_for_insert(tree, start, &p, &parent);
1128         if (!node) {
1129                 prealloc = alloc_extent_state_atomic(prealloc);
1130                 if (!prealloc) {
1131                         err = -ENOMEM;
1132                         goto out;
1133                 }
1134                 err = insert_state(tree, prealloc, start, end,
1135                                    &p, &parent, &bits, NULL);
1136                 if (err)
1137                         extent_io_tree_panic(tree, err);
1138                 cache_state(prealloc, cached_state);
1139                 prealloc = NULL;
1140                 goto out;
1141         }
1142         state = rb_entry(node, struct extent_state, rb_node);
1143 hit_next:
1144         last_start = state->start;
1145         last_end = state->end;
1146
1147         /*
1148          * | ---- desired range ---- |
1149          * | state |
1150          *
1151          * Just lock what we found and keep going
1152          */
1153         if (state->start == start && state->end <= end) {
1154                 set_state_bits(tree, state, &bits, NULL);
1155                 cache_state(state, cached_state);
1156                 state = clear_state_bit(tree, state, &clear_bits, 0, NULL);
1157                 if (last_end == (u64)-1)
1158                         goto out;
1159                 start = last_end + 1;
1160                 if (start < end && state && state->start == start &&
1161                     !need_resched())
1162                         goto hit_next;
1163                 goto search_again;
1164         }
1165
1166         /*
1167          *     | ---- desired range ---- |
1168          * | state |
1169          *   or
1170          * | ------------- state -------------- |
1171          *
1172          * We need to split the extent we found, and may flip bits on
1173          * second half.
1174          *
1175          * If the extent we found extends past our
1176          * range, we just split and search again.  It'll get split
1177          * again the next time though.
1178          *
1179          * If the extent we found is inside our range, we set the
1180          * desired bit on it.
1181          */
1182         if (state->start < start) {
1183                 prealloc = alloc_extent_state_atomic(prealloc);
1184                 if (!prealloc) {
1185                         err = -ENOMEM;
1186                         goto out;
1187                 }
1188                 err = split_state(tree, state, prealloc, start);
1189                 if (err)
1190                         extent_io_tree_panic(tree, err);
1191                 prealloc = NULL;
1192                 if (err)
1193                         goto out;
1194                 if (state->end <= end) {
1195                         set_state_bits(tree, state, &bits, NULL);
1196                         cache_state(state, cached_state);
1197                         state = clear_state_bit(tree, state, &clear_bits, 0,
1198                                                 NULL);
1199                         if (last_end == (u64)-1)
1200                                 goto out;
1201                         start = last_end + 1;
1202                         if (start < end && state && state->start == start &&
1203                             !need_resched())
1204                                 goto hit_next;
1205                 }
1206                 goto search_again;
1207         }
1208         /*
1209          * | ---- desired range ---- |
1210          *     | state | or               | state |
1211          *
1212          * There's a hole, we need to insert something in it and
1213          * ignore the extent we found.
1214          */
1215         if (state->start > start) {
1216                 u64 this_end;
1217                 if (end < last_start)
1218                         this_end = end;
1219                 else
1220                         this_end = last_start - 1;
1221
1222                 prealloc = alloc_extent_state_atomic(prealloc);
1223                 if (!prealloc) {
1224                         err = -ENOMEM;
1225                         goto out;
1226                 }
1227
1228                 /*
1229                  * Avoid to free 'prealloc' if it can be merged with
1230                  * the later extent.
1231                  */
1232                 err = insert_state(tree, prealloc, start, this_end,
1233                                    NULL, NULL, &bits, NULL);
1234                 if (err)
1235                         extent_io_tree_panic(tree, err);
1236                 cache_state(prealloc, cached_state);
1237                 prealloc = NULL;
1238                 start = this_end + 1;
1239                 goto search_again;
1240         }
1241         /*
1242          * | ---- desired range ---- |
1243          *                        | state |
1244          * We need to split the extent, and set the bit
1245          * on the first half
1246          */
1247         if (state->start <= end && state->end > end) {
1248                 prealloc = alloc_extent_state_atomic(prealloc);
1249                 if (!prealloc) {
1250                         err = -ENOMEM;
1251                         goto out;
1252                 }
1253
1254                 err = split_state(tree, state, prealloc, end + 1);
1255                 if (err)
1256                         extent_io_tree_panic(tree, err);
1257
1258                 set_state_bits(tree, prealloc, &bits, NULL);
1259                 cache_state(prealloc, cached_state);
1260                 clear_state_bit(tree, prealloc, &clear_bits, 0, NULL);
1261                 prealloc = NULL;
1262                 goto out;
1263         }
1264
1265 search_again:
1266         if (start > end)
1267                 goto out;
1268         spin_unlock(&tree->lock);
1269         cond_resched();
1270         first_iteration = false;
1271         goto again;
1272
1273 out:
1274         spin_unlock(&tree->lock);
1275         if (prealloc)
1276                 free_extent_state(prealloc);
1277
1278         return err;
1279 }
1280
1281 /* wrappers around set/clear extent bit */
1282 int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1283                            unsigned bits, struct extent_changeset *changeset)
1284 {
1285         /*
1286          * We don't support EXTENT_LOCKED yet, as current changeset will
1287          * record any bits changed, so for EXTENT_LOCKED case, it will
1288          * either fail with -EEXIST or changeset will record the whole
1289          * range.
1290          */
1291         BUG_ON(bits & EXTENT_LOCKED);
1292
1293         return __set_extent_bit(tree, start, end, bits, 0, NULL, NULL, GFP_NOFS,
1294                                 changeset);
1295 }
1296
1297 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1298                      unsigned bits, int wake, int delete,
1299                      struct extent_state **cached, gfp_t mask)
1300 {
1301         return __clear_extent_bit(tree, start, end, bits, wake, delete,
1302                                   cached, mask, NULL);
1303 }
1304
1305 int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1306                 unsigned bits, struct extent_changeset *changeset)
1307 {
1308         /*
1309          * Don't support EXTENT_LOCKED case, same reason as
1310          * set_record_extent_bits().
1311          */
1312         BUG_ON(bits & EXTENT_LOCKED);
1313
1314         return __clear_extent_bit(tree, start, end, bits, 0, 0, NULL, GFP_NOFS,
1315                                   changeset);
1316 }
1317
1318 /*
1319  * either insert or lock state struct between start and end use mask to tell
1320  * us if waiting is desired.
1321  */
1322 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1323                      struct extent_state **cached_state)
1324 {
1325         int err;
1326         u64 failed_start;
1327
1328         while (1) {
1329                 err = __set_extent_bit(tree, start, end, EXTENT_LOCKED,
1330                                        EXTENT_LOCKED, &failed_start,
1331                                        cached_state, GFP_NOFS, NULL);
1332                 if (err == -EEXIST) {
1333                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1334                         start = failed_start;
1335                 } else
1336                         break;
1337                 WARN_ON(start > end);
1338         }
1339         return err;
1340 }
1341
1342 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1343 {
1344         int err;
1345         u64 failed_start;
1346
1347         err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1348                                &failed_start, NULL, GFP_NOFS, NULL);
1349         if (err == -EEXIST) {
1350                 if (failed_start > start)
1351                         clear_extent_bit(tree, start, failed_start - 1,
1352                                          EXTENT_LOCKED, 1, 0, NULL, GFP_NOFS);
1353                 return 0;
1354         }
1355         return 1;
1356 }
1357
1358 void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
1359 {
1360         unsigned long index = start >> PAGE_SHIFT;
1361         unsigned long end_index = end >> PAGE_SHIFT;
1362         struct page *page;
1363
1364         while (index <= end_index) {
1365                 page = find_get_page(inode->i_mapping, index);
1366                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1367                 clear_page_dirty_for_io(page);
1368                 put_page(page);
1369                 index++;
1370         }
1371 }
1372
1373 void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
1374 {
1375         unsigned long index = start >> PAGE_SHIFT;
1376         unsigned long end_index = end >> PAGE_SHIFT;
1377         struct page *page;
1378
1379         while (index <= end_index) {
1380                 page = find_get_page(inode->i_mapping, index);
1381                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1382                 __set_page_dirty_nobuffers(page);
1383                 account_page_redirty(page);
1384                 put_page(page);
1385                 index++;
1386         }
1387 }
1388
1389 /*
1390  * helper function to set both pages and extents in the tree writeback
1391  */
1392 static void set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1393 {
1394         tree->ops->set_range_writeback(tree->private_data, start, end);
1395 }
1396
1397 /* find the first state struct with 'bits' set after 'start', and
1398  * return it.  tree->lock must be held.  NULL will returned if
1399  * nothing was found after 'start'
1400  */
1401 static struct extent_state *
1402 find_first_extent_bit_state(struct extent_io_tree *tree,
1403                             u64 start, unsigned bits)
1404 {
1405         struct rb_node *node;
1406         struct extent_state *state;
1407
1408         /*
1409          * this search will find all the extents that end after
1410          * our range starts.
1411          */
1412         node = tree_search(tree, start);
1413         if (!node)
1414                 goto out;
1415
1416         while (1) {
1417                 state = rb_entry(node, struct extent_state, rb_node);
1418                 if (state->end >= start && (state->state & bits))
1419                         return state;
1420
1421                 node = rb_next(node);
1422                 if (!node)
1423                         break;
1424         }
1425 out:
1426         return NULL;
1427 }
1428
1429 /*
1430  * find the first offset in the io tree with 'bits' set. zero is
1431  * returned if we find something, and *start_ret and *end_ret are
1432  * set to reflect the state struct that was found.
1433  *
1434  * If nothing was found, 1 is returned. If found something, return 0.
1435  */
1436 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1437                           u64 *start_ret, u64 *end_ret, unsigned bits,
1438                           struct extent_state **cached_state)
1439 {
1440         struct extent_state *state;
1441         struct rb_node *n;
1442         int ret = 1;
1443
1444         spin_lock(&tree->lock);
1445         if (cached_state && *cached_state) {
1446                 state = *cached_state;
1447                 if (state->end == start - 1 && extent_state_in_tree(state)) {
1448                         n = rb_next(&state->rb_node);
1449                         while (n) {
1450                                 state = rb_entry(n, struct extent_state,
1451                                                  rb_node);
1452                                 if (state->state & bits)
1453                                         goto got_it;
1454                                 n = rb_next(n);
1455                         }
1456                         free_extent_state(*cached_state);
1457                         *cached_state = NULL;
1458                         goto out;
1459                 }
1460                 free_extent_state(*cached_state);
1461                 *cached_state = NULL;
1462         }
1463
1464         state = find_first_extent_bit_state(tree, start, bits);
1465 got_it:
1466         if (state) {
1467                 cache_state_if_flags(state, cached_state, 0);
1468                 *start_ret = state->start;
1469                 *end_ret = state->end;
1470                 ret = 0;
1471         }
1472 out:
1473         spin_unlock(&tree->lock);
1474         return ret;
1475 }
1476
1477 /*
1478  * find a contiguous range of bytes in the file marked as delalloc, not
1479  * more than 'max_bytes'.  start and end are used to return the range,
1480  *
1481  * 1 is returned if we find something, 0 if nothing was in the tree
1482  */
1483 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1484                                         u64 *start, u64 *end, u64 max_bytes,
1485                                         struct extent_state **cached_state)
1486 {
1487         struct rb_node *node;
1488         struct extent_state *state;
1489         u64 cur_start = *start;
1490         u64 found = 0;
1491         u64 total_bytes = 0;
1492
1493         spin_lock(&tree->lock);
1494
1495         /*
1496          * this search will find all the extents that end after
1497          * our range starts.
1498          */
1499         node = tree_search(tree, cur_start);
1500         if (!node) {
1501                 if (!found)
1502                         *end = (u64)-1;
1503                 goto out;
1504         }
1505
1506         while (1) {
1507                 state = rb_entry(node, struct extent_state, rb_node);
1508                 if (found && (state->start != cur_start ||
1509                               (state->state & EXTENT_BOUNDARY))) {
1510                         goto out;
1511                 }
1512                 if (!(state->state & EXTENT_DELALLOC)) {
1513                         if (!found)
1514                                 *end = state->end;
1515                         goto out;
1516                 }
1517                 if (!found) {
1518                         *start = state->start;
1519                         *cached_state = state;
1520                         refcount_inc(&state->refs);
1521                 }
1522                 found++;
1523                 *end = state->end;
1524                 cur_start = state->end + 1;
1525                 node = rb_next(node);
1526                 total_bytes += state->end - state->start + 1;
1527                 if (total_bytes >= max_bytes)
1528                         break;
1529                 if (!node)
1530                         break;
1531         }
1532 out:
1533         spin_unlock(&tree->lock);
1534         return found;
1535 }
1536
1537 static int __process_pages_contig(struct address_space *mapping,
1538                                   struct page *locked_page,
1539                                   pgoff_t start_index, pgoff_t end_index,
1540                                   unsigned long page_ops, pgoff_t *index_ret);
1541
1542 static noinline void __unlock_for_delalloc(struct inode *inode,
1543                                            struct page *locked_page,
1544                                            u64 start, u64 end)
1545 {
1546         unsigned long index = start >> PAGE_SHIFT;
1547         unsigned long end_index = end >> PAGE_SHIFT;
1548
1549         ASSERT(locked_page);
1550         if (index == locked_page->index && end_index == index)
1551                 return;
1552
1553         __process_pages_contig(inode->i_mapping, locked_page, index, end_index,
1554                                PAGE_UNLOCK, NULL);
1555 }
1556
1557 static noinline int lock_delalloc_pages(struct inode *inode,
1558                                         struct page *locked_page,
1559                                         u64 delalloc_start,
1560                                         u64 delalloc_end)
1561 {
1562         unsigned long index = delalloc_start >> PAGE_SHIFT;
1563         unsigned long index_ret = index;
1564         unsigned long end_index = delalloc_end >> PAGE_SHIFT;
1565         int ret;
1566
1567         ASSERT(locked_page);
1568         if (index == locked_page->index && index == end_index)
1569                 return 0;
1570
1571         ret = __process_pages_contig(inode->i_mapping, locked_page, index,
1572                                      end_index, PAGE_LOCK, &index_ret);
1573         if (ret == -EAGAIN)
1574                 __unlock_for_delalloc(inode, locked_page, delalloc_start,
1575                                       (u64)index_ret << PAGE_SHIFT);
1576         return ret;
1577 }
1578
1579 /*
1580  * find a contiguous range of bytes in the file marked as delalloc, not
1581  * more than 'max_bytes'.  start and end are used to return the range,
1582  *
1583  * 1 is returned if we find something, 0 if nothing was in the tree
1584  */
1585 STATIC u64 find_lock_delalloc_range(struct inode *inode,
1586                                     struct extent_io_tree *tree,
1587                                     struct page *locked_page, u64 *start,
1588                                     u64 *end, u64 max_bytes)
1589 {
1590         u64 delalloc_start;
1591         u64 delalloc_end;
1592         u64 found;
1593         struct extent_state *cached_state = NULL;
1594         int ret;
1595         int loops = 0;
1596
1597 again:
1598         /* step one, find a bunch of delalloc bytes starting at start */
1599         delalloc_start = *start;
1600         delalloc_end = 0;
1601         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1602                                     max_bytes, &cached_state);
1603         if (!found || delalloc_end <= *start) {
1604                 *start = delalloc_start;
1605                 *end = delalloc_end;
1606                 free_extent_state(cached_state);
1607                 return 0;
1608         }
1609
1610         /*
1611          * start comes from the offset of locked_page.  We have to lock
1612          * pages in order, so we can't process delalloc bytes before
1613          * locked_page
1614          */
1615         if (delalloc_start < *start)
1616                 delalloc_start = *start;
1617
1618         /*
1619          * make sure to limit the number of pages we try to lock down
1620          */
1621         if (delalloc_end + 1 - delalloc_start > max_bytes)
1622                 delalloc_end = delalloc_start + max_bytes - 1;
1623
1624         /* step two, lock all the pages after the page that has start */
1625         ret = lock_delalloc_pages(inode, locked_page,
1626                                   delalloc_start, delalloc_end);
1627         if (ret == -EAGAIN) {
1628                 /* some of the pages are gone, lets avoid looping by
1629                  * shortening the size of the delalloc range we're searching
1630                  */
1631                 free_extent_state(cached_state);
1632                 cached_state = NULL;
1633                 if (!loops) {
1634                         max_bytes = PAGE_SIZE;
1635                         loops = 1;
1636                         goto again;
1637                 } else {
1638                         found = 0;
1639                         goto out_failed;
1640                 }
1641         }
1642         BUG_ON(ret); /* Only valid values are 0 and -EAGAIN */
1643
1644         /* step three, lock the state bits for the whole range */
1645         lock_extent_bits(tree, delalloc_start, delalloc_end, &cached_state);
1646
1647         /* then test to make sure it is all still delalloc */
1648         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1649                              EXTENT_DELALLOC, 1, cached_state);
1650         if (!ret) {
1651                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1652                                      &cached_state, GFP_NOFS);
1653                 __unlock_for_delalloc(inode, locked_page,
1654                               delalloc_start, delalloc_end);
1655                 cond_resched();
1656                 goto again;
1657         }
1658         free_extent_state(cached_state);
1659         *start = delalloc_start;
1660         *end = delalloc_end;
1661 out_failed:
1662         return found;
1663 }
1664
1665 static int __process_pages_contig(struct address_space *mapping,
1666                                   struct page *locked_page,
1667                                   pgoff_t start_index, pgoff_t end_index,
1668                                   unsigned long page_ops, pgoff_t *index_ret)
1669 {
1670         unsigned long nr_pages = end_index - start_index + 1;
1671         unsigned long pages_locked = 0;
1672         pgoff_t index = start_index;
1673         struct page *pages[16];
1674         unsigned ret;
1675         int err = 0;
1676         int i;
1677
1678         if (page_ops & PAGE_LOCK) {
1679                 ASSERT(page_ops == PAGE_LOCK);
1680                 ASSERT(index_ret && *index_ret == start_index);
1681         }
1682
1683         if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
1684                 mapping_set_error(mapping, -EIO);
1685
1686         while (nr_pages > 0) {
1687                 ret = find_get_pages_contig(mapping, index,
1688                                      min_t(unsigned long,
1689                                      nr_pages, ARRAY_SIZE(pages)), pages);
1690                 if (ret == 0) {
1691                         /*
1692                          * Only if we're going to lock these pages,
1693                          * can we find nothing at @index.
1694                          */
1695                         ASSERT(page_ops & PAGE_LOCK);
1696                         err = -EAGAIN;
1697                         goto out;
1698                 }
1699
1700                 for (i = 0; i < ret; i++) {
1701                         if (page_ops & PAGE_SET_PRIVATE2)
1702                                 SetPagePrivate2(pages[i]);
1703
1704                         if (pages[i] == locked_page) {
1705                                 put_page(pages[i]);
1706                                 pages_locked++;
1707                                 continue;
1708                         }
1709                         if (page_ops & PAGE_CLEAR_DIRTY)
1710                                 clear_page_dirty_for_io(pages[i]);
1711                         if (page_ops & PAGE_SET_WRITEBACK)
1712                                 set_page_writeback(pages[i]);
1713                         if (page_ops & PAGE_SET_ERROR)
1714                                 SetPageError(pages[i]);
1715                         if (page_ops & PAGE_END_WRITEBACK)
1716                                 end_page_writeback(pages[i]);
1717                         if (page_ops & PAGE_UNLOCK)
1718                                 unlock_page(pages[i]);
1719                         if (page_ops & PAGE_LOCK) {
1720                                 lock_page(pages[i]);
1721                                 if (!PageDirty(pages[i]) ||
1722                                     pages[i]->mapping != mapping) {
1723                                         unlock_page(pages[i]);
1724                                         put_page(pages[i]);
1725                                         err = -EAGAIN;
1726                                         goto out;
1727                                 }
1728                         }
1729                         put_page(pages[i]);
1730                         pages_locked++;
1731                 }
1732                 nr_pages -= ret;
1733                 index += ret;
1734                 cond_resched();
1735         }
1736 out:
1737         if (err && index_ret)
1738                 *index_ret = start_index + pages_locked - 1;
1739         return err;
1740 }
1741
1742 void extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
1743                                  u64 delalloc_end, struct page *locked_page,
1744                                  unsigned clear_bits,
1745                                  unsigned long page_ops)
1746 {
1747         clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, clear_bits, 1, 0,
1748                          NULL, GFP_NOFS);
1749
1750         __process_pages_contig(inode->i_mapping, locked_page,
1751                                start >> PAGE_SHIFT, end >> PAGE_SHIFT,
1752                                page_ops, NULL);
1753 }
1754
1755 /*
1756  * count the number of bytes in the tree that have a given bit(s)
1757  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1758  * cached.  The total number found is returned.
1759  */
1760 u64 count_range_bits(struct extent_io_tree *tree,
1761                      u64 *start, u64 search_end, u64 max_bytes,
1762                      unsigned bits, int contig)
1763 {
1764         struct rb_node *node;
1765         struct extent_state *state;
1766         u64 cur_start = *start;
1767         u64 total_bytes = 0;
1768         u64 last = 0;
1769         int found = 0;
1770
1771         if (WARN_ON(search_end <= cur_start))
1772                 return 0;
1773
1774         spin_lock(&tree->lock);
1775         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1776                 total_bytes = tree->dirty_bytes;
1777                 goto out;
1778         }
1779         /*
1780          * this search will find all the extents that end after
1781          * our range starts.
1782          */
1783         node = tree_search(tree, cur_start);
1784         if (!node)
1785                 goto out;
1786
1787         while (1) {
1788                 state = rb_entry(node, struct extent_state, rb_node);
1789                 if (state->start > search_end)
1790                         break;
1791                 if (contig && found && state->start > last + 1)
1792                         break;
1793                 if (state->end >= cur_start && (state->state & bits) == bits) {
1794                         total_bytes += min(search_end, state->end) + 1 -
1795                                        max(cur_start, state->start);
1796                         if (total_bytes >= max_bytes)
1797                                 break;
1798                         if (!found) {
1799                                 *start = max(cur_start, state->start);
1800                                 found = 1;
1801                         }
1802                         last = state->end;
1803                 } else if (contig && found) {
1804                         break;
1805                 }
1806                 node = rb_next(node);
1807                 if (!node)
1808                         break;
1809         }
1810 out:
1811         spin_unlock(&tree->lock);
1812         return total_bytes;
1813 }
1814
1815 /*
1816  * set the private field for a given byte offset in the tree.  If there isn't
1817  * an extent_state there already, this does nothing.
1818  */
1819 static noinline int set_state_failrec(struct extent_io_tree *tree, u64 start,
1820                 struct io_failure_record *failrec)
1821 {
1822         struct rb_node *node;
1823         struct extent_state *state;
1824         int ret = 0;
1825
1826         spin_lock(&tree->lock);
1827         /*
1828          * this search will find all the extents that end after
1829          * our range starts.
1830          */
1831         node = tree_search(tree, start);
1832         if (!node) {
1833                 ret = -ENOENT;
1834                 goto out;
1835         }
1836         state = rb_entry(node, struct extent_state, rb_node);
1837         if (state->start != start) {
1838                 ret = -ENOENT;
1839                 goto out;
1840         }
1841         state->failrec = failrec;
1842 out:
1843         spin_unlock(&tree->lock);
1844         return ret;
1845 }
1846
1847 static noinline int get_state_failrec(struct extent_io_tree *tree, u64 start,
1848                 struct io_failure_record **failrec)
1849 {
1850         struct rb_node *node;
1851         struct extent_state *state;
1852         int ret = 0;
1853
1854         spin_lock(&tree->lock);
1855         /*
1856          * this search will find all the extents that end after
1857          * our range starts.
1858          */
1859         node = tree_search(tree, start);
1860         if (!node) {
1861                 ret = -ENOENT;
1862                 goto out;
1863         }
1864         state = rb_entry(node, struct extent_state, rb_node);
1865         if (state->start != start) {
1866                 ret = -ENOENT;
1867                 goto out;
1868         }
1869         *failrec = state->failrec;
1870 out:
1871         spin_unlock(&tree->lock);
1872         return ret;
1873 }
1874
1875 /*
1876  * searches a range in the state tree for a given mask.
1877  * If 'filled' == 1, this returns 1 only if every extent in the tree
1878  * has the bits set.  Otherwise, 1 is returned if any bit in the
1879  * range is found set.
1880  */
1881 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1882                    unsigned bits, int filled, struct extent_state *cached)
1883 {
1884         struct extent_state *state = NULL;
1885         struct rb_node *node;
1886         int bitset = 0;
1887
1888         spin_lock(&tree->lock);
1889         if (cached && extent_state_in_tree(cached) && cached->start <= start &&
1890             cached->end > start)
1891                 node = &cached->rb_node;
1892         else
1893                 node = tree_search(tree, start);
1894         while (node && start <= end) {
1895                 state = rb_entry(node, struct extent_state, rb_node);
1896
1897                 if (filled && state->start > start) {
1898                         bitset = 0;
1899                         break;
1900                 }
1901
1902                 if (state->start > end)
1903                         break;
1904
1905                 if (state->state & bits) {
1906                         bitset = 1;
1907                         if (!filled)
1908                                 break;
1909                 } else if (filled) {
1910                         bitset = 0;
1911                         break;
1912                 }
1913
1914                 if (state->end == (u64)-1)
1915                         break;
1916
1917                 start = state->end + 1;
1918                 if (start > end)
1919                         break;
1920                 node = rb_next(node);
1921                 if (!node) {
1922                         if (filled)
1923                                 bitset = 0;
1924                         break;
1925                 }
1926         }
1927         spin_unlock(&tree->lock);
1928         return bitset;
1929 }
1930
1931 /*
1932  * helper function to set a given page up to date if all the
1933  * extents in the tree for that page are up to date
1934  */
1935 static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
1936 {
1937         u64 start = page_offset(page);
1938         u64 end = start + PAGE_SIZE - 1;
1939         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
1940                 SetPageUptodate(page);
1941 }
1942
1943 int free_io_failure(struct extent_io_tree *failure_tree,
1944                     struct extent_io_tree *io_tree,
1945                     struct io_failure_record *rec)
1946 {
1947         int ret;
1948         int err = 0;
1949
1950         set_state_failrec(failure_tree, rec->start, NULL);
1951         ret = clear_extent_bits(failure_tree, rec->start,
1952                                 rec->start + rec->len - 1,
1953                                 EXTENT_LOCKED | EXTENT_DIRTY);
1954         if (ret)
1955                 err = ret;
1956
1957         ret = clear_extent_bits(io_tree, rec->start,
1958                                 rec->start + rec->len - 1,
1959                                 EXTENT_DAMAGED);
1960         if (ret && !err)
1961                 err = ret;
1962
1963         kfree(rec);
1964         return err;
1965 }
1966
1967 /*
1968  * this bypasses the standard btrfs submit functions deliberately, as
1969  * the standard behavior is to write all copies in a raid setup. here we only
1970  * want to write the one bad copy. so we do the mapping for ourselves and issue
1971  * submit_bio directly.
1972  * to avoid any synchronization issues, wait for the data after writing, which
1973  * actually prevents the read that triggered the error from finishing.
1974  * currently, there can be no more than two copies of every data bit. thus,
1975  * exactly one rewrite is required.
1976  */
1977 int repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
1978                       u64 length, u64 logical, struct page *page,
1979                       unsigned int pg_offset, int mirror_num)
1980 {
1981         struct bio *bio;
1982         struct btrfs_device *dev;
1983         u64 map_length = 0;
1984         u64 sector;
1985         struct btrfs_bio *bbio = NULL;
1986         int ret;
1987
1988         ASSERT(!(fs_info->sb->s_flags & MS_RDONLY));
1989         BUG_ON(!mirror_num);
1990
1991         bio = btrfs_io_bio_alloc(1);
1992         bio->bi_iter.bi_size = 0;
1993         map_length = length;
1994
1995         /*
1996          * Avoid races with device replace and make sure our bbio has devices
1997          * associated to its stripes that don't go away while we are doing the
1998          * read repair operation.
1999          */
2000         btrfs_bio_counter_inc_blocked(fs_info);
2001         if (btrfs_is_parity_mirror(fs_info, logical, length)) {
2002                 /*
2003                  * Note that we don't use BTRFS_MAP_WRITE because it's supposed
2004                  * to update all raid stripes, but here we just want to correct
2005                  * bad stripe, thus BTRFS_MAP_READ is abused to only get the bad
2006                  * stripe's dev and sector.
2007                  */
2008                 ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, logical,
2009                                       &map_length, &bbio, 0);
2010                 if (ret) {
2011                         btrfs_bio_counter_dec(fs_info);
2012                         bio_put(bio);
2013                         return -EIO;
2014                 }
2015                 ASSERT(bbio->mirror_num == 1);
2016         } else {
2017                 ret = btrfs_map_block(fs_info, BTRFS_MAP_WRITE, logical,
2018                                       &map_length, &bbio, mirror_num);
2019                 if (ret) {
2020                         btrfs_bio_counter_dec(fs_info);
2021                         bio_put(bio);
2022                         return -EIO;
2023                 }
2024                 BUG_ON(mirror_num != bbio->mirror_num);
2025         }
2026
2027         sector = bbio->stripes[bbio->mirror_num - 1].physical >> 9;
2028         bio->bi_iter.bi_sector = sector;
2029         dev = bbio->stripes[bbio->mirror_num - 1].dev;
2030         btrfs_put_bbio(bbio);
2031         if (!dev || !dev->bdev || !dev->writeable) {
2032                 btrfs_bio_counter_dec(fs_info);
2033                 bio_put(bio);
2034                 return -EIO;
2035         }
2036         bio_set_dev(bio, dev->bdev);
2037         bio->bi_opf = REQ_OP_WRITE | REQ_SYNC;
2038         bio_add_page(bio, page, length, pg_offset);
2039
2040         if (btrfsic_submit_bio_wait(bio)) {
2041                 /* try to remap that extent elsewhere? */
2042                 btrfs_bio_counter_dec(fs_info);
2043                 bio_put(bio);
2044                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
2045                 return -EIO;
2046         }
2047
2048         btrfs_info_rl_in_rcu(fs_info,
2049                 "read error corrected: ino %llu off %llu (dev %s sector %llu)",
2050                                   ino, start,
2051                                   rcu_str_deref(dev->name), sector);
2052         btrfs_bio_counter_dec(fs_info);
2053         bio_put(bio);
2054         return 0;
2055 }
2056
2057 int repair_eb_io_failure(struct btrfs_fs_info *fs_info,
2058                          struct extent_buffer *eb, int mirror_num)
2059 {
2060         u64 start = eb->start;
2061         unsigned long i, num_pages = num_extent_pages(eb->start, eb->len);
2062         int ret = 0;
2063
2064         if (sb_rdonly(fs_info->sb))
2065                 return -EROFS;
2066
2067         for (i = 0; i < num_pages; i++) {
2068                 struct page *p = eb->pages[i];
2069
2070                 ret = repair_io_failure(fs_info, 0, start, PAGE_SIZE, start, p,
2071                                         start - page_offset(p), mirror_num);
2072                 if (ret)
2073                         break;
2074                 start += PAGE_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 btrfs_fs_info *fs_info,
2085                      struct extent_io_tree *failure_tree,
2086                      struct extent_io_tree *io_tree, u64 start,
2087                      struct page *page, u64 ino, unsigned int pg_offset)
2088 {
2089         u64 private;
2090         struct io_failure_record *failrec;
2091         struct extent_state *state;
2092         int num_copies;
2093         int ret;
2094
2095         private = 0;
2096         ret = count_range_bits(failure_tree, &private, (u64)-1, 1,
2097                                EXTENT_DIRTY, 0);
2098         if (!ret)
2099                 return 0;
2100
2101         ret = get_state_failrec(failure_tree, start, &failrec);
2102         if (ret)
2103                 return 0;
2104
2105         BUG_ON(!failrec->this_mirror);
2106
2107         if (failrec->in_validation) {
2108                 /* there was no real error, just free the record */
2109                 btrfs_debug(fs_info,
2110                         "clean_io_failure: freeing dummy error at %llu",
2111                         failrec->start);
2112                 goto out;
2113         }
2114         if (sb_rdonly(fs_info->sb))
2115                 goto out;
2116
2117         spin_lock(&io_tree->lock);
2118         state = find_first_extent_bit_state(io_tree,
2119                                             failrec->start,
2120                                             EXTENT_LOCKED);
2121         spin_unlock(&io_tree->lock);
2122
2123         if (state && state->start <= failrec->start &&
2124             state->end >= failrec->start + failrec->len - 1) {
2125                 num_copies = btrfs_num_copies(fs_info, failrec->logical,
2126                                               failrec->len);
2127                 if (num_copies > 1)  {
2128                         repair_io_failure(fs_info, ino, start, failrec->len,
2129                                           failrec->logical, page, pg_offset,
2130                                           failrec->failed_mirror);
2131                 }
2132         }
2133
2134 out:
2135         free_io_failure(failure_tree, io_tree, failrec);
2136
2137         return 0;
2138 }
2139
2140 /*
2141  * Can be called when
2142  * - hold extent lock
2143  * - under ordered extent
2144  * - the inode is freeing
2145  */
2146 void btrfs_free_io_failure_record(struct btrfs_inode *inode, u64 start, u64 end)
2147 {
2148         struct extent_io_tree *failure_tree = &inode->io_failure_tree;
2149         struct io_failure_record *failrec;
2150         struct extent_state *state, *next;
2151
2152         if (RB_EMPTY_ROOT(&failure_tree->state))
2153                 return;
2154
2155         spin_lock(&failure_tree->lock);
2156         state = find_first_extent_bit_state(failure_tree, start, EXTENT_DIRTY);
2157         while (state) {
2158                 if (state->start > end)
2159                         break;
2160
2161                 ASSERT(state->end <= end);
2162
2163                 next = next_state(state);
2164
2165                 failrec = state->failrec;
2166                 free_extent_state(state);
2167                 kfree(failrec);
2168
2169                 state = next;
2170         }
2171         spin_unlock(&failure_tree->lock);
2172 }
2173
2174 int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
2175                 struct io_failure_record **failrec_ret)
2176 {
2177         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2178         struct io_failure_record *failrec;
2179         struct extent_map *em;
2180         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2181         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2182         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2183         int ret;
2184         u64 logical;
2185
2186         ret = get_state_failrec(failure_tree, start, &failrec);
2187         if (ret) {
2188                 failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
2189                 if (!failrec)
2190                         return -ENOMEM;
2191
2192                 failrec->start = start;
2193                 failrec->len = end - start + 1;
2194                 failrec->this_mirror = 0;
2195                 failrec->bio_flags = 0;
2196                 failrec->in_validation = 0;
2197
2198                 read_lock(&em_tree->lock);
2199                 em = lookup_extent_mapping(em_tree, start, failrec->len);
2200                 if (!em) {
2201                         read_unlock(&em_tree->lock);
2202                         kfree(failrec);
2203                         return -EIO;
2204                 }
2205
2206                 if (em->start > start || em->start + em->len <= start) {
2207                         free_extent_map(em);
2208                         em = NULL;
2209                 }
2210                 read_unlock(&em_tree->lock);
2211                 if (!em) {
2212                         kfree(failrec);
2213                         return -EIO;
2214                 }
2215
2216                 logical = start - em->start;
2217                 logical = em->block_start + logical;
2218                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2219                         logical = em->block_start;
2220                         failrec->bio_flags = EXTENT_BIO_COMPRESSED;
2221                         extent_set_compress_type(&failrec->bio_flags,
2222                                                  em->compress_type);
2223                 }
2224
2225                 btrfs_debug(fs_info,
2226                         "Get IO Failure Record: (new) logical=%llu, start=%llu, len=%llu",
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);
2235                 if (ret >= 0)
2236                         ret = set_state_failrec(failure_tree, start, failrec);
2237                 /* set the bits in the inode's tree */
2238                 if (ret >= 0)
2239                         ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED);
2240                 if (ret < 0) {
2241                         kfree(failrec);
2242                         return ret;
2243                 }
2244         } else {
2245                 btrfs_debug(fs_info,
2246                         "Get IO Failure Record: (found) logical=%llu, start=%llu, len=%llu, validation=%d",
2247                         failrec->logical, failrec->start, failrec->len,
2248                         failrec->in_validation);
2249                 /*
2250                  * when data can be on disk more than twice, add to failrec here
2251                  * (e.g. with a list for failed_mirror) to make
2252                  * clean_io_failure() clean all those errors at once.
2253                  */
2254         }
2255
2256         *failrec_ret = failrec;
2257
2258         return 0;
2259 }
2260
2261 bool btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
2262                            struct io_failure_record *failrec, int failed_mirror)
2263 {
2264         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2265         int num_copies;
2266
2267         num_copies = btrfs_num_copies(fs_info, failrec->logical, failrec->len);
2268         if (num_copies == 1) {
2269                 /*
2270                  * we only have a single copy of the data, so don't bother with
2271                  * all the retry and error correction code that follows. no
2272                  * matter what the error is, it is very likely to persist.
2273                  */
2274                 btrfs_debug(fs_info,
2275                         "Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d",
2276                         num_copies, failrec->this_mirror, failed_mirror);
2277                 return false;
2278         }
2279
2280         /*
2281          * there are two premises:
2282          *      a) deliver good data to the caller
2283          *      b) correct the bad sectors on disk
2284          */
2285         if (failed_bio->bi_vcnt > 1) {
2286                 /*
2287                  * to fulfill b), we need to know the exact failing sectors, as
2288                  * we don't want to rewrite any more than the failed ones. thus,
2289                  * we need separate read requests for the failed bio
2290                  *
2291                  * if the following BUG_ON triggers, our validation request got
2292                  * merged. we need separate requests for our algorithm to work.
2293                  */
2294                 BUG_ON(failrec->in_validation);
2295                 failrec->in_validation = 1;
2296                 failrec->this_mirror = failed_mirror;
2297         } else {
2298                 /*
2299                  * we're ready to fulfill a) and b) alongside. get a good copy
2300                  * of the failed sector and if we succeed, we have setup
2301                  * everything for repair_io_failure to do the rest for us.
2302                  */
2303                 if (failrec->in_validation) {
2304                         BUG_ON(failrec->this_mirror != failed_mirror);
2305                         failrec->in_validation = 0;
2306                         failrec->this_mirror = 0;
2307                 }
2308                 failrec->failed_mirror = failed_mirror;
2309                 failrec->this_mirror++;
2310                 if (failrec->this_mirror == failed_mirror)
2311                         failrec->this_mirror++;
2312         }
2313
2314         if (failrec->this_mirror > num_copies) {
2315                 btrfs_debug(fs_info,
2316                         "Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d",
2317                         num_copies, failrec->this_mirror, failed_mirror);
2318                 return false;
2319         }
2320
2321         return true;
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 btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2331         struct bio *bio;
2332         struct btrfs_io_bio *btrfs_failed_bio;
2333         struct btrfs_io_bio *btrfs_bio;
2334
2335         bio = btrfs_io_bio_alloc(1);
2336         bio->bi_end_io = endio_func;
2337         bio->bi_iter.bi_sector = failrec->logical >> 9;
2338         bio_set_dev(bio, fs_info->fs_devices->latest_bdev);
2339         bio->bi_iter.bi_size = 0;
2340         bio->bi_private = data;
2341
2342         btrfs_failed_bio = btrfs_io_bio(failed_bio);
2343         if (btrfs_failed_bio->csum) {
2344                 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
2345
2346                 btrfs_bio = btrfs_io_bio(bio);
2347                 btrfs_bio->csum = btrfs_bio->csum_inline;
2348                 icsum *= csum_size;
2349                 memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + icsum,
2350                        csum_size);
2351         }
2352
2353         bio_add_page(bio, page, failrec->len, pg_offset);
2354
2355         return bio;
2356 }
2357
2358 /*
2359  * this is a generic handler for readpage errors (default
2360  * readpage_io_failed_hook). if other copies exist, read those and write back
2361  * good data to the failed position. does not investigate in remapping the
2362  * failed extent elsewhere, hoping the device will be smart enough to do this as
2363  * needed
2364  */
2365
2366 static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
2367                               struct page *page, u64 start, u64 end,
2368                               int failed_mirror)
2369 {
2370         struct io_failure_record *failrec;
2371         struct inode *inode = page->mapping->host;
2372         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2373         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2374         struct bio *bio;
2375         int read_mode = 0;
2376         blk_status_t status;
2377         int ret;
2378
2379         BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);
2380
2381         ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
2382         if (ret)
2383                 return ret;
2384
2385         if (!btrfs_check_repairable(inode, failed_bio, failrec,
2386                                     failed_mirror)) {
2387                 free_io_failure(failure_tree, tree, failrec);
2388                 return -EIO;
2389         }
2390
2391         if (failed_bio->bi_vcnt > 1)
2392                 read_mode |= REQ_FAILFAST_DEV;
2393
2394         phy_offset >>= inode->i_sb->s_blocksize_bits;
2395         bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
2396                                       start - page_offset(page),
2397                                       (int)phy_offset, failed_bio->bi_end_io,
2398                                       NULL);
2399         bio_set_op_attrs(bio, REQ_OP_READ, read_mode);
2400
2401         btrfs_debug(btrfs_sb(inode->i_sb),
2402                 "Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d",
2403                 read_mode, failrec->this_mirror, failrec->in_validation);
2404
2405         status = tree->ops->submit_bio_hook(tree->private_data, bio, failrec->this_mirror,
2406                                          failrec->bio_flags, 0);
2407         if (status) {
2408                 free_io_failure(failure_tree, tree, failrec);
2409                 bio_put(bio);
2410                 ret = blk_status_to_errno(status);
2411         }
2412
2413         return ret;
2414 }
2415
2416 /* lots and lots of room for performance fixes in the end_bio funcs */
2417
2418 void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
2419 {
2420         int uptodate = (err == 0);
2421         struct extent_io_tree *tree;
2422         int ret = 0;
2423
2424         tree = &BTRFS_I(page->mapping->host)->io_tree;
2425
2426         if (tree->ops && tree->ops->writepage_end_io_hook)
2427                 tree->ops->writepage_end_io_hook(page, start, end, NULL,
2428                                 uptodate);
2429
2430         if (!uptodate) {
2431                 ClearPageUptodate(page);
2432                 SetPageError(page);
2433                 ret = err < 0 ? err : -EIO;
2434                 mapping_set_error(page->mapping, ret);
2435         }
2436 }
2437
2438 /*
2439  * after a writepage IO is done, we need to:
2440  * clear the uptodate bits on error
2441  * clear the writeback bits in the extent tree for this IO
2442  * end_page_writeback if the page has no more pending IO
2443  *
2444  * Scheduling is not allowed, so the extent state tree is expected
2445  * to have one and only one object corresponding to this IO.
2446  */
2447 static void end_bio_extent_writepage(struct bio *bio)
2448 {
2449         int error = blk_status_to_errno(bio->bi_status);
2450         struct bio_vec *bvec;
2451         u64 start;
2452         u64 end;
2453         int i;
2454
2455         ASSERT(!bio_flagged(bio, BIO_CLONED));
2456         bio_for_each_segment_all(bvec, bio, i) {
2457                 struct page *page = bvec->bv_page;
2458                 struct inode *inode = page->mapping->host;
2459                 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2460
2461                 /* We always issue full-page reads, but if some block
2462                  * in a page fails to read, blk_update_request() will
2463                  * advance bv_offset and adjust bv_len to compensate.
2464                  * Print a warning for nonzero offsets, and an error
2465                  * if they don't add up to a full page.  */
2466                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2467                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2468                                 btrfs_err(fs_info,
2469                                    "partial page write in btrfs with offset %u and length %u",
2470                                         bvec->bv_offset, bvec->bv_len);
2471                         else
2472                                 btrfs_info(fs_info,
2473                                    "incomplete page write in btrfs with offset %u and length %u",
2474                                         bvec->bv_offset, bvec->bv_len);
2475                 }
2476
2477                 start = page_offset(page);
2478                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2479
2480                 end_extent_writepage(page, error, start, end);
2481                 end_page_writeback(page);
2482         }
2483
2484         bio_put(bio);
2485 }
2486
2487 static void
2488 endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
2489                               int uptodate)
2490 {
2491         struct extent_state *cached = NULL;
2492         u64 end = start + len - 1;
2493
2494         if (uptodate && tree->track_uptodate)
2495                 set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
2496         unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
2497 }
2498
2499 /*
2500  * after a readpage IO is done, we need to:
2501  * clear the uptodate bits on error
2502  * set the uptodate bits if things worked
2503  * set the page up to date if all extents in the tree are uptodate
2504  * clear the lock bit in the extent tree
2505  * unlock the page if there are no other extents locked for it
2506  *
2507  * Scheduling is not allowed, so the extent state tree is expected
2508  * to have one and only one object corresponding to this IO.
2509  */
2510 static void end_bio_extent_readpage(struct bio *bio)
2511 {
2512         struct bio_vec *bvec;
2513         int uptodate = !bio->bi_status;
2514         struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
2515         struct extent_io_tree *tree, *failure_tree;
2516         u64 offset = 0;
2517         u64 start;
2518         u64 end;
2519         u64 len;
2520         u64 extent_start = 0;
2521         u64 extent_len = 0;
2522         int mirror;
2523         int ret;
2524         int i;
2525
2526         ASSERT(!bio_flagged(bio, BIO_CLONED));
2527         bio_for_each_segment_all(bvec, bio, i) {
2528                 struct page *page = bvec->bv_page;
2529                 struct inode *inode = page->mapping->host;
2530                 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2531
2532                 btrfs_debug(fs_info,
2533                         "end_bio_extent_readpage: bi_sector=%llu, err=%d, mirror=%u",
2534                         (u64)bio->bi_iter.bi_sector, bio->bi_status,
2535                         io_bio->mirror_num);
2536                 tree = &BTRFS_I(inode)->io_tree;
2537                 failure_tree = &BTRFS_I(inode)->io_failure_tree;
2538
2539                 /* We always issue full-page reads, but if some block
2540                  * in a page fails to read, blk_update_request() will
2541                  * advance bv_offset and adjust bv_len to compensate.
2542                  * Print a warning for nonzero offsets, and an error
2543                  * if they don't add up to a full page.  */
2544                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2545                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2546                                 btrfs_err(fs_info,
2547                                         "partial page read in btrfs with offset %u and length %u",
2548                                         bvec->bv_offset, bvec->bv_len);
2549                         else
2550                                 btrfs_info(fs_info,
2551                                         "incomplete page read in btrfs with offset %u and length %u",
2552                                         bvec->bv_offset, bvec->bv_len);
2553                 }
2554
2555                 start = page_offset(page);
2556                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2557                 len = bvec->bv_len;
2558
2559                 mirror = io_bio->mirror_num;
2560                 if (likely(uptodate && tree->ops)) {
2561                         ret = tree->ops->readpage_end_io_hook(io_bio, offset,
2562                                                               page, start, end,
2563                                                               mirror);
2564                         if (ret)
2565                                 uptodate = 0;
2566                         else
2567                                 clean_io_failure(BTRFS_I(inode)->root->fs_info,
2568                                                  failure_tree, tree, start,
2569                                                  page,
2570                                                  btrfs_ino(BTRFS_I(inode)), 0);
2571                 }
2572
2573                 if (likely(uptodate))
2574                         goto readpage_ok;
2575
2576                 if (tree->ops) {
2577                         ret = tree->ops->readpage_io_failed_hook(page, mirror);
2578                         if (ret == -EAGAIN) {
2579                                 /*
2580                                  * Data inode's readpage_io_failed_hook() always
2581                                  * returns -EAGAIN.
2582                                  *
2583                                  * The generic bio_readpage_error handles errors
2584                                  * the following way: If possible, new read
2585                                  * requests are created and submitted and will
2586                                  * end up in end_bio_extent_readpage as well (if
2587                                  * we're lucky, not in the !uptodate case). In
2588                                  * that case it returns 0 and we just go on with
2589                                  * the next page in our bio. If it can't handle
2590                                  * the error it will return -EIO and we remain
2591                                  * responsible for that page.
2592                                  */
2593                                 ret = bio_readpage_error(bio, offset, page,
2594                                                          start, end, mirror);
2595                                 if (ret == 0) {
2596                                         uptodate = !bio->bi_status;
2597                                         offset += len;
2598                                         continue;
2599                                 }
2600                         }
2601
2602                         /*
2603                          * metadata's readpage_io_failed_hook() always returns
2604                          * -EIO and fixes nothing.  -EIO is also returned if
2605                          * data inode error could not be fixed.
2606                          */
2607                         ASSERT(ret == -EIO);
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_SHIFT;
2613                         unsigned off;
2614
2615                         /* Zero out the end if this page straddles i_size */
2616                         off = i_size & (PAGE_SIZE-1);
2617                         if (page->index == end_index && off)
2618                                 zero_user_segment(page, off, PAGE_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, blk_status_to_errno(bio->bi_status));
2655         bio_put(bio);
2656 }
2657
2658 /*
2659  * Initialize the members up to but not including 'bio'. Use after allocating a
2660  * new bio by bio_alloc_bioset as it does not initialize the bytes outside of
2661  * 'bio' because use of __GFP_ZERO is not supported.
2662  */
2663 static inline void btrfs_io_bio_init(struct btrfs_io_bio *btrfs_bio)
2664 {
2665         memset(btrfs_bio, 0, offsetof(struct btrfs_io_bio, bio));
2666 }
2667
2668 /*
2669  * The following helpers allocate a bio. As it's backed by a bioset, it'll
2670  * never fail.  We're returning a bio right now but you can call btrfs_io_bio
2671  * for the appropriate container_of magic
2672  */
2673 struct bio *btrfs_bio_alloc(struct block_device *bdev, u64 first_byte)
2674 {
2675         struct bio *bio;
2676
2677         bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, btrfs_bioset);
2678         bio_set_dev(bio, bdev);
2679         bio->bi_iter.bi_sector = first_byte >> 9;
2680         btrfs_io_bio_init(btrfs_io_bio(bio));
2681         return bio;
2682 }
2683
2684 struct bio *btrfs_bio_clone(struct bio *bio)
2685 {
2686         struct btrfs_io_bio *btrfs_bio;
2687         struct bio *new;
2688
2689         /* Bio allocation backed by a bioset does not fail */
2690         new = bio_clone_fast(bio, GFP_NOFS, btrfs_bioset);
2691         btrfs_bio = btrfs_io_bio(new);
2692         btrfs_io_bio_init(btrfs_bio);
2693         btrfs_bio->iter = bio->bi_iter;
2694         return new;
2695 }
2696
2697 struct bio *btrfs_io_bio_alloc(unsigned int nr_iovecs)
2698 {
2699         struct bio *bio;
2700
2701         /* Bio allocation backed by a bioset does not fail */
2702         bio = bio_alloc_bioset(GFP_NOFS, nr_iovecs, btrfs_bioset);
2703         btrfs_io_bio_init(btrfs_io_bio(bio));
2704         return bio;
2705 }
2706
2707 struct bio *btrfs_bio_clone_partial(struct bio *orig, int offset, int size)
2708 {
2709         struct bio *bio;
2710         struct btrfs_io_bio *btrfs_bio;
2711
2712         /* this will never fail when it's backed by a bioset */
2713         bio = bio_clone_fast(orig, GFP_NOFS, btrfs_bioset);
2714         ASSERT(bio);
2715
2716         btrfs_bio = btrfs_io_bio(bio);
2717         btrfs_io_bio_init(btrfs_bio);
2718
2719         bio_trim(bio, offset >> 9, size >> 9);
2720         btrfs_bio->iter = bio->bi_iter;
2721         return bio;
2722 }
2723
2724 static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
2725                                        unsigned long bio_flags)
2726 {
2727         blk_status_t ret = 0;
2728         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
2729         struct page *page = bvec->bv_page;
2730         struct extent_io_tree *tree = bio->bi_private;
2731         u64 start;
2732
2733         start = page_offset(page) + bvec->bv_offset;
2734
2735         bio->bi_private = NULL;
2736         bio_get(bio);
2737
2738         if (tree->ops)
2739                 ret = tree->ops->submit_bio_hook(tree->private_data, bio,
2740                                            mirror_num, bio_flags, start);
2741         else
2742                 btrfsic_submit_bio(bio);
2743
2744         bio_put(bio);
2745         return blk_status_to_errno(ret);
2746 }
2747
2748 static int merge_bio(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)
2754                 ret = tree->ops->merge_bio_hook(page, offset, size, bio,
2755                                                 bio_flags);
2756         return ret;
2757
2758 }
2759
2760 /*
2761  * @opf:        bio REQ_OP_* and REQ_* flags as one value
2762  */
2763 static int submit_extent_page(unsigned int opf, struct extent_io_tree *tree,
2764                               struct writeback_control *wbc,
2765                               struct page *page, sector_t sector,
2766                               size_t size, unsigned long offset,
2767                               struct block_device *bdev,
2768                               struct bio **bio_ret,
2769                               bio_end_io_t end_io_func,
2770                               int mirror_num,
2771                               unsigned long prev_bio_flags,
2772                               unsigned long bio_flags,
2773                               bool force_bio_submit)
2774 {
2775         int ret = 0;
2776         struct bio *bio;
2777         int contig = 0;
2778         int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
2779         size_t page_size = min_t(size_t, size, PAGE_SIZE);
2780
2781         if (bio_ret && *bio_ret) {
2782                 bio = *bio_ret;
2783                 if (old_compressed)
2784                         contig = bio->bi_iter.bi_sector == sector;
2785                 else
2786                         contig = bio_end_sector(bio) == sector;
2787
2788                 if (prev_bio_flags != bio_flags || !contig ||
2789                     force_bio_submit ||
2790                     merge_bio(tree, page, offset, page_size, bio, bio_flags) ||
2791                     bio_add_page(bio, page, page_size, offset) < page_size) {
2792                         ret = submit_one_bio(bio, mirror_num, prev_bio_flags);
2793                         if (ret < 0) {
2794                                 *bio_ret = NULL;
2795                                 return ret;
2796                         }
2797                         bio = NULL;
2798                 } else {
2799                         if (wbc)
2800                                 wbc_account_io(wbc, page, page_size);
2801                         return 0;
2802                 }
2803         }
2804
2805         bio = btrfs_bio_alloc(bdev, (u64)sector << 9);
2806         bio_add_page(bio, page, page_size, offset);
2807         bio->bi_end_io = end_io_func;
2808         bio->bi_private = tree;
2809         bio->bi_write_hint = page->mapping->host->i_write_hint;
2810         bio->bi_opf = opf;
2811         if (wbc) {
2812                 wbc_init_bio(wbc, bio);
2813                 wbc_account_io(wbc, page, page_size);
2814         }
2815
2816         if (bio_ret)
2817                 *bio_ret = bio;
2818         else
2819                 ret = submit_one_bio(bio, mirror_num, bio_flags);
2820
2821         return ret;
2822 }
2823
2824 static void attach_extent_buffer_page(struct extent_buffer *eb,
2825                                       struct page *page)
2826 {
2827         if (!PagePrivate(page)) {
2828                 SetPagePrivate(page);
2829                 get_page(page);
2830                 set_page_private(page, (unsigned long)eb);
2831         } else {
2832                 WARN_ON(page->private != (unsigned long)eb);
2833         }
2834 }
2835
2836 void set_page_extent_mapped(struct page *page)
2837 {
2838         if (!PagePrivate(page)) {
2839                 SetPagePrivate(page);
2840                 get_page(page);
2841                 set_page_private(page, EXTENT_PAGE_PRIVATE);
2842         }
2843 }
2844
2845 static struct extent_map *
2846 __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
2847                  u64 start, u64 len, get_extent_t *get_extent,
2848                  struct extent_map **em_cached)
2849 {
2850         struct extent_map *em;
2851
2852         if (em_cached && *em_cached) {
2853                 em = *em_cached;
2854                 if (extent_map_in_tree(em) && start >= em->start &&
2855                     start < extent_map_end(em)) {
2856                         refcount_inc(&em->refs);
2857                         return em;
2858                 }
2859
2860                 free_extent_map(em);
2861                 *em_cached = NULL;
2862         }
2863
2864         em = get_extent(BTRFS_I(inode), page, pg_offset, start, len, 0);
2865         if (em_cached && !IS_ERR_OR_NULL(em)) {
2866                 BUG_ON(*em_cached);
2867                 refcount_inc(&em->refs);
2868                 *em_cached = em;
2869         }
2870         return em;
2871 }
2872 /*
2873  * basic readpage implementation.  Locked extent state structs are inserted
2874  * into the tree that are removed when the IO is done (by the end_io
2875  * handlers)
2876  * XXX JDM: This needs looking at to ensure proper page locking
2877  * return 0 on success, otherwise return error
2878  */
2879 static int __do_readpage(struct extent_io_tree *tree,
2880                          struct page *page,
2881                          get_extent_t *get_extent,
2882                          struct extent_map **em_cached,
2883                          struct bio **bio, int mirror_num,
2884                          unsigned long *bio_flags, unsigned int read_flags,
2885                          u64 *prev_em_start)
2886 {
2887         struct inode *inode = page->mapping->host;
2888         u64 start = page_offset(page);
2889         u64 page_end = start + PAGE_SIZE - 1;
2890         u64 end;
2891         u64 cur = start;
2892         u64 extent_offset;
2893         u64 last_byte = i_size_read(inode);
2894         u64 block_start;
2895         u64 cur_end;
2896         sector_t sector;
2897         struct extent_map *em;
2898         struct block_device *bdev;
2899         int ret = 0;
2900         int nr = 0;
2901         size_t pg_offset = 0;
2902         size_t iosize;
2903         size_t disk_io_size;
2904         size_t blocksize = inode->i_sb->s_blocksize;
2905         unsigned long this_bio_flag = 0;
2906
2907         set_page_extent_mapped(page);
2908
2909         end = page_end;
2910         if (!PageUptodate(page)) {
2911                 if (cleancache_get_page(page) == 0) {
2912                         BUG_ON(blocksize != PAGE_SIZE);
2913                         unlock_extent(tree, start, end);
2914                         goto out;
2915                 }
2916         }
2917
2918         if (page->index == last_byte >> PAGE_SHIFT) {
2919                 char *userpage;
2920                 size_t zero_offset = last_byte & (PAGE_SIZE - 1);
2921
2922                 if (zero_offset) {
2923                         iosize = PAGE_SIZE - zero_offset;
2924                         userpage = kmap_atomic(page);
2925                         memset(userpage + zero_offset, 0, iosize);
2926                         flush_dcache_page(page);
2927                         kunmap_atomic(userpage);
2928                 }
2929         }
2930         while (cur <= end) {
2931                 bool force_bio_submit = false;
2932
2933                 if (cur >= last_byte) {
2934                         char *userpage;
2935                         struct extent_state *cached = NULL;
2936
2937                         iosize = PAGE_SIZE - pg_offset;
2938                         userpage = kmap_atomic(page);
2939                         memset(userpage + pg_offset, 0, iosize);
2940                         flush_dcache_page(page);
2941                         kunmap_atomic(userpage);
2942                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2943                                             &cached, GFP_NOFS);
2944                         unlock_extent_cached(tree, cur,
2945                                              cur + iosize - 1,
2946                                              &cached, GFP_NOFS);
2947                         break;
2948                 }
2949                 em = __get_extent_map(inode, page, pg_offset, cur,
2950                                       end - cur + 1, get_extent, em_cached);
2951                 if (IS_ERR_OR_NULL(em)) {
2952                         SetPageError(page);
2953                         unlock_extent(tree, cur, end);
2954                         break;
2955                 }
2956                 extent_offset = cur - em->start;
2957                 BUG_ON(extent_map_end(em) <= cur);
2958                 BUG_ON(end < cur);
2959
2960                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2961                         this_bio_flag |= EXTENT_BIO_COMPRESSED;
2962                         extent_set_compress_type(&this_bio_flag,
2963                                                  em->compress_type);
2964                 }
2965
2966                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2967                 cur_end = min(extent_map_end(em) - 1, end);
2968                 iosize = ALIGN(iosize, blocksize);
2969                 if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
2970                         disk_io_size = em->block_len;
2971                         sector = em->block_start >> 9;
2972                 } else {
2973                         sector = (em->block_start + extent_offset) >> 9;
2974                         disk_io_size = iosize;
2975                 }
2976                 bdev = em->bdev;
2977                 block_start = em->block_start;
2978                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2979                         block_start = EXTENT_MAP_HOLE;
2980
2981                 /*
2982                  * If we have a file range that points to a compressed extent
2983                  * and it's followed by a consecutive file range that points to
2984                  * to the same compressed extent (possibly with a different
2985                  * offset and/or length, so it either points to the whole extent
2986                  * or only part of it), we must make sure we do not submit a
2987                  * single bio to populate the pages for the 2 ranges because
2988                  * this makes the compressed extent read zero out the pages
2989                  * belonging to the 2nd range. Imagine the following scenario:
2990                  *
2991                  *  File layout
2992                  *  [0 - 8K]                     [8K - 24K]
2993                  *    |                               |
2994                  *    |                               |
2995                  * points to extent X,         points to extent X,
2996                  * offset 4K, length of 8K     offset 0, length 16K
2997                  *
2998                  * [extent X, compressed length = 4K uncompressed length = 16K]
2999                  *
3000                  * If the bio to read the compressed extent covers both ranges,
3001                  * it will decompress extent X into the pages belonging to the
3002                  * first range and then it will stop, zeroing out the remaining
3003                  * pages that belong to the other range that points to extent X.
3004                  * So here we make sure we submit 2 bios, one for the first
3005                  * range and another one for the third range. Both will target
3006                  * the same physical extent from disk, but we can't currently
3007                  * make the compressed bio endio callback populate the pages
3008                  * for both ranges because each compressed bio is tightly
3009                  * coupled with a single extent map, and each range can have
3010                  * an extent map with a different offset value relative to the
3011                  * uncompressed data of our extent and different lengths. This
3012                  * is a corner case so we prioritize correctness over
3013                  * non-optimal behavior (submitting 2 bios for the same extent).
3014                  */
3015                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) &&
3016                     prev_em_start && *prev_em_start != (u64)-1 &&
3017                     *prev_em_start != em->orig_start)
3018                         force_bio_submit = true;
3019
3020                 if (prev_em_start)
3021                         *prev_em_start = em->orig_start;
3022
3023                 free_extent_map(em);
3024                 em = NULL;
3025
3026                 /* we've found a hole, just zero and go on */
3027                 if (block_start == EXTENT_MAP_HOLE) {
3028                         char *userpage;
3029                         struct extent_state *cached = NULL;
3030
3031                         userpage = kmap_atomic(page);
3032                         memset(userpage + pg_offset, 0, iosize);
3033                         flush_dcache_page(page);
3034                         kunmap_atomic(userpage);
3035
3036                         set_extent_uptodate(tree, cur, cur + iosize - 1,
3037                                             &cached, GFP_NOFS);
3038                         unlock_extent_cached(tree, cur,
3039                                              cur + iosize - 1,
3040                                              &cached, GFP_NOFS);
3041                         cur = cur + iosize;
3042                         pg_offset += iosize;
3043                         continue;
3044                 }
3045                 /* the get_extent function already copied into the page */
3046                 if (test_range_bit(tree, cur, cur_end,
3047                                    EXTENT_UPTODATE, 1, NULL)) {
3048                         check_page_uptodate(tree, page);
3049                         unlock_extent(tree, cur, cur + iosize - 1);
3050                         cur = cur + iosize;
3051                         pg_offset += iosize;
3052                         continue;
3053                 }
3054                 /* we have an inline extent but it didn't get marked up
3055                  * to date.  Error out
3056                  */
3057                 if (block_start == EXTENT_MAP_INLINE) {
3058                         SetPageError(page);
3059                         unlock_extent(tree, cur, cur + iosize - 1);
3060                         cur = cur + iosize;
3061                         pg_offset += iosize;
3062                         continue;
3063                 }
3064
3065                 ret = submit_extent_page(REQ_OP_READ | read_flags, tree, NULL,
3066                                          page, sector, disk_io_size, pg_offset,
3067                                          bdev, bio,
3068                                          end_bio_extent_readpage, mirror_num,
3069                                          *bio_flags,
3070                                          this_bio_flag,
3071                                          force_bio_submit);
3072                 if (!ret) {
3073                         nr++;
3074                         *bio_flags = this_bio_flag;
3075                 } else {
3076                         SetPageError(page);
3077                         unlock_extent(tree, cur, cur + iosize - 1);
3078                         goto out;
3079                 }
3080                 cur = cur + iosize;
3081                 pg_offset += iosize;
3082         }
3083 out:
3084         if (!nr) {
3085                 if (!PageError(page))
3086                         SetPageUptodate(page);
3087                 unlock_page(page);
3088         }
3089         return ret;
3090 }
3091
3092 static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
3093                                              struct page *pages[], int nr_pages,
3094                                              u64 start, u64 end,
3095                                              get_extent_t *get_extent,
3096                                              struct extent_map **em_cached,
3097                                              struct bio **bio, int mirror_num,
3098                                              unsigned long *bio_flags,
3099                                              u64 *prev_em_start)
3100 {
3101         struct inode *inode;
3102         struct btrfs_ordered_extent *ordered;
3103         int index;
3104
3105         inode = pages[0]->mapping->host;
3106         while (1) {
3107                 lock_extent(tree, start, end);
3108                 ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), start,
3109                                                      end - start + 1);
3110                 if (!ordered)
3111                         break;
3112                 unlock_extent(tree, start, end);
3113                 btrfs_start_ordered_extent(inode, ordered, 1);
3114                 btrfs_put_ordered_extent(ordered);
3115         }
3116
3117         for (index = 0; index < nr_pages; index++) {
3118                 __do_readpage(tree, pages[index], get_extent, em_cached, bio,
3119                               mirror_num, bio_flags, 0, prev_em_start);
3120                 put_page(pages[index]);
3121         }
3122 }
3123
3124 static void __extent_readpages(struct extent_io_tree *tree,
3125                                struct page *pages[],
3126                                int nr_pages, get_extent_t *get_extent,
3127                                struct extent_map **em_cached,
3128                                struct bio **bio, int mirror_num,
3129                                unsigned long *bio_flags,
3130                                u64 *prev_em_start)
3131 {
3132         u64 start = 0;
3133         u64 end = 0;
3134         u64 page_start;
3135         int index;
3136         int first_index = 0;
3137
3138         for (index = 0; index < nr_pages; index++) {
3139                 page_start = page_offset(pages[index]);
3140                 if (!end) {
3141                         start = page_start;
3142                         end = start + PAGE_SIZE - 1;
3143                         first_index = index;
3144                 } else if (end + 1 == page_start) {
3145                         end += PAGE_SIZE;
3146                 } else {
3147                         __do_contiguous_readpages(tree, &pages[first_index],
3148                                                   index - first_index, start,
3149                                                   end, get_extent, em_cached,
3150                                                   bio, mirror_num, bio_flags,
3151                                                   prev_em_start);
3152                         start = page_start;
3153                         end = start + PAGE_SIZE - 1;
3154                         first_index = index;
3155                 }
3156         }
3157
3158         if (end)
3159                 __do_contiguous_readpages(tree, &pages[first_index],
3160                                           index - first_index, start,
3161                                           end, get_extent, em_cached, bio,
3162                                           mirror_num, bio_flags,
3163                                           prev_em_start);
3164 }
3165
3166 static int __extent_read_full_page(struct extent_io_tree *tree,
3167                                    struct page *page,
3168                                    get_extent_t *get_extent,
3169                                    struct bio **bio, int mirror_num,
3170                                    unsigned long *bio_flags,
3171                                    unsigned int read_flags)
3172 {
3173         struct inode *inode = page->mapping->host;
3174         struct btrfs_ordered_extent *ordered;
3175         u64 start = page_offset(page);
3176         u64 end = start + PAGE_SIZE - 1;
3177         int ret;
3178
3179         while (1) {
3180                 lock_extent(tree, start, end);
3181                 ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), start,
3182                                                 PAGE_SIZE);
3183                 if (!ordered)
3184                         break;
3185                 unlock_extent(tree, start, end);
3186                 btrfs_start_ordered_extent(inode, ordered, 1);
3187                 btrfs_put_ordered_extent(ordered);
3188         }
3189
3190         ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
3191                             bio_flags, read_flags, NULL);
3192         return ret;
3193 }
3194
3195 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
3196                             get_extent_t *get_extent, int mirror_num)
3197 {
3198         struct bio *bio = NULL;
3199         unsigned long bio_flags = 0;
3200         int ret;
3201
3202         ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
3203                                       &bio_flags, 0);
3204         if (bio)
3205                 ret = submit_one_bio(bio, mirror_num, bio_flags);
3206         return ret;
3207 }
3208
3209 static void update_nr_written(struct writeback_control *wbc,
3210                               unsigned long nr_written)
3211 {
3212         wbc->nr_to_write -= nr_written;
3213 }
3214
3215 /*
3216  * helper for __extent_writepage, doing all of the delayed allocation setup.
3217  *
3218  * This returns 1 if our fill_delalloc function did all the work required
3219  * to write the page (copy into inline extent).  In this case the IO has
3220  * been started and the page is already unlocked.
3221  *
3222  * This returns 0 if all went well (page still locked)
3223  * This returns < 0 if there were errors (page still locked)
3224  */
3225 static noinline_for_stack int writepage_delalloc(struct inode *inode,
3226                               struct page *page, struct writeback_control *wbc,
3227                               struct extent_page_data *epd,
3228                               u64 delalloc_start,
3229                               unsigned long *nr_written)
3230 {
3231         struct extent_io_tree *tree = epd->tree;
3232         u64 page_end = delalloc_start + PAGE_SIZE - 1;
3233         u64 nr_delalloc;
3234         u64 delalloc_to_write = 0;
3235         u64 delalloc_end = 0;
3236         int ret;
3237         int page_started = 0;
3238
3239         if (epd->extent_locked || !tree->ops || !tree->ops->fill_delalloc)
3240                 return 0;
3241
3242         while (delalloc_end < page_end) {
3243                 nr_delalloc = find_lock_delalloc_range(inode, tree,
3244                                                page,
3245                                                &delalloc_start,
3246                                                &delalloc_end,
3247                                                BTRFS_MAX_EXTENT_SIZE);
3248                 if (nr_delalloc == 0) {
3249                         delalloc_start = delalloc_end + 1;
3250                         continue;
3251                 }
3252                 ret = tree->ops->fill_delalloc(inode, page,
3253                                                delalloc_start,
3254                                                delalloc_end,
3255                                                &page_started,
3256                                                nr_written);
3257                 /* File system has been set read-only */
3258                 if (ret) {
3259                         SetPageError(page);
3260                         /* fill_delalloc should be return < 0 for error
3261                          * but just in case, we use > 0 here meaning the
3262                          * IO is started, so we don't want to return > 0
3263                          * unless things are going well.
3264                          */
3265                         ret = ret < 0 ? ret : -EIO;
3266                         goto done;
3267                 }
3268                 /*
3269                  * delalloc_end is already one less than the total length, so
3270                  * we don't subtract one from PAGE_SIZE
3271                  */
3272                 delalloc_to_write += (delalloc_end - delalloc_start +
3273                                       PAGE_SIZE) >> PAGE_SHIFT;
3274                 delalloc_start = delalloc_end + 1;
3275         }
3276         if (wbc->nr_to_write < delalloc_to_write) {
3277                 int thresh = 8192;
3278
3279                 if (delalloc_to_write < thresh * 2)
3280                         thresh = delalloc_to_write;
3281                 wbc->nr_to_write = min_t(u64, delalloc_to_write,
3282                                          thresh);
3283         }
3284
3285         /* did the fill delalloc function already unlock and start
3286          * the IO?
3287          */
3288         if (page_started) {
3289                 /*
3290                  * we've unlocked the page, so we can't update
3291                  * the mapping's writeback index, just update
3292                  * nr_to_write.
3293                  */
3294                 wbc->nr_to_write -= *nr_written;
3295                 return 1;
3296         }
3297
3298         ret = 0;
3299
3300 done:
3301         return ret;
3302 }
3303
3304 /*
3305  * helper for __extent_writepage.  This calls the writepage start hooks,
3306  * and does the loop to map the page into extents and bios.
3307  *
3308  * We return 1 if the IO is started and the page is unlocked,
3309  * 0 if all went well (page still locked)
3310  * < 0 if there were errors (page still locked)
3311  */
3312 static noinline_for_stack int __extent_writepage_io(struct inode *inode,
3313                                  struct page *page,
3314                                  struct writeback_control *wbc,
3315                                  struct extent_page_data *epd,
3316                                  loff_t i_size,
3317                                  unsigned long nr_written,
3318                                  unsigned int write_flags, int *nr_ret)
3319 {
3320         struct extent_io_tree *tree = epd->tree;
3321         u64 start = page_offset(page);
3322         u64 page_end = start + PAGE_SIZE - 1;
3323         u64 end;
3324         u64 cur = start;
3325         u64 extent_offset;
3326         u64 block_start;
3327         u64 iosize;
3328         sector_t sector;
3329         struct extent_map *em;
3330         struct block_device *bdev;
3331         size_t pg_offset = 0;
3332         size_t blocksize;
3333         int ret = 0;
3334         int nr = 0;
3335         bool compressed;
3336
3337         if (tree->ops && tree->ops->writepage_start_hook) {
3338                 ret = tree->ops->writepage_start_hook(page, start,
3339                                                       page_end);
3340                 if (ret) {
3341                         /* Fixup worker will requeue */
3342                         if (ret == -EBUSY)
3343                                 wbc->pages_skipped++;
3344                         else
3345                                 redirty_page_for_writepage(wbc, page);
3346
3347                         update_nr_written(wbc, nr_written);
3348                         unlock_page(page);
3349                         return 1;
3350                 }
3351         }
3352
3353         /*
3354          * we don't want to touch the inode after unlocking the page,
3355          * so we update the mapping writeback index now
3356          */
3357         update_nr_written(wbc, nr_written + 1);
3358
3359         end = page_end;
3360         if (i_size <= start) {
3361                 if (tree->ops && tree->ops->writepage_end_io_hook)
3362                         tree->ops->writepage_end_io_hook(page, start,
3363                                                          page_end, NULL, 1);
3364                 goto done;
3365         }
3366
3367         blocksize = inode->i_sb->s_blocksize;
3368
3369         while (cur <= end) {
3370                 u64 em_end;
3371
3372                 if (cur >= i_size) {
3373                         if (tree->ops && tree->ops->writepage_end_io_hook)
3374                                 tree->ops->writepage_end_io_hook(page, cur,
3375                                                          page_end, NULL, 1);
3376                         break;
3377                 }
3378                 em = epd->get_extent(BTRFS_I(inode), page, pg_offset, cur,
3379                                      end - cur + 1, 1);
3380                 if (IS_ERR_OR_NULL(em)) {
3381                         SetPageError(page);
3382                         ret = PTR_ERR_OR_ZERO(em);
3383                         break;
3384                 }
3385
3386                 extent_offset = cur - em->start;
3387                 em_end = extent_map_end(em);
3388                 BUG_ON(em_end <= cur);
3389                 BUG_ON(end < cur);
3390                 iosize = min(em_end - cur, end - cur + 1);
3391                 iosize = ALIGN(iosize, blocksize);
3392                 sector = (em->block_start + extent_offset) >> 9;
3393                 bdev = em->bdev;
3394                 block_start = em->block_start;
3395                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
3396                 free_extent_map(em);
3397                 em = NULL;
3398
3399                 /*
3400                  * compressed and inline extents are written through other
3401                  * paths in the FS
3402                  */
3403                 if (compressed || block_start == EXTENT_MAP_HOLE ||
3404                     block_start == EXTENT_MAP_INLINE) {
3405                         /*
3406                          * end_io notification does not happen here for
3407                          * compressed extents
3408                          */
3409                         if (!compressed && tree->ops &&
3410                             tree->ops->writepage_end_io_hook)
3411                                 tree->ops->writepage_end_io_hook(page, cur,
3412                                                          cur + iosize - 1,
3413                                                          NULL, 1);
3414                         else if (compressed) {
3415                                 /* we don't want to end_page_writeback on
3416                                  * a compressed extent.  this happens
3417                                  * elsewhere
3418                                  */
3419                                 nr++;
3420                         }
3421
3422                         cur += iosize;
3423                         pg_offset += iosize;
3424                         continue;
3425                 }
3426
3427                 set_range_writeback(tree, cur, cur + iosize - 1);
3428                 if (!PageWriteback(page)) {
3429                         btrfs_err(BTRFS_I(inode)->root->fs_info,
3430                                    "page %lu not writeback, cur %llu end %llu",
3431                                page->index, cur, end);
3432                 }
3433
3434                 ret = submit_extent_page(REQ_OP_WRITE | write_flags, tree, wbc,
3435                                          page, sector, iosize, pg_offset,
3436                                          bdev, &epd->bio,
3437                                          end_bio_extent_writepage,
3438                                          0, 0, 0, false);
3439                 if (ret) {
3440                         SetPageError(page);
3441                         if (PageWriteback(page))
3442                                 end_page_writeback(page);
3443                 }
3444
3445                 cur = cur + iosize;
3446                 pg_offset += iosize;
3447                 nr++;
3448         }
3449 done:
3450         *nr_ret = nr;
3451         return ret;
3452 }
3453
3454 /*
3455  * the writepage semantics are similar to regular writepage.  extent
3456  * records are inserted to lock ranges in the tree, and as dirty areas
3457  * are found, they are marked writeback.  Then the lock bits are removed
3458  * and the end_io handler clears the writeback ranges
3459  */
3460 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
3461                               void *data)
3462 {
3463         struct inode *inode = page->mapping->host;
3464         struct extent_page_data *epd = data;
3465         u64 start = page_offset(page);
3466         u64 page_end = start + PAGE_SIZE - 1;
3467         int ret;
3468         int nr = 0;
3469         size_t pg_offset = 0;
3470         loff_t i_size = i_size_read(inode);
3471         unsigned long end_index = i_size >> PAGE_SHIFT;
3472         unsigned int write_flags = 0;
3473         unsigned long nr_written = 0;
3474
3475         write_flags = wbc_to_write_flags(wbc);
3476
3477         trace___extent_writepage(page, inode, wbc);
3478
3479         WARN_ON(!PageLocked(page));
3480
3481         ClearPageError(page);
3482
3483         pg_offset = i_size & (PAGE_SIZE - 1);
3484         if (page->index > end_index ||
3485            (page->index == end_index && !pg_offset)) {
3486                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
3487                 unlock_page(page);
3488                 return 0;
3489         }
3490
3491         if (page->index == end_index) {
3492                 char *userpage;
3493
3494                 userpage = kmap_atomic(page);
3495                 memset(userpage + pg_offset, 0,
3496                        PAGE_SIZE - pg_offset);
3497                 kunmap_atomic(userpage);
3498                 flush_dcache_page(page);
3499         }
3500
3501         pg_offset = 0;
3502
3503         set_page_extent_mapped(page);
3504
3505         ret = writepage_delalloc(inode, page, wbc, epd, start, &nr_written);
3506         if (ret == 1)
3507                 goto done_unlocked;
3508         if (ret)
3509                 goto done;
3510
3511         ret = __extent_writepage_io(inode, page, wbc, epd,
3512                                     i_size, nr_written, write_flags, &nr);
3513         if (ret == 1)
3514                 goto done_unlocked;
3515
3516 done:
3517         if (nr == 0) {
3518                 /* make sure the mapping tag for page dirty gets cleared */
3519                 set_page_writeback(page);
3520                 end_page_writeback(page);
3521         }
3522         if (PageError(page)) {
3523                 ret = ret < 0 ? ret : -EIO;
3524                 end_extent_writepage(page, ret, start, page_end);
3525         }
3526         unlock_page(page);
3527         return ret;
3528
3529 done_unlocked:
3530         return 0;
3531 }
3532
3533 void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
3534 {
3535         wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
3536                        TASK_UNINTERRUPTIBLE);
3537 }
3538
3539 static noinline_for_stack int
3540 lock_extent_buffer_for_io(struct extent_buffer *eb,
3541                           struct btrfs_fs_info *fs_info,
3542                           struct extent_page_data *epd)
3543 {
3544         unsigned long i, num_pages;
3545         int flush = 0;
3546         int ret = 0;
3547
3548         if (!btrfs_try_tree_write_lock(eb)) {
3549                 flush = 1;
3550                 flush_write_bio(epd);
3551                 btrfs_tree_lock(eb);
3552         }
3553
3554         if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
3555                 btrfs_tree_unlock(eb);
3556                 if (!epd->sync_io)
3557                         return 0;
3558                 if (!flush) {
3559                         flush_write_bio(epd);
3560                         flush = 1;
3561                 }
3562                 while (1) {
3563                         wait_on_extent_buffer_writeback(eb);
3564                         btrfs_tree_lock(eb);
3565                         if (!test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags))
3566                                 break;
3567                         btrfs_tree_unlock(eb);
3568                 }
3569         }
3570
3571         /*
3572          * We need to do this to prevent races in people who check if the eb is
3573          * under IO since we can end up having no IO bits set for a short period
3574          * of time.
3575          */
3576         spin_lock(&eb->refs_lock);
3577         if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3578                 set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3579                 spin_unlock(&eb->refs_lock);
3580                 btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
3581                 percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
3582                                          -eb->len,
3583                                          fs_info->dirty_metadata_batch);
3584                 ret = 1;
3585         } else {
3586                 spin_unlock(&eb->refs_lock);
3587         }
3588
3589         btrfs_tree_unlock(eb);
3590
3591         if (!ret)
3592                 return ret;
3593
3594         num_pages = num_extent_pages(eb->start, eb->len);
3595         for (i = 0; i < num_pages; i++) {
3596                 struct page *p = eb->pages[i];
3597
3598                 if (!trylock_page(p)) {
3599                         if (!flush) {
3600                                 flush_write_bio(epd);
3601                                 flush = 1;
3602                         }
3603                         lock_page(p);
3604                 }
3605         }
3606
3607         return ret;
3608 }
3609
3610 static void end_extent_buffer_writeback(struct extent_buffer *eb)
3611 {
3612         clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3613         smp_mb__after_atomic();
3614         wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
3615 }
3616
3617 static void set_btree_ioerr(struct page *page)
3618 {
3619         struct extent_buffer *eb = (struct extent_buffer *)page->private;
3620
3621         SetPageError(page);
3622         if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
3623                 return;
3624
3625         /*
3626          * If writeback for a btree extent that doesn't belong to a log tree
3627          * failed, increment the counter transaction->eb_write_errors.
3628          * We do this because while the transaction is running and before it's
3629          * committing (when we call filemap_fdata[write|wait]_range against
3630          * the btree inode), we might have
3631          * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
3632          * returns an error or an error happens during writeback, when we're
3633          * committing the transaction we wouldn't know about it, since the pages
3634          * can be no longer dirty nor marked anymore for writeback (if a
3635          * subsequent modification to the extent buffer didn't happen before the
3636          * transaction commit), which makes filemap_fdata[write|wait]_range not
3637          * able to find the pages tagged with SetPageError at transaction
3638          * commit time. So if this happens we must abort the transaction,
3639          * otherwise we commit a super block with btree roots that point to
3640          * btree nodes/leafs whose content on disk is invalid - either garbage
3641          * or the content of some node/leaf from a past generation that got
3642          * cowed or deleted and is no longer valid.
3643          *
3644          * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
3645          * not be enough - we need to distinguish between log tree extents vs
3646          * non-log tree extents, and the next filemap_fdatawait_range() call
3647          * will catch and clear such errors in the mapping - and that call might
3648          * be from a log sync and not from a transaction commit. Also, checking
3649          * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
3650          * not done and would not be reliable - the eb might have been released
3651          * from memory and reading it back again means that flag would not be
3652          * set (since it's a runtime flag, not persisted on disk).
3653          *
3654          * Using the flags below in the btree inode also makes us achieve the
3655          * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
3656          * writeback for all dirty pages and before filemap_fdatawait_range()
3657          * is called, the writeback for all dirty pages had already finished
3658          * with errors - because we were not using AS_EIO/AS_ENOSPC,
3659          * filemap_fdatawait_range() would return success, as it could not know
3660          * that writeback errors happened (the pages were no longer tagged for
3661          * writeback).
3662          */
3663         switch (eb->log_index) {
3664         case -1:
3665                 set_bit(BTRFS_FS_BTREE_ERR, &eb->fs_info->flags);
3666                 break;
3667         case 0:
3668                 set_bit(BTRFS_FS_LOG1_ERR, &eb->fs_info->flags);
3669                 break;
3670         case 1:
3671                 set_bit(BTRFS_FS_LOG2_ERR, &eb->fs_info->flags);
3672                 break;
3673         default:
3674                 BUG(); /* unexpected, logic error */
3675         }
3676 }
3677
3678 static void end_bio_extent_buffer_writepage(struct bio *bio)
3679 {
3680         struct bio_vec *bvec;
3681         struct extent_buffer *eb;
3682         int i, done;
3683
3684         ASSERT(!bio_flagged(bio, BIO_CLONED));
3685         bio_for_each_segment_all(bvec, bio, i) {
3686                 struct page *page = bvec->bv_page;
3687
3688                 eb = (struct extent_buffer *)page->private;
3689                 BUG_ON(!eb);
3690                 done = atomic_dec_and_test(&eb->io_pages);
3691
3692                 if (bio->bi_status ||
3693                     test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
3694                         ClearPageUptodate(page);
3695                         set_btree_ioerr(page);
3696                 }
3697
3698                 end_page_writeback(page);
3699
3700                 if (!done)
3701                         continue;
3702
3703                 end_extent_buffer_writeback(eb);
3704         }
3705
3706         bio_put(bio);
3707 }
3708
3709 static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
3710                         struct btrfs_fs_info *fs_info,
3711                         struct writeback_control *wbc,
3712                         struct extent_page_data *epd)
3713 {
3714         struct block_device *bdev = fs_info->fs_devices->latest_bdev;
3715         struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
3716         u64 offset = eb->start;
3717         u32 nritems;
3718         unsigned long i, num_pages;
3719         unsigned long bio_flags = 0;
3720         unsigned long start, end;
3721         unsigned int write_flags = wbc_to_write_flags(wbc) | REQ_META;
3722         int ret = 0;
3723
3724         clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
3725         num_pages = num_extent_pages(eb->start, eb->len);
3726         atomic_set(&eb->io_pages, num_pages);
3727         if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
3728                 bio_flags = EXTENT_BIO_TREE_LOG;
3729
3730         /* set btree blocks beyond nritems with 0 to avoid stale content. */
3731         nritems = btrfs_header_nritems(eb);
3732         if (btrfs_header_level(eb) > 0) {
3733                 end = btrfs_node_key_ptr_offset(nritems);
3734
3735                 memzero_extent_buffer(eb, end, eb->len - end);
3736         } else {
3737                 /*
3738                  * leaf:
3739                  * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0
3740                  */
3741                 start = btrfs_item_nr_offset(nritems);
3742                 end = BTRFS_LEAF_DATA_OFFSET + leaf_data_end(fs_info, eb);
3743                 memzero_extent_buffer(eb, start, end - start);
3744         }
3745
3746         for (i = 0; i < num_pages; i++) {
3747                 struct page *p = eb->pages[i];
3748
3749                 clear_page_dirty_for_io(p);
3750                 set_page_writeback(p);
3751                 ret = submit_extent_page(REQ_OP_WRITE | write_flags, tree, wbc,
3752                                          p, offset >> 9, PAGE_SIZE, 0, bdev,
3753                                          &epd->bio,
3754                                          end_bio_extent_buffer_writepage,
3755                                          0, epd->bio_flags, bio_flags, false);
3756                 epd->bio_flags = bio_flags;
3757                 if (ret) {
3758                         set_btree_ioerr(p);
3759                         if (PageWriteback(p))
3760                                 end_page_writeback(p);
3761                         if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
3762                                 end_extent_buffer_writeback(eb);
3763                         ret = -EIO;
3764                         break;
3765                 }
3766                 offset += PAGE_SIZE;
3767                 update_nr_written(wbc, 1);
3768                 unlock_page(p);
3769         }
3770
3771         if (unlikely(ret)) {
3772                 for (; i < num_pages; i++) {
3773                         struct page *p = eb->pages[i];
3774                         clear_page_dirty_for_io(p);
3775                         unlock_page(p);
3776                 }
3777         }
3778
3779         return ret;
3780 }
3781
3782 int btree_write_cache_pages(struct address_space *mapping,
3783                                    struct writeback_control *wbc)
3784 {
3785         struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
3786         struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
3787         struct extent_buffer *eb, *prev_eb = NULL;
3788         struct extent_page_data epd = {
3789                 .bio = NULL,
3790                 .tree = tree,
3791                 .extent_locked = 0,
3792                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
3793                 .bio_flags = 0,
3794         };
3795         int ret = 0;
3796         int done = 0;
3797         int nr_to_write_done = 0;
3798         struct pagevec pvec;
3799         int nr_pages;
3800         pgoff_t index;
3801         pgoff_t end;            /* Inclusive */
3802         int scanned = 0;
3803         int tag;
3804
3805         pagevec_init(&pvec, 0);
3806         if (wbc->range_cyclic) {
3807                 index = mapping->writeback_index; /* Start from prev offset */
3808                 end = -1;
3809         } else {
3810                 index = wbc->range_start >> PAGE_SHIFT;
3811                 end = wbc->range_end >> PAGE_SHIFT;
3812                 scanned = 1;
3813         }
3814         if (wbc->sync_mode == WB_SYNC_ALL)
3815                 tag = PAGECACHE_TAG_TOWRITE;
3816         else
3817                 tag = PAGECACHE_TAG_DIRTY;
3818 retry:
3819         if (wbc->sync_mode == WB_SYNC_ALL)
3820                 tag_pages_for_writeback(mapping, index, end);
3821         while (!done && !nr_to_write_done && (index <= end) &&
3822                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3823                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3824                 unsigned i;
3825
3826                 scanned = 1;
3827                 for (i = 0; i < nr_pages; i++) {
3828                         struct page *page = pvec.pages[i];
3829
3830                         if (!PagePrivate(page))
3831                                 continue;
3832
3833                         if (!wbc->range_cyclic && page->index > end) {
3834                                 done = 1;
3835                                 break;
3836                         }
3837
3838                         spin_lock(&mapping->private_lock);
3839                         if (!PagePrivate(page)) {
3840                                 spin_unlock(&mapping->private_lock);
3841                                 continue;
3842                         }
3843
3844                         eb = (struct extent_buffer *)page->private;
3845
3846                         /*
3847                          * Shouldn't happen and normally this would be a BUG_ON
3848                          * but no sense in crashing the users box for something
3849                          * we can survive anyway.
3850                          */
3851                         if (WARN_ON(!eb)) {
3852                                 spin_unlock(&mapping->private_lock);
3853                                 continue;
3854                         }
3855
3856                         if (eb == prev_eb) {
3857                                 spin_unlock(&mapping->private_lock);
3858                                 continue;
3859                         }
3860
3861                         ret = atomic_inc_not_zero(&eb->refs);
3862                         spin_unlock(&mapping->private_lock);
3863                         if (!ret)
3864                                 continue;
3865
3866                         prev_eb = eb;
3867                         ret = lock_extent_buffer_for_io(eb, fs_info, &epd);
3868                         if (!ret) {
3869                                 free_extent_buffer(eb);
3870                                 continue;
3871                         }
3872
3873                         ret = write_one_eb(eb, fs_info, wbc, &epd);
3874                         if (ret) {
3875                                 done = 1;
3876                                 free_extent_buffer(eb);
3877                                 break;
3878                         }
3879                         free_extent_buffer(eb);
3880
3881                         /*
3882                          * the filesystem may choose to bump up nr_to_write.
3883                          * We have to make sure to honor the new nr_to_write
3884                          * at any time
3885                          */
3886                         nr_to_write_done = wbc->nr_to_write <= 0;
3887                 }
3888                 pagevec_release(&pvec);
3889                 cond_resched();
3890         }
3891         if (!scanned && !done) {
3892                 /*
3893                  * We hit the last page and there is more work to be done: wrap
3894                  * back to the start of the file
3895                  */
3896                 scanned = 1;
3897                 index = 0;
3898                 goto retry;
3899         }
3900         flush_write_bio(&epd);
3901         return ret;
3902 }
3903
3904 /**
3905  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
3906  * @mapping: address space structure to write
3907  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
3908  * @writepage: function called for each page
3909  * @data: data passed to writepage function
3910  *
3911  * If a page is already under I/O, write_cache_pages() skips it, even
3912  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
3913  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
3914  * and msync() need to guarantee that all the data which was dirty at the time
3915  * the call was made get new I/O started against them.  If wbc->sync_mode is
3916  * WB_SYNC_ALL then we were called for data integrity and we must wait for
3917  * existing IO to complete.
3918  */
3919 static int extent_write_cache_pages(struct address_space *mapping,
3920                              struct writeback_control *wbc,
3921                              writepage_t writepage, void *data,
3922                              void (*flush_fn)(void *))
3923 {
3924         struct inode *inode = mapping->host;
3925         int ret = 0;
3926         int done = 0;
3927         int nr_to_write_done = 0;
3928         struct pagevec pvec;
3929         int nr_pages;
3930         pgoff_t index;
3931         pgoff_t end;            /* Inclusive */
3932         pgoff_t done_index;
3933         int range_whole = 0;
3934         int scanned = 0;
3935         int tag;
3936
3937         /*
3938          * We have to hold onto the inode so that ordered extents can do their
3939          * work when the IO finishes.  The alternative to this is failing to add
3940          * an ordered extent if the igrab() fails there and that is a huge pain
3941          * to deal with, so instead just hold onto the inode throughout the
3942          * writepages operation.  If it fails here we are freeing up the inode
3943          * anyway and we'd rather not waste our time writing out stuff that is
3944          * going to be truncated anyway.
3945          */
3946         if (!igrab(inode))
3947                 return 0;
3948
3949         pagevec_init(&pvec, 0);
3950         if (wbc->range_cyclic) {
3951                 index = mapping->writeback_index; /* Start from prev offset */
3952                 end = -1;
3953         } else {
3954                 index = wbc->range_start >> PAGE_SHIFT;
3955                 end = wbc->range_end >> PAGE_SHIFT;
3956                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
3957                         range_whole = 1;
3958                 scanned = 1;
3959         }
3960         if (wbc->sync_mode == WB_SYNC_ALL)
3961                 tag = PAGECACHE_TAG_TOWRITE;
3962         else
3963                 tag = PAGECACHE_TAG_DIRTY;
3964 retry:
3965         if (wbc->sync_mode == WB_SYNC_ALL)
3966                 tag_pages_for_writeback(mapping, index, end);
3967         done_index = index;
3968         while (!done && !nr_to_write_done && (index <= end) &&
3969                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3970                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3971                 unsigned i;
3972
3973                 scanned = 1;
3974                 for (i = 0; i < nr_pages; i++) {
3975                         struct page *page = pvec.pages[i];
3976
3977                         done_index = page->index;
3978                         /*
3979                          * At this point we hold neither mapping->tree_lock nor
3980                          * lock on the page itself: the page may be truncated or
3981                          * invalidated (changing page->mapping to NULL), or even
3982                          * swizzled back from swapper_space to tmpfs file
3983                          * mapping
3984                          */
3985                         if (!trylock_page(page)) {
3986                                 flush_fn(data);
3987                                 lock_page(page);
3988                         }
3989
3990                         if (unlikely(page->mapping != mapping)) {
3991                                 unlock_page(page);
3992                                 continue;
3993                         }
3994
3995                         if (!wbc->range_cyclic && page->index > end) {
3996                                 done = 1;
3997                                 unlock_page(page);
3998                                 continue;
3999                         }
4000
4001                         if (wbc->sync_mode != WB_SYNC_NONE) {
4002                                 if (PageWriteback(page))
4003                                         flush_fn(data);
4004                                 wait_on_page_writeback(page);
4005                         }
4006
4007                         if (PageWriteback(page) ||
4008                             !clear_page_dirty_for_io(page)) {
4009                                 unlock_page(page);
4010                                 continue;
4011                         }
4012
4013                         ret = (*writepage)(page, wbc, data);
4014
4015                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
4016                                 unlock_page(page);
4017                                 ret = 0;
4018                         }
4019                         if (ret < 0) {
4020                                 /*
4021                                  * done_index is set past this page,
4022                                  * so media errors will not choke
4023                                  * background writeout for the entire
4024                                  * file. This has consequences for
4025                                  * range_cyclic semantics (ie. it may
4026                                  * not be suitable for data integrity
4027                                  * writeout).
4028                                  */
4029                                 done_index = page->index + 1;
4030                                 done = 1;
4031                                 break;
4032                         }
4033
4034                         /*
4035                          * the filesystem may choose to bump up nr_to_write.
4036                          * We have to make sure to honor the new nr_to_write
4037                          * at any time
4038                          */
4039                         nr_to_write_done = wbc->nr_to_write <= 0;
4040                 }
4041                 pagevec_release(&pvec);
4042                 cond_resched();
4043         }
4044         if (!scanned && !done) {
4045                 /*
4046                  * We hit the last page and there is more work to be done: wrap
4047                  * back to the start of the file
4048                  */
4049                 scanned = 1;
4050                 index = 0;
4051                 goto retry;
4052         }
4053
4054         if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole))
4055                 mapping->writeback_index = done_index;
4056
4057         btrfs_add_delayed_iput(inode);
4058         return ret;
4059 }
4060
4061 static void flush_epd_write_bio(struct extent_page_data *epd)
4062 {
4063         if (epd->bio) {
4064                 int ret;
4065
4066                 ret = submit_one_bio(epd->bio, 0, epd->bio_flags);
4067                 BUG_ON(ret < 0); /* -ENOMEM */
4068                 epd->bio = NULL;
4069         }
4070 }
4071
4072 static noinline void flush_write_bio(void *data)
4073 {
4074         struct extent_page_data *epd = data;
4075         flush_epd_write_bio(epd);
4076 }
4077
4078 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
4079                           get_extent_t *get_extent,
4080                           struct writeback_control *wbc)
4081 {
4082         int ret;
4083         struct extent_page_data epd = {
4084                 .bio = NULL,
4085                 .tree = tree,
4086                 .get_extent = get_extent,
4087                 .extent_locked = 0,
4088                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4089                 .bio_flags = 0,
4090         };
4091
4092         ret = __extent_writepage(page, wbc, &epd);
4093
4094         flush_epd_write_bio(&epd);
4095         return ret;
4096 }
4097
4098 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
4099                               u64 start, u64 end, get_extent_t *get_extent,
4100                               int mode)
4101 {
4102         int ret = 0;
4103         struct address_space *mapping = inode->i_mapping;
4104         struct page *page;
4105         unsigned long nr_pages = (end - start + PAGE_SIZE) >>
4106                 PAGE_SHIFT;
4107
4108         struct extent_page_data epd = {
4109                 .bio = NULL,
4110                 .tree = tree,
4111                 .get_extent = get_extent,
4112                 .extent_locked = 1,
4113                 .sync_io = mode == WB_SYNC_ALL,
4114                 .bio_flags = 0,
4115         };
4116         struct writeback_control wbc_writepages = {
4117                 .sync_mode      = mode,
4118                 .nr_to_write    = nr_pages * 2,
4119                 .range_start    = start,
4120                 .range_end      = end + 1,
4121         };
4122
4123         while (start <= end) {
4124                 page = find_get_page(mapping, start >> PAGE_SHIFT);
4125                 if (clear_page_dirty_for_io(page))
4126                         ret = __extent_writepage(page, &wbc_writepages, &epd);
4127                 else {
4128                         if (tree->ops && tree->ops->writepage_end_io_hook)
4129                                 tree->ops->writepage_end_io_hook(page, start,
4130                                                  start + PAGE_SIZE - 1,
4131                                                  NULL, 1);
4132                         unlock_page(page);
4133                 }
4134                 put_page(page);
4135                 start += PAGE_SIZE;
4136         }
4137
4138         flush_epd_write_bio(&epd);
4139         return ret;
4140 }
4141
4142 int extent_writepages(struct extent_io_tree *tree,
4143                       struct address_space *mapping,
4144                       get_extent_t *get_extent,
4145                       struct writeback_control *wbc)
4146 {
4147         int ret = 0;
4148         struct extent_page_data epd = {
4149                 .bio = NULL,
4150                 .tree = tree,
4151                 .get_extent = get_extent,
4152                 .extent_locked = 0,
4153                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4154                 .bio_flags = 0,
4155         };
4156
4157         ret = extent_write_cache_pages(mapping, wbc, __extent_writepage, &epd,
4158                                        flush_write_bio);
4159         flush_epd_write_bio(&epd);
4160         return ret;
4161 }
4162
4163 int extent_readpages(struct extent_io_tree *tree,
4164                      struct address_space *mapping,
4165                      struct list_head *pages, unsigned nr_pages,
4166                      get_extent_t get_extent)
4167 {
4168         struct bio *bio = NULL;
4169         unsigned page_idx;
4170         unsigned long bio_flags = 0;
4171         struct page *pagepool[16];
4172         struct page *page;
4173         struct extent_map *em_cached = NULL;
4174         int nr = 0;
4175         u64 prev_em_start = (u64)-1;
4176
4177         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
4178                 page = list_entry(pages->prev, struct page, lru);
4179
4180                 prefetchw(&page->flags);
4181                 list_del(&page->lru);
4182                 if (add_to_page_cache_lru(page, mapping,
4183                                         page->index,
4184                                         readahead_gfp_mask(mapping))) {
4185                         put_page(page);
4186                         continue;
4187                 }
4188
4189                 pagepool[nr++] = page;
4190                 if (nr < ARRAY_SIZE(pagepool))
4191                         continue;
4192                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4193                                    &bio, 0, &bio_flags, &prev_em_start);
4194                 nr = 0;
4195         }
4196         if (nr)
4197                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4198                                    &bio, 0, &bio_flags, &prev_em_start);
4199
4200         if (em_cached)
4201                 free_extent_map(em_cached);
4202
4203         BUG_ON(!list_empty(pages));
4204         if (bio)
4205                 return submit_one_bio(bio, 0, bio_flags);
4206         return 0;
4207 }
4208
4209 /*
4210  * basic invalidatepage code, this waits on any locked or writeback
4211  * ranges corresponding to the page, and then deletes any extent state
4212  * records from the tree
4213  */
4214 int extent_invalidatepage(struct extent_io_tree *tree,
4215                           struct page *page, unsigned long offset)
4216 {
4217         struct extent_state *cached_state = NULL;
4218         u64 start = page_offset(page);
4219         u64 end = start + PAGE_SIZE - 1;
4220         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
4221
4222         start += ALIGN(offset, blocksize);
4223         if (start > end)
4224                 return 0;
4225
4226         lock_extent_bits(tree, start, end, &cached_state);
4227         wait_on_page_writeback(page);
4228         clear_extent_bit(tree, start, end,
4229                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
4230                          EXTENT_DO_ACCOUNTING,
4231                          1, 1, &cached_state, GFP_NOFS);
4232         return 0;
4233 }
4234
4235 /*
4236  * a helper for releasepage, this tests for areas of the page that
4237  * are locked or under IO and drops the related state bits if it is safe
4238  * to drop the page.
4239  */
4240 static int try_release_extent_state(struct extent_map_tree *map,
4241                                     struct extent_io_tree *tree,
4242                                     struct page *page, gfp_t mask)
4243 {
4244         u64 start = page_offset(page);
4245         u64 end = start + PAGE_SIZE - 1;
4246         int ret = 1;
4247
4248         if (test_range_bit(tree, start, end,
4249                            EXTENT_IOBITS, 0, NULL))
4250                 ret = 0;
4251         else {
4252                 /*
4253                  * at this point we can safely clear everything except the
4254                  * locked bit and the nodatasum bit
4255                  */
4256                 ret = clear_extent_bit(tree, start, end,
4257                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
4258                                  0, 0, NULL, mask);
4259
4260                 /* if clear_extent_bit failed for enomem reasons,
4261                  * we can't allow the release to continue.
4262                  */
4263                 if (ret < 0)
4264                         ret = 0;
4265                 else
4266                         ret = 1;
4267         }
4268         return ret;
4269 }
4270
4271 /*
4272  * a helper for releasepage.  As long as there are no locked extents
4273  * in the range corresponding to the page, both state records and extent
4274  * map records are removed
4275  */
4276 int try_release_extent_mapping(struct extent_map_tree *map,
4277                                struct extent_io_tree *tree, struct page *page,
4278                                gfp_t mask)
4279 {
4280         struct extent_map *em;
4281         u64 start = page_offset(page);
4282         u64 end = start + PAGE_SIZE - 1;
4283
4284         if (gfpflags_allow_blocking(mask) &&
4285             page->mapping->host->i_size > SZ_16M) {
4286                 u64 len;
4287                 while (start <= end) {
4288                         len = end - start + 1;
4289                         write_lock(&map->lock);
4290                         em = lookup_extent_mapping(map, start, len);
4291                         if (!em) {
4292                                 write_unlock(&map->lock);
4293                                 break;
4294                         }
4295                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
4296                             em->start != start) {
4297                                 write_unlock(&map->lock);
4298                                 free_extent_map(em);
4299                                 break;
4300                         }
4301                         if (!test_range_bit(tree, em->start,
4302                                             extent_map_end(em) - 1,
4303                                             EXTENT_LOCKED | EXTENT_WRITEBACK,
4304                                             0, NULL)) {
4305                                 remove_extent_mapping(map, em);
4306                                 /* once for the rb tree */
4307                                 free_extent_map(em);
4308                         }
4309                         start = extent_map_end(em);
4310                         write_unlock(&map->lock);
4311
4312                         /* once for us */
4313                         free_extent_map(em);
4314                 }
4315         }
4316         return try_release_extent_state(map, tree, page, mask);
4317 }
4318
4319 /*
4320  * helper function for fiemap, which doesn't want to see any holes.
4321  * This maps until we find something past 'last'
4322  */
4323 static struct extent_map *get_extent_skip_holes(struct inode *inode,
4324                                                 u64 offset,
4325                                                 u64 last,
4326                                                 get_extent_t *get_extent)
4327 {
4328         u64 sectorsize = btrfs_inode_sectorsize(inode);
4329         struct extent_map *em;
4330         u64 len;
4331
4332         if (offset >= last)
4333                 return NULL;
4334
4335         while (1) {
4336                 len = last - offset;
4337                 if (len == 0)
4338                         break;
4339                 len = ALIGN(len, sectorsize);
4340                 em = get_extent(BTRFS_I(inode), NULL, 0, offset, len, 0);
4341                 if (IS_ERR_OR_NULL(em))
4342                         return em;
4343
4344                 /* if this isn't a hole return it */
4345                 if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
4346                     em->block_start != EXTENT_MAP_HOLE) {
4347                         return em;
4348                 }
4349
4350                 /* this is a hole, advance to the next extent */
4351                 offset = extent_map_end(em);
4352                 free_extent_map(em);
4353                 if (offset >= last)
4354                         break;
4355         }
4356         return NULL;
4357 }
4358
4359 /*
4360  * To cache previous fiemap extent
4361  *
4362  * Will be used for merging fiemap extent
4363  */
4364 struct fiemap_cache {
4365         u64 offset;
4366         u64 phys;
4367         u64 len;
4368         u32 flags;
4369         bool cached;
4370 };
4371
4372 /*
4373  * Helper to submit fiemap extent.
4374  *
4375  * Will try to merge current fiemap extent specified by @offset, @phys,
4376  * @len and @flags with cached one.
4377  * And only when we fails to merge, cached one will be submitted as
4378  * fiemap extent.
4379  *
4380  * Return value is the same as fiemap_fill_next_extent().
4381  */
4382 static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
4383                                 struct fiemap_cache *cache,
4384                                 u64 offset, u64 phys, u64 len, u32 flags)
4385 {
4386         int ret = 0;
4387
4388         if (!cache->cached)
4389                 goto assign;
4390
4391         /*
4392          * Sanity check, extent_fiemap() should have ensured that new
4393          * fiemap extent won't overlap with cahced one.
4394          * Not recoverable.
4395          *
4396          * NOTE: Physical address can overlap, due to compression
4397          */
4398         if (cache->offset + cache->len > offset) {
4399                 WARN_ON(1);
4400                 return -EINVAL;
4401         }
4402
4403         /*
4404          * Only merges fiemap extents if
4405          * 1) Their logical addresses are continuous
4406          *
4407          * 2) Their physical addresses are continuous
4408          *    So truly compressed (physical size smaller than logical size)
4409          *    extents won't get merged with each other
4410          *
4411          * 3) Share same flags except FIEMAP_EXTENT_LAST
4412          *    So regular extent won't get merged with prealloc extent
4413          */
4414         if (cache->offset + cache->len  == offset &&
4415             cache->phys + cache->len == phys  &&
4416             (cache->flags & ~FIEMAP_EXTENT_LAST) ==
4417                         (flags & ~FIEMAP_EXTENT_LAST)) {
4418                 cache->len += len;
4419                 cache->flags |= flags;
4420                 goto try_submit_last;
4421         }
4422
4423         /* Not mergeable, need to submit cached one */
4424         ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
4425                                       cache->len, cache->flags);
4426         cache->cached = false;
4427         if (ret)
4428                 return ret;
4429 assign:
4430         cache->cached = true;
4431         cache->offset = offset;
4432         cache->phys = phys;
4433         cache->len = len;
4434         cache->flags = flags;
4435 try_submit_last:
4436         if (cache->flags & FIEMAP_EXTENT_LAST) {
4437                 ret = fiemap_fill_next_extent(fieinfo, cache->offset,
4438                                 cache->phys, cache->len, cache->flags);
4439                 cache->cached = false;
4440         }
4441         return ret;
4442 }
4443
4444 /*
4445  * Emit last fiemap cache
4446  *
4447  * The last fiemap cache may still be cached in the following case:
4448  * 0                  4k                    8k
4449  * |<- Fiemap range ->|
4450  * |<------------  First extent ----------->|
4451  *
4452  * In this case, the first extent range will be cached but not emitted.
4453  * So we must emit it before ending extent_fiemap().
4454  */
4455 static int emit_last_fiemap_cache(struct btrfs_fs_info *fs_info,
4456                                   struct fiemap_extent_info *fieinfo,
4457                                   struct fiemap_cache *cache)
4458 {
4459         int ret;
4460
4461         if (!cache->cached)
4462                 return 0;
4463
4464         ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
4465                                       cache->len, cache->flags);
4466         cache->cached = false;
4467         if (ret > 0)
4468                 ret = 0;
4469         return ret;
4470 }
4471
4472 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
4473                 __u64 start, __u64 len, get_extent_t *get_extent)
4474 {
4475         int ret = 0;
4476         u64 off = start;
4477         u64 max = start + len;
4478         u32 flags = 0;
4479         u32 found_type;
4480         u64 last;
4481         u64 last_for_get_extent = 0;
4482         u64 disko = 0;
4483         u64 isize = i_size_read(inode);
4484         struct btrfs_key found_key;
4485         struct extent_map *em = NULL;
4486         struct extent_state *cached_state = NULL;
4487         struct btrfs_path *path;
4488         struct btrfs_root *root = BTRFS_I(inode)->root;
4489         struct fiemap_cache cache = { 0 };
4490         int end = 0;
4491         u64 em_start = 0;
4492         u64 em_len = 0;
4493         u64 em_end = 0;
4494
4495         if (len == 0)
4496                 return -EINVAL;
4497
4498         path = btrfs_alloc_path();
4499         if (!path)
4500                 return -ENOMEM;
4501         path->leave_spinning = 1;
4502
4503         start = round_down(start, btrfs_inode_sectorsize(inode));
4504         len = round_up(max, btrfs_inode_sectorsize(inode)) - start;
4505
4506         /*
4507          * lookup the last file extent.  We're not using i_size here
4508          * because there might be preallocation past i_size
4509          */
4510         ret = btrfs_lookup_file_extent(NULL, root, path,
4511                         btrfs_ino(BTRFS_I(inode)), -1, 0);
4512         if (ret < 0) {
4513                 btrfs_free_path(path);
4514                 return ret;
4515         } else {
4516                 WARN_ON(!ret);
4517                 if (ret == 1)
4518                         ret = 0;
4519         }
4520
4521         path->slots[0]--;
4522         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
4523         found_type = found_key.type;
4524
4525         /* No extents, but there might be delalloc bits */
4526         if (found_key.objectid != btrfs_ino(BTRFS_I(inode)) ||
4527             found_type != BTRFS_EXTENT_DATA_KEY) {
4528                 /* have to trust i_size as the end */
4529                 last = (u64)-1;
4530                 last_for_get_extent = isize;
4531         } else {
4532                 /*
4533                  * remember the start of the last extent.  There are a
4534                  * bunch of different factors that go into the length of the
4535                  * extent, so its much less complex to remember where it started
4536                  */
4537                 last = found_key.offset;
4538                 last_for_get_extent = last + 1;
4539         }
4540         btrfs_release_path(path);
4541
4542         /*
4543          * we might have some extents allocated but more delalloc past those
4544          * extents.  so, we trust isize unless the start of the last extent is
4545          * beyond isize
4546          */
4547         if (last < isize) {
4548                 last = (u64)-1;
4549                 last_for_get_extent = isize;
4550         }
4551
4552         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4553                          &cached_state);
4554
4555         em = get_extent_skip_holes(inode, start, last_for_get_extent,
4556                                    get_extent);
4557         if (!em)
4558                 goto out;
4559         if (IS_ERR(em)) {
4560                 ret = PTR_ERR(em);
4561                 goto out;
4562         }
4563
4564         while (!end) {
4565                 u64 offset_in_extent = 0;
4566
4567                 /* break if the extent we found is outside the range */
4568                 if (em->start >= max || extent_map_end(em) < off)
4569                         break;
4570
4571                 /*
4572                  * get_extent may return an extent that starts before our
4573                  * requested range.  We have to make sure the ranges
4574                  * we return to fiemap always move forward and don't
4575                  * overlap, so adjust the offsets here
4576                  */
4577                 em_start = max(em->start, off);
4578
4579                 /*
4580                  * record the offset from the start of the extent
4581                  * for adjusting the disk offset below.  Only do this if the
4582                  * extent isn't compressed since our in ram offset may be past
4583                  * what we have actually allocated on disk.
4584                  */
4585                 if (!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4586                         offset_in_extent = em_start - em->start;
4587                 em_end = extent_map_end(em);
4588                 em_len = em_end - em_start;
4589                 disko = 0;
4590                 flags = 0;
4591
4592                 /*
4593                  * bump off for our next call to get_extent
4594                  */
4595                 off = extent_map_end(em);
4596                 if (off >= max)
4597                         end = 1;
4598
4599                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
4600                         end = 1;
4601                         flags |= FIEMAP_EXTENT_LAST;
4602                 } else if (em->block_start == EXTENT_MAP_INLINE) {
4603                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
4604                                   FIEMAP_EXTENT_NOT_ALIGNED);
4605                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
4606                         flags |= (FIEMAP_EXTENT_DELALLOC |
4607                                   FIEMAP_EXTENT_UNKNOWN);
4608                 } else if (fieinfo->fi_extents_max) {
4609                         u64 bytenr = em->block_start -
4610                                 (em->start - em->orig_start);
4611
4612                         disko = em->block_start + offset_in_extent;
4613
4614                         /*
4615                          * As btrfs supports shared space, this information
4616                          * can be exported to userspace tools via
4617                          * flag FIEMAP_EXTENT_SHARED.  If fi_extents_max == 0
4618                          * then we're just getting a count and we can skip the
4619                          * lookup stuff.
4620                          */
4621                         ret = btrfs_check_shared(root,
4622                                                  btrfs_ino(BTRFS_I(inode)),
4623                                                  bytenr);
4624                         if (ret < 0)
4625                                 goto out_free;
4626                         if (ret)
4627                                 flags |= FIEMAP_EXTENT_SHARED;
4628                         ret = 0;
4629                 }
4630                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4631                         flags |= FIEMAP_EXTENT_ENCODED;
4632                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
4633                         flags |= FIEMAP_EXTENT_UNWRITTEN;
4634
4635                 free_extent_map(em);
4636                 em = NULL;
4637                 if ((em_start >= last) || em_len == (u64)-1 ||
4638                    (last == (u64)-1 && isize <= em_end)) {
4639                         flags |= FIEMAP_EXTENT_LAST;
4640                         end = 1;
4641                 }
4642
4643                 /* now scan forward to see if this is really the last extent. */
4644                 em = get_extent_skip_holes(inode, off, last_for_get_extent,
4645                                            get_extent);
4646                 if (IS_ERR(em)) {
4647                         ret = PTR_ERR(em);
4648                         goto out;
4649                 }
4650                 if (!em) {
4651                         flags |= FIEMAP_EXTENT_LAST;
4652                         end = 1;
4653                 }
4654                 ret = emit_fiemap_extent(fieinfo, &cache, em_start, disko,
4655                                            em_len, flags);
4656                 if (ret) {
4657                         if (ret == 1)
4658                                 ret = 0;
4659                         goto out_free;
4660                 }
4661         }
4662 out_free:
4663         if (!ret)
4664                 ret = emit_last_fiemap_cache(root->fs_info, fieinfo, &cache);
4665         free_extent_map(em);
4666 out:
4667         btrfs_free_path(path);
4668         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4669                              &cached_state, GFP_NOFS);
4670         return ret;
4671 }
4672
4673 static void __free_extent_buffer(struct extent_buffer *eb)
4674 {
4675         btrfs_leak_debug_del(&eb->leak_list);
4676         kmem_cache_free(extent_buffer_cache, eb);
4677 }
4678
4679 int extent_buffer_under_io(struct extent_buffer *eb)
4680 {
4681         return (atomic_read(&eb->io_pages) ||
4682                 test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
4683                 test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4684 }
4685
4686 /*
4687  * Helper for releasing extent buffer page.
4688  */
4689 static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
4690 {
4691         unsigned long index;
4692         struct page *page;
4693         int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4694
4695         BUG_ON(extent_buffer_under_io(eb));
4696
4697         index = num_extent_pages(eb->start, eb->len);
4698         if (index == 0)
4699                 return;
4700
4701         do {
4702                 index--;
4703                 page = eb->pages[index];
4704                 if (!page)
4705                         continue;
4706                 if (mapped)
4707                         spin_lock(&page->mapping->private_lock);
4708                 /*
4709                  * We do this since we'll remove the pages after we've
4710                  * removed the eb from the radix tree, so we could race
4711                  * and have this page now attached to the new eb.  So
4712                  * only clear page_private if it's still connected to
4713                  * this eb.
4714                  */
4715                 if (PagePrivate(page) &&
4716                     page->private == (unsigned long)eb) {
4717                         BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4718                         BUG_ON(PageDirty(page));
4719                         BUG_ON(PageWriteback(page));
4720                         /*
4721                          * We need to make sure we haven't be attached
4722                          * to a new eb.
4723                          */
4724                         ClearPagePrivate(page);
4725                         set_page_private(page, 0);
4726                         /* One for the page private */
4727                         put_page(page);
4728                 }
4729
4730                 if (mapped)
4731                         spin_unlock(&page->mapping->private_lock);
4732
4733                 /* One for when we allocated the page */
4734                 put_page(page);
4735         } while (index != 0);
4736 }
4737
4738 /*
4739  * Helper for releasing the extent buffer.
4740  */
4741 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
4742 {
4743         btrfs_release_extent_buffer_page(eb);
4744         __free_extent_buffer(eb);
4745 }
4746
4747 static struct extent_buffer *
4748 __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
4749                       unsigned long len)
4750 {
4751         struct extent_buffer *eb = NULL;
4752
4753         eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
4754         eb->start = start;
4755         eb->len = len;
4756         eb->fs_info = fs_info;
4757         eb->bflags = 0;
4758         rwlock_init(&eb->lock);
4759         atomic_set(&eb->write_locks, 0);
4760         atomic_set(&eb->read_locks, 0);
4761         atomic_set(&eb->blocking_readers, 0);
4762         atomic_set(&eb->blocking_writers, 0);
4763         atomic_set(&eb->spinning_readers, 0);
4764         atomic_set(&eb->spinning_writers, 0);
4765         eb->lock_nested = 0;
4766         init_waitqueue_head(&eb->write_lock_wq);
4767         init_waitqueue_head(&eb->read_lock_wq);
4768
4769         btrfs_leak_debug_add(&eb->leak_list, &buffers);
4770
4771         spin_lock_init(&eb->refs_lock);
4772         atomic_set(&eb->refs, 1);
4773         atomic_set(&eb->io_pages, 0);
4774
4775         /*
4776          * Sanity checks, currently the maximum is 64k covered by 16x 4k pages
4777          */
4778         BUILD_BUG_ON(BTRFS_MAX_METADATA_BLOCKSIZE
4779                 > MAX_INLINE_EXTENT_BUFFER_SIZE);
4780         BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
4781
4782         return eb;
4783 }
4784
4785 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
4786 {
4787         unsigned long i;
4788         struct page *p;
4789         struct extent_buffer *new;
4790         unsigned long num_pages = num_extent_pages(src->start, src->len);
4791
4792         new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
4793         if (new == NULL)
4794                 return NULL;
4795
4796         for (i = 0; i < num_pages; i++) {
4797                 p = alloc_page(GFP_NOFS);
4798                 if (!p) {
4799                         btrfs_release_extent_buffer(new);
4800                         return NULL;
4801                 }
4802                 attach_extent_buffer_page(new, p);
4803                 WARN_ON(PageDirty(p));
4804                 SetPageUptodate(p);
4805                 new->pages[i] = p;
4806                 copy_page(page_address(p), page_address(src->pages[i]));
4807         }
4808
4809         set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
4810         set_bit(EXTENT_BUFFER_DUMMY, &new->bflags);
4811
4812         return new;
4813 }
4814
4815 struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4816                                                   u64 start, unsigned long len)
4817 {
4818         struct extent_buffer *eb;
4819         unsigned long num_pages;
4820         unsigned long i;
4821
4822         num_pages = num_extent_pages(start, len);
4823
4824         eb = __alloc_extent_buffer(fs_info, start, len);
4825         if (!eb)
4826                 return NULL;
4827
4828         for (i = 0; i < num_pages; i++) {
4829                 eb->pages[i] = alloc_page(GFP_NOFS);
4830                 if (!eb->pages[i])
4831                         goto err;
4832         }
4833         set_extent_buffer_uptodate(eb);
4834         btrfs_set_header_nritems(eb, 0);
4835         set_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4836
4837         return eb;
4838 err:
4839         for (; i > 0; i--)
4840                 __free_page(eb->pages[i - 1]);
4841         __free_extent_buffer(eb);
4842         return NULL;
4843 }
4844
4845 struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4846                                                 u64 start)
4847 {
4848         return __alloc_dummy_extent_buffer(fs_info, start, fs_info->nodesize);
4849 }
4850
4851 static void check_buffer_tree_ref(struct extent_buffer *eb)
4852 {
4853         int refs;
4854         /* the ref bit is tricky.  We have to make sure it is set
4855          * if we have the buffer dirty.   Otherwise the
4856          * code to free a buffer can end up dropping a dirty
4857          * page
4858          *
4859          * Once the ref bit is set, it won't go away while the
4860          * buffer is dirty or in writeback, and it also won't
4861          * go away while we have the reference count on the
4862          * eb bumped.
4863          *
4864          * We can't just set the ref bit without bumping the
4865          * ref on the eb because free_extent_buffer might
4866          * see the ref bit and try to clear it.  If this happens
4867          * free_extent_buffer might end up dropping our original
4868          * ref by mistake and freeing the page before we are able
4869          * to add one more ref.
4870          *
4871          * So bump the ref count first, then set the bit.  If someone
4872          * beat us to it, drop the ref we added.
4873          */
4874         refs = atomic_read(&eb->refs);
4875         if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4876                 return;
4877
4878         spin_lock(&eb->refs_lock);
4879         if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4880                 atomic_inc(&eb->refs);
4881         spin_unlock(&eb->refs_lock);
4882 }
4883
4884 static void mark_extent_buffer_accessed(struct extent_buffer *eb,
4885                 struct page *accessed)
4886 {
4887         unsigned long num_pages, i;
4888
4889         check_buffer_tree_ref(eb);
4890
4891         num_pages = num_extent_pages(eb->start, eb->len);
4892         for (i = 0; i < num_pages; i++) {
4893                 struct page *p = eb->pages[i];
4894
4895                 if (p != accessed)
4896                         mark_page_accessed(p);
4897         }
4898 }
4899
4900 struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
4901                                          u64 start)
4902 {
4903         struct extent_buffer *eb;
4904
4905         rcu_read_lock();
4906         eb = radix_tree_lookup(&fs_info->buffer_radix,
4907                                start >> PAGE_SHIFT);
4908         if (eb && atomic_inc_not_zero(&eb->refs)) {
4909                 rcu_read_unlock();
4910                 /*
4911                  * Lock our eb's refs_lock to avoid races with
4912                  * free_extent_buffer. When we get our eb it might be flagged
4913                  * with EXTENT_BUFFER_STALE and another task running
4914                  * free_extent_buffer might have seen that flag set,
4915                  * eb->refs == 2, that the buffer isn't under IO (dirty and
4916                  * writeback flags not set) and it's still in the tree (flag
4917                  * EXTENT_BUFFER_TREE_REF set), therefore being in the process
4918                  * of decrementing the extent buffer's reference count twice.
4919                  * So here we could race and increment the eb's reference count,
4920                  * clear its stale flag, mark it as dirty and drop our reference
4921                  * before the other task finishes executing free_extent_buffer,
4922                  * which would later result in an attempt to free an extent
4923                  * buffer that is dirty.
4924                  */
4925                 if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
4926                         spin_lock(&eb->refs_lock);
4927                         spin_unlock(&eb->refs_lock);
4928                 }
4929                 mark_extent_buffer_accessed(eb, NULL);
4930                 return eb;
4931         }
4932         rcu_read_unlock();
4933
4934         return NULL;
4935 }
4936
4937 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
4938 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
4939                                         u64 start)
4940 {
4941         struct extent_buffer *eb, *exists = NULL;
4942         int ret;
4943
4944         eb = find_extent_buffer(fs_info, start);
4945         if (eb)
4946                 return eb;
4947         eb = alloc_dummy_extent_buffer(fs_info, start);
4948         if (!eb)
4949                 return NULL;
4950         eb->fs_info = fs_info;
4951 again:
4952         ret = radix_tree_preload(GFP_NOFS);
4953         if (ret)
4954                 goto free_eb;
4955         spin_lock(&fs_info->buffer_lock);
4956         ret = radix_tree_insert(&fs_info->buffer_radix,
4957                                 start >> PAGE_SHIFT, eb);
4958         spin_unlock(&fs_info->buffer_lock);
4959         radix_tree_preload_end();
4960         if (ret == -EEXIST) {
4961                 exists = find_extent_buffer(fs_info, start);
4962                 if (exists)
4963                         goto free_eb;
4964                 else
4965                         goto again;
4966         }
4967         check_buffer_tree_ref(eb);
4968         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4969
4970         /*
4971          * We will free dummy extent buffer's if they come into
4972          * free_extent_buffer with a ref count of 2, but if we are using this we
4973          * want the buffers to stay in memory until we're done with them, so
4974          * bump the ref count again.
4975          */
4976         atomic_inc(&eb->refs);
4977         return eb;
4978 free_eb:
4979         btrfs_release_extent_buffer(eb);
4980         return exists;
4981 }
4982 #endif
4983
4984 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
4985                                           u64 start)
4986 {
4987         unsigned long len = fs_info->nodesize;
4988         unsigned long num_pages = num_extent_pages(start, len);
4989         unsigned long i;
4990         unsigned long index = start >> PAGE_SHIFT;
4991         struct extent_buffer *eb;
4992         struct extent_buffer *exists = NULL;
4993         struct page *p;
4994         struct address_space *mapping = fs_info->btree_inode->i_mapping;
4995         int uptodate = 1;
4996         int ret;
4997
4998         if (!IS_ALIGNED(start, fs_info->sectorsize)) {
4999                 btrfs_err(fs_info, "bad tree block start %llu", start);
5000                 return ERR_PTR(-EINVAL);
5001         }
5002
5003         eb = find_extent_buffer(fs_info, start);
5004         if (eb)
5005                 return eb;
5006
5007         eb = __alloc_extent_buffer(fs_info, start, len);
5008         if (!eb)
5009                 return ERR_PTR(-ENOMEM);
5010
5011         for (i = 0; i < num_pages; i++, index++) {
5012                 p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL);
5013                 if (!p) {
5014                         exists = ERR_PTR(-ENOMEM);
5015                         goto free_eb;
5016                 }
5017
5018                 spin_lock(&mapping->private_lock);
5019                 if (PagePrivate(p)) {
5020                         /*
5021                          * We could have already allocated an eb for this page
5022                          * and attached one so lets see if we can get a ref on
5023                          * the existing eb, and if we can we know it's good and
5024                          * we can just return that one, else we know we can just
5025                          * overwrite page->private.
5026                          */
5027                         exists = (struct extent_buffer *)p->private;
5028                         if (atomic_inc_not_zero(&exists->refs)) {
5029                                 spin_unlock(&mapping->private_lock);
5030                                 unlock_page(p);
5031                                 put_page(p);
5032                                 mark_extent_buffer_accessed(exists, p);
5033                                 goto free_eb;
5034                         }
5035                         exists = NULL;
5036
5037                         /*
5038                          * Do this so attach doesn't complain and we need to
5039                          * drop the ref the old guy had.
5040                          */
5041                         ClearPagePrivate(p);
5042                         WARN_ON(PageDirty(p));
5043                         put_page(p);
5044                 }
5045                 attach_extent_buffer_page(eb, p);
5046                 spin_unlock(&mapping->private_lock);
5047                 WARN_ON(PageDirty(p));
5048                 eb->pages[i] = p;
5049                 if (!PageUptodate(p))
5050                         uptodate = 0;
5051
5052                 /*
5053                  * see below about how we avoid a nasty race with release page
5054                  * and why we unlock later
5055                  */
5056         }
5057         if (uptodate)
5058                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5059 again:
5060         ret = radix_tree_preload(GFP_NOFS);
5061         if (ret) {
5062                 exists = ERR_PTR(ret);
5063                 goto free_eb;
5064         }
5065
5066         spin_lock(&fs_info->buffer_lock);
5067         ret = radix_tree_insert(&fs_info->buffer_radix,
5068                                 start >> PAGE_SHIFT, eb);
5069         spin_unlock(&fs_info->buffer_lock);
5070         radix_tree_preload_end();
5071         if (ret == -EEXIST) {
5072                 exists = find_extent_buffer(fs_info, start);
5073                 if (exists)
5074                         goto free_eb;
5075                 else
5076                         goto again;
5077         }
5078         /* add one reference for the tree */
5079         check_buffer_tree_ref(eb);
5080         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
5081
5082         /*
5083          * there is a race where release page may have
5084          * tried to find this extent buffer in the radix
5085          * but failed.  It will tell the VM it is safe to
5086          * reclaim the, and it will clear the page private bit.
5087          * We must make sure to set the page private bit properly
5088          * after the extent buffer is in the radix tree so
5089          * it doesn't get lost
5090          */
5091         SetPageChecked(eb->pages[0]);
5092         for (i = 1; i < num_pages; i++) {
5093                 p = eb->pages[i];
5094                 ClearPageChecked(p);
5095                 unlock_page(p);
5096         }
5097         unlock_page(eb->pages[0]);
5098         return eb;
5099
5100 free_eb:
5101         WARN_ON(!atomic_dec_and_test(&eb->refs));
5102         for (i = 0; i < num_pages; i++) {
5103                 if (eb->pages[i])
5104                         unlock_page(eb->pages[i]);
5105         }
5106
5107         btrfs_release_extent_buffer(eb);
5108         return exists;
5109 }
5110
5111 static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
5112 {
5113         struct extent_buffer *eb =
5114                         container_of(head, struct extent_buffer, rcu_head);
5115
5116         __free_extent_buffer(eb);
5117 }
5118
5119 /* Expects to have eb->eb_lock already held */
5120 static int release_extent_buffer(struct extent_buffer *eb)
5121 {
5122         WARN_ON(atomic_read(&eb->refs) == 0);
5123         if (atomic_dec_and_test(&eb->refs)) {
5124                 if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) {
5125                         struct btrfs_fs_info *fs_info = eb->fs_info;
5126
5127                         spin_unlock(&eb->refs_lock);
5128
5129                         spin_lock(&fs_info->buffer_lock);
5130                         radix_tree_delete(&fs_info->buffer_radix,
5131                                           eb->start >> PAGE_SHIFT);
5132                         spin_unlock(&fs_info->buffer_lock);
5133                 } else {
5134                         spin_unlock(&eb->refs_lock);
5135                 }
5136
5137                 /* Should be safe to release our pages at this point */
5138                 btrfs_release_extent_buffer_page(eb);
5139 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
5140                 if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))) {
5141                         __free_extent_buffer(eb);
5142                         return 1;
5143                 }
5144 #endif
5145                 call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
5146                 return 1;
5147         }
5148         spin_unlock(&eb->refs_lock);
5149
5150         return 0;
5151 }
5152
5153 void free_extent_buffer(struct extent_buffer *eb)
5154 {
5155         int refs;
5156         int old;
5157         if (!eb)
5158                 return;
5159
5160         while (1) {
5161                 refs = atomic_read(&eb->refs);
5162                 if (refs <= 3)
5163                         break;
5164                 old = atomic_cmpxchg(&eb->refs, refs, refs - 1);
5165                 if (old == refs)
5166                         return;
5167         }
5168
5169         spin_lock(&eb->refs_lock);
5170         if (atomic_read(&eb->refs) == 2 &&
5171             test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))
5172                 atomic_dec(&eb->refs);
5173
5174         if (atomic_read(&eb->refs) == 2 &&
5175             test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
5176             !extent_buffer_under_io(eb) &&
5177             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5178                 atomic_dec(&eb->refs);
5179
5180         /*
5181          * I know this is terrible, but it's temporary until we stop tracking
5182          * the uptodate bits and such for the extent buffers.
5183          */
5184         release_extent_buffer(eb);
5185 }
5186
5187 void free_extent_buffer_stale(struct extent_buffer *eb)
5188 {
5189         if (!eb)
5190                 return;
5191
5192         spin_lock(&eb->refs_lock);
5193         set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
5194
5195         if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
5196             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5197                 atomic_dec(&eb->refs);
5198         release_extent_buffer(eb);
5199 }
5200
5201 void clear_extent_buffer_dirty(struct extent_buffer *eb)
5202 {
5203         unsigned long i;
5204         unsigned long num_pages;
5205         struct page *page;
5206
5207         num_pages = num_extent_pages(eb->start, eb->len);
5208
5209         for (i = 0; i < num_pages; i++) {
5210                 page = eb->pages[i];
5211                 if (!PageDirty(page))
5212                         continue;
5213
5214                 lock_page(page);
5215                 WARN_ON(!PagePrivate(page));
5216
5217                 clear_page_dirty_for_io(page);
5218                 spin_lock_irq(&page->mapping->tree_lock);
5219                 if (!PageDirty(page)) {
5220                         radix_tree_tag_clear(&page->mapping->page_tree,
5221                                                 page_index(page),
5222                                                 PAGECACHE_TAG_DIRTY);
5223                 }
5224                 spin_unlock_irq(&page->mapping->tree_lock);
5225                 ClearPageError(page);
5226                 unlock_page(page);
5227         }
5228         WARN_ON(atomic_read(&eb->refs) == 0);
5229 }
5230
5231 int set_extent_buffer_dirty(struct extent_buffer *eb)
5232 {
5233         unsigned long i;
5234         unsigned long num_pages;
5235         int was_dirty = 0;
5236
5237         check_buffer_tree_ref(eb);
5238
5239         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
5240
5241         num_pages = num_extent_pages(eb->start, eb->len);
5242         WARN_ON(atomic_read(&eb->refs) == 0);
5243         WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
5244
5245         for (i = 0; i < num_pages; i++)
5246                 set_page_dirty(eb->pages[i]);
5247         return was_dirty;
5248 }
5249
5250 void clear_extent_buffer_uptodate(struct extent_buffer *eb)
5251 {
5252         unsigned long i;
5253         struct page *page;
5254         unsigned long num_pages;
5255
5256         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5257         num_pages = num_extent_pages(eb->start, eb->len);
5258         for (i = 0; i < num_pages; i++) {
5259                 page = eb->pages[i];
5260                 if (page)
5261                         ClearPageUptodate(page);
5262         }
5263 }
5264
5265 void set_extent_buffer_uptodate(struct extent_buffer *eb)
5266 {
5267         unsigned long i;
5268         struct page *page;
5269         unsigned long num_pages;
5270
5271         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5272         num_pages = num_extent_pages(eb->start, eb->len);
5273         for (i = 0; i < num_pages; i++) {
5274                 page = eb->pages[i];
5275                 SetPageUptodate(page);
5276         }
5277 }
5278
5279 int extent_buffer_uptodate(struct extent_buffer *eb)
5280 {
5281         return test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5282 }
5283
5284 int read_extent_buffer_pages(struct extent_io_tree *tree,
5285                              struct extent_buffer *eb, int wait,
5286                              get_extent_t *get_extent, int mirror_num)
5287 {
5288         unsigned long i;
5289         struct page *page;
5290         int err;
5291         int ret = 0;
5292         int locked_pages = 0;
5293         int all_uptodate = 1;
5294         unsigned long num_pages;
5295         unsigned long num_reads = 0;
5296         struct bio *bio = NULL;
5297         unsigned long bio_flags = 0;
5298
5299         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
5300                 return 0;
5301
5302         num_pages = num_extent_pages(eb->start, eb->len);
5303         for (i = 0; i < num_pages; i++) {
5304                 page = eb->pages[i];
5305                 if (wait == WAIT_NONE) {
5306                         if (!trylock_page(page))
5307                                 goto unlock_exit;
5308                 } else {
5309                         lock_page(page);
5310                 }
5311                 locked_pages++;
5312         }
5313         /*
5314          * We need to firstly lock all pages to make sure that
5315          * the uptodate bit of our pages won't be affected by
5316          * clear_extent_buffer_uptodate().
5317          */
5318         for (i = 0; i < num_pages; i++) {
5319                 page = eb->pages[i];
5320                 if (!PageUptodate(page)) {
5321                         num_reads++;
5322                         all_uptodate = 0;
5323                 }
5324         }
5325
5326         if (all_uptodate) {
5327                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5328                 goto unlock_exit;
5329         }
5330
5331         clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
5332         eb->read_mirror = 0;
5333         atomic_set(&eb->io_pages, num_reads);
5334         for (i = 0; i < num_pages; i++) {
5335                 page = eb->pages[i];
5336
5337                 if (!PageUptodate(page)) {
5338                         if (ret) {
5339                                 atomic_dec(&eb->io_pages);
5340                                 unlock_page(page);
5341                                 continue;
5342                         }
5343
5344                         ClearPageError(page);
5345                         err = __extent_read_full_page(tree, page,
5346                                                       get_extent, &bio,
5347                                                       mirror_num, &bio_flags,
5348                                                       REQ_META);
5349                         if (err) {
5350                                 ret = err;
5351                                 /*
5352                                  * We use &bio in above __extent_read_full_page,
5353                                  * so we ensure that if it returns error, the
5354                                  * current page fails to add itself to bio and
5355                                  * it's been unlocked.
5356                                  *
5357                                  * We must dec io_pages by ourselves.
5358                                  */
5359                                 atomic_dec(&eb->io_pages);
5360                         }
5361                 } else {
5362                         unlock_page(page);
5363                 }
5364         }
5365
5366         if (bio) {
5367                 err = submit_one_bio(bio, mirror_num, bio_flags);
5368                 if (err)
5369                         return err;
5370         }
5371
5372         if (ret || wait != WAIT_COMPLETE)
5373                 return ret;
5374
5375         for (i = 0; i < num_pages; i++) {
5376                 page = eb->pages[i];
5377                 wait_on_page_locked(page);
5378                 if (!PageUptodate(page))
5379                         ret = -EIO;
5380         }
5381
5382         return ret;
5383
5384 unlock_exit:
5385         while (locked_pages > 0) {
5386                 locked_pages--;
5387                 page = eb->pages[locked_pages];
5388                 unlock_page(page);
5389         }
5390         return ret;
5391 }
5392
5393 void read_extent_buffer(const struct extent_buffer *eb, void *dstv,
5394                         unsigned long start, unsigned long len)
5395 {
5396         size_t cur;
5397         size_t offset;
5398         struct page *page;
5399         char *kaddr;
5400         char *dst = (char *)dstv;
5401         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5402         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5403
5404         if (start + len > eb->len) {
5405                 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, wanted %lu %lu\n",
5406                      eb->start, eb->len, start, len);
5407                 memset(dst, 0, len);
5408                 return;
5409         }
5410
5411         offset = (start_offset + start) & (PAGE_SIZE - 1);
5412
5413         while (len > 0) {
5414                 page = eb->pages[i];
5415
5416                 cur = min(len, (PAGE_SIZE - offset));
5417                 kaddr = page_address(page);
5418                 memcpy(dst, kaddr + offset, cur);
5419
5420                 dst += cur;
5421                 len -= cur;
5422                 offset = 0;
5423                 i++;
5424         }
5425 }
5426
5427 int read_extent_buffer_to_user(const struct extent_buffer *eb,
5428                                void __user *dstv,
5429                                unsigned long start, unsigned long len)
5430 {
5431         size_t cur;
5432         size_t offset;
5433         struct page *page;
5434         char *kaddr;
5435         char __user *dst = (char __user *)dstv;
5436         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5437         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5438         int ret = 0;
5439
5440         WARN_ON(start > eb->len);
5441         WARN_ON(start + len > eb->start + eb->len);
5442
5443         offset = (start_offset + start) & (PAGE_SIZE - 1);
5444
5445         while (len > 0) {
5446                 page = eb->pages[i];
5447
5448                 cur = min(len, (PAGE_SIZE - offset));
5449                 kaddr = page_address(page);
5450                 if (copy_to_user(dst, kaddr + offset, cur)) {
5451                         ret = -EFAULT;
5452                         break;
5453                 }
5454
5455                 dst += cur;
5456                 len -= cur;
5457                 offset = 0;
5458                 i++;
5459         }
5460
5461         return ret;
5462 }
5463
5464 /*
5465  * return 0 if the item is found within a page.
5466  * return 1 if the item spans two pages.
5467  * return -EINVAL otherwise.
5468  */
5469 int map_private_extent_buffer(const struct extent_buffer *eb,
5470                               unsigned long start, unsigned long min_len,
5471                               char **map, unsigned long *map_start,
5472                               unsigned long *map_len)
5473 {
5474         size_t offset = start & (PAGE_SIZE - 1);
5475         char *kaddr;
5476         struct page *p;
5477         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5478         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5479         unsigned long end_i = (start_offset + start + min_len - 1) >>
5480                 PAGE_SHIFT;
5481
5482         if (start + min_len > eb->len) {
5483                 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, wanted %lu %lu\n",
5484                        eb->start, eb->len, start, min_len);
5485                 return -EINVAL;
5486         }
5487
5488         if (i != end_i)
5489                 return 1;
5490
5491         if (i == 0) {
5492                 offset = start_offset;
5493                 *map_start = 0;
5494         } else {
5495                 offset = 0;
5496                 *map_start = ((u64)i << PAGE_SHIFT) - start_offset;
5497         }
5498
5499         p = eb->pages[i];
5500         kaddr = page_address(p);
5501         *map = kaddr + offset;
5502         *map_len = PAGE_SIZE - offset;
5503         return 0;
5504 }
5505
5506 int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
5507                          unsigned long start, unsigned long len)
5508 {
5509         size_t cur;
5510         size_t offset;
5511         struct page *page;
5512         char *kaddr;
5513         char *ptr = (char *)ptrv;
5514         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5515         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5516         int ret = 0;
5517
5518         WARN_ON(start > eb->len);
5519         WARN_ON(start + len > eb->start + eb->len);
5520
5521         offset = (start_offset + start) & (PAGE_SIZE - 1);
5522
5523         while (len > 0) {
5524                 page = eb->pages[i];
5525
5526                 cur = min(len, (PAGE_SIZE - offset));
5527
5528                 kaddr = page_address(page);
5529                 ret = memcmp(ptr, kaddr + offset, cur);
5530                 if (ret)
5531                         break;
5532
5533                 ptr += cur;
5534                 len -= cur;
5535                 offset = 0;
5536                 i++;
5537         }
5538         return ret;
5539 }
5540
5541 void write_extent_buffer_chunk_tree_uuid(struct extent_buffer *eb,
5542                 const void *srcv)
5543 {
5544         char *kaddr;
5545
5546         WARN_ON(!PageUptodate(eb->pages[0]));
5547         kaddr = page_address(eb->pages[0]);
5548         memcpy(kaddr + offsetof(struct btrfs_header, chunk_tree_uuid), srcv,
5549                         BTRFS_FSID_SIZE);
5550 }
5551
5552 void write_extent_buffer_fsid(struct extent_buffer *eb, const void *srcv)
5553 {
5554         char *kaddr;
5555
5556         WARN_ON(!PageUptodate(eb->pages[0]));
5557         kaddr = page_address(eb->pages[0]);
5558         memcpy(kaddr + offsetof(struct btrfs_header, fsid), srcv,
5559                         BTRFS_FSID_SIZE);
5560 }
5561
5562 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
5563                          unsigned long start, unsigned long len)
5564 {
5565         size_t cur;
5566         size_t offset;
5567         struct page *page;
5568         char *kaddr;
5569         char *src = (char *)srcv;
5570         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5571         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5572
5573         WARN_ON(start > eb->len);
5574         WARN_ON(start + len > eb->start + eb->len);
5575
5576         offset = (start_offset + start) & (PAGE_SIZE - 1);
5577
5578         while (len > 0) {
5579                 page = eb->pages[i];
5580                 WARN_ON(!PageUptodate(page));
5581
5582                 cur = min(len, PAGE_SIZE - offset);
5583                 kaddr = page_address(page);
5584                 memcpy(kaddr + offset, src, cur);
5585
5586                 src += cur;
5587                 len -= cur;
5588                 offset = 0;
5589                 i++;
5590         }
5591 }
5592
5593 void memzero_extent_buffer(struct extent_buffer *eb, unsigned long start,
5594                 unsigned long len)
5595 {
5596         size_t cur;
5597         size_t offset;
5598         struct page *page;
5599         char *kaddr;
5600         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5601         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5602
5603         WARN_ON(start > eb->len);
5604         WARN_ON(start + len > eb->start + eb->len);
5605
5606         offset = (start_offset + start) & (PAGE_SIZE - 1);
5607
5608         while (len > 0) {
5609                 page = eb->pages[i];
5610                 WARN_ON(!PageUptodate(page));
5611
5612                 cur = min(len, PAGE_SIZE - offset);
5613                 kaddr = page_address(page);
5614                 memset(kaddr + offset, 0, cur);
5615
5616                 len -= cur;
5617                 offset = 0;
5618                 i++;
5619         }
5620 }
5621
5622 void copy_extent_buffer_full(struct extent_buffer *dst,
5623                              struct extent_buffer *src)
5624 {
5625         int i;
5626         unsigned num_pages;
5627
5628         ASSERT(dst->len == src->len);
5629
5630         num_pages = num_extent_pages(dst->start, dst->len);
5631         for (i = 0; i < num_pages; i++)
5632                 copy_page(page_address(dst->pages[i]),
5633                                 page_address(src->pages[i]));
5634 }
5635
5636 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
5637                         unsigned long dst_offset, unsigned long src_offset,
5638                         unsigned long len)
5639 {
5640         u64 dst_len = dst->len;
5641         size_t cur;
5642         size_t offset;
5643         struct page *page;
5644         char *kaddr;
5645         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5646         unsigned long i = (start_offset + dst_offset) >> PAGE_SHIFT;
5647
5648         WARN_ON(src->len != dst_len);
5649
5650         offset = (start_offset + dst_offset) &
5651                 (PAGE_SIZE - 1);
5652
5653         while (len > 0) {
5654                 page = dst->pages[i];
5655                 WARN_ON(!PageUptodate(page));
5656
5657                 cur = min(len, (unsigned long)(PAGE_SIZE - offset));
5658
5659                 kaddr = page_address(page);
5660                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
5661
5662                 src_offset += cur;
5663                 len -= cur;
5664                 offset = 0;
5665                 i++;
5666         }
5667 }
5668
5669 void le_bitmap_set(u8 *map, unsigned int start, int len)
5670 {
5671         u8 *p = map + BIT_BYTE(start);
5672         const unsigned int size = start + len;
5673         int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
5674         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
5675
5676         while (len - bits_to_set >= 0) {
5677                 *p |= mask_to_set;
5678                 len -= bits_to_set;
5679                 bits_to_set = BITS_PER_BYTE;
5680                 mask_to_set = ~0;
5681                 p++;
5682         }
5683         if (len) {
5684                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
5685                 *p |= mask_to_set;
5686         }
5687 }
5688
5689 void le_bitmap_clear(u8 *map, unsigned int start, int len)
5690 {
5691         u8 *p = map + BIT_BYTE(start);
5692         const unsigned int size = start + len;
5693         int bits_to_clear = BITS_PER_BYTE - (start % BITS_PER_BYTE);
5694         u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(start);
5695
5696         while (len - bits_to_clear >= 0) {
5697                 *p &= ~mask_to_clear;
5698                 len -= bits_to_clear;
5699                 bits_to_clear = BITS_PER_BYTE;
5700                 mask_to_clear = ~0;
5701                 p++;
5702         }
5703         if (len) {
5704                 mask_to_clear &= BITMAP_LAST_BYTE_MASK(size);
5705                 *p &= ~mask_to_clear;
5706         }
5707 }
5708
5709 /*
5710  * eb_bitmap_offset() - calculate the page and offset of the byte containing the
5711  * given bit number
5712  * @eb: the extent buffer
5713  * @start: offset of the bitmap item in the extent buffer
5714  * @nr: bit number
5715  * @page_index: return index of the page in the extent buffer that contains the
5716  * given bit number
5717  * @page_offset: return offset into the page given by page_index
5718  *
5719  * This helper hides the ugliness of finding the byte in an extent buffer which
5720  * contains a given bit.
5721  */
5722 static inline void eb_bitmap_offset(struct extent_buffer *eb,
5723                                     unsigned long start, unsigned long nr,
5724                                     unsigned long *page_index,
5725                                     size_t *page_offset)
5726 {
5727         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5728         size_t byte_offset = BIT_BYTE(nr);
5729         size_t offset;
5730
5731         /*
5732          * The byte we want is the offset of the extent buffer + the offset of
5733          * the bitmap item in the extent buffer + the offset of the byte in the
5734          * bitmap item.
5735          */
5736         offset = start_offset + start + byte_offset;
5737
5738         *page_index = offset >> PAGE_SHIFT;
5739         *page_offset = offset & (PAGE_SIZE - 1);
5740 }
5741
5742 /**
5743  * extent_buffer_test_bit - determine whether a bit in a bitmap item is set
5744  * @eb: the extent buffer
5745  * @start: offset of the bitmap item in the extent buffer
5746  * @nr: bit number to test
5747  */
5748 int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
5749                            unsigned long nr)
5750 {
5751         u8 *kaddr;
5752         struct page *page;
5753         unsigned long i;
5754         size_t offset;
5755
5756         eb_bitmap_offset(eb, start, nr, &i, &offset);
5757         page = eb->pages[i];
5758         WARN_ON(!PageUptodate(page));
5759         kaddr = page_address(page);
5760         return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1)));
5761 }
5762
5763 /**
5764  * extent_buffer_bitmap_set - set an area of a bitmap
5765  * @eb: the extent buffer
5766  * @start: offset of the bitmap item in the extent buffer
5767  * @pos: bit number of the first bit
5768  * @len: number of bits to set
5769  */
5770 void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
5771                               unsigned long pos, unsigned long len)
5772 {
5773         u8 *kaddr;
5774         struct page *page;
5775         unsigned long i;
5776         size_t offset;
5777         const unsigned int size = pos + len;
5778         int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5779         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(pos);
5780
5781         eb_bitmap_offset(eb, start, pos, &i, &offset);
5782         page = eb->pages[i];
5783         WARN_ON(!PageUptodate(page));
5784         kaddr = page_address(page);
5785
5786         while (len >= bits_to_set) {
5787                 kaddr[offset] |= mask_to_set;
5788                 len -= bits_to_set;
5789                 bits_to_set = BITS_PER_BYTE;
5790                 mask_to_set = ~0;
5791                 if (++offset >= PAGE_SIZE && len > 0) {
5792                         offset = 0;
5793                         page = eb->pages[++i];
5794                         WARN_ON(!PageUptodate(page));
5795                         kaddr = page_address(page);
5796                 }
5797         }
5798         if (len) {
5799                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
5800                 kaddr[offset] |= mask_to_set;
5801         }
5802 }
5803
5804
5805 /**
5806  * extent_buffer_bitmap_clear - clear an area of a bitmap
5807  * @eb: the extent buffer
5808  * @start: offset of the bitmap item in the extent buffer
5809  * @pos: bit number of the first bit
5810  * @len: number of bits to clear
5811  */
5812 void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
5813                                 unsigned long pos, unsigned long len)
5814 {
5815         u8 *kaddr;
5816         struct page *page;
5817         unsigned long i;
5818         size_t offset;
5819         const unsigned int size = pos + len;
5820         int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5821         u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos);
5822
5823         eb_bitmap_offset(eb, start, pos, &i, &offset);
5824         page = eb->pages[i];
5825         WARN_ON(!PageUptodate(page));
5826         kaddr = page_address(page);
5827
5828         while (len >= bits_to_clear) {
5829                 kaddr[offset] &= ~mask_to_clear;
5830                 len -= bits_to_clear;
5831                 bits_to_clear = BITS_PER_BYTE;
5832                 mask_to_clear = ~0;
5833                 if (++offset >= PAGE_SIZE && len > 0) {
5834                         offset = 0;
5835                         page = eb->pages[++i];
5836                         WARN_ON(!PageUptodate(page));
5837                         kaddr = page_address(page);
5838                 }
5839         }
5840         if (len) {
5841                 mask_to_clear &= BITMAP_LAST_BYTE_MASK(size);
5842                 kaddr[offset] &= ~mask_to_clear;
5843         }
5844 }
5845
5846 static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
5847 {
5848         unsigned long distance = (src > dst) ? src - dst : dst - src;
5849         return distance < len;
5850 }
5851
5852 static void copy_pages(struct page *dst_page, struct page *src_page,
5853                        unsigned long dst_off, unsigned long src_off,
5854                        unsigned long len)
5855 {
5856         char *dst_kaddr = page_address(dst_page);
5857         char *src_kaddr;
5858         int must_memmove = 0;
5859
5860         if (dst_page != src_page) {
5861                 src_kaddr = page_address(src_page);
5862         } else {
5863                 src_kaddr = dst_kaddr;
5864                 if (areas_overlap(src_off, dst_off, len))
5865                         must_memmove = 1;
5866         }
5867
5868         if (must_memmove)
5869                 memmove(dst_kaddr + dst_off, src_kaddr + src_off, len);
5870         else
5871                 memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
5872 }
5873
5874 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5875                            unsigned long src_offset, unsigned long len)
5876 {
5877         struct btrfs_fs_info *fs_info = dst->fs_info;
5878         size_t cur;
5879         size_t dst_off_in_page;
5880         size_t src_off_in_page;
5881         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5882         unsigned long dst_i;
5883         unsigned long src_i;
5884
5885         if (src_offset + len > dst->len) {
5886                 btrfs_err(fs_info,
5887                         "memmove bogus src_offset %lu move len %lu dst len %lu",
5888                          src_offset, len, dst->len);
5889                 BUG_ON(1);
5890         }
5891         if (dst_offset + len > dst->len) {
5892                 btrfs_err(fs_info,
5893                         "memmove bogus dst_offset %lu move len %lu dst len %lu",
5894                          dst_offset, len, dst->len);
5895                 BUG_ON(1);
5896         }
5897
5898         while (len > 0) {
5899                 dst_off_in_page = (start_offset + dst_offset) &
5900                         (PAGE_SIZE - 1);
5901                 src_off_in_page = (start_offset + src_offset) &
5902                         (PAGE_SIZE - 1);
5903
5904                 dst_i = (start_offset + dst_offset) >> PAGE_SHIFT;
5905                 src_i = (start_offset + src_offset) >> PAGE_SHIFT;
5906
5907                 cur = min(len, (unsigned long)(PAGE_SIZE -
5908                                                src_off_in_page));
5909                 cur = min_t(unsigned long, cur,
5910                         (unsigned long)(PAGE_SIZE - dst_off_in_page));
5911
5912                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
5913                            dst_off_in_page, src_off_in_page, cur);
5914
5915                 src_offset += cur;
5916                 dst_offset += cur;
5917                 len -= cur;
5918         }
5919 }
5920
5921 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5922                            unsigned long src_offset, unsigned long len)
5923 {
5924         struct btrfs_fs_info *fs_info = dst->fs_info;
5925         size_t cur;
5926         size_t dst_off_in_page;
5927         size_t src_off_in_page;
5928         unsigned long dst_end = dst_offset + len - 1;
5929         unsigned long src_end = src_offset + len - 1;
5930         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5931         unsigned long dst_i;
5932         unsigned long src_i;
5933
5934         if (src_offset + len > dst->len) {
5935                 btrfs_err(fs_info,
5936                           "memmove bogus src_offset %lu move len %lu len %lu",
5937                           src_offset, len, dst->len);
5938                 BUG_ON(1);
5939         }
5940         if (dst_offset + len > dst->len) {
5941                 btrfs_err(fs_info,
5942                           "memmove bogus dst_offset %lu move len %lu len %lu",
5943                           dst_offset, len, dst->len);
5944                 BUG_ON(1);
5945         }
5946         if (dst_offset < src_offset) {
5947                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
5948                 return;
5949         }
5950         while (len > 0) {
5951                 dst_i = (start_offset + dst_end) >> PAGE_SHIFT;
5952                 src_i = (start_offset + src_end) >> PAGE_SHIFT;
5953
5954                 dst_off_in_page = (start_offset + dst_end) &
5955                         (PAGE_SIZE - 1);
5956                 src_off_in_page = (start_offset + src_end) &
5957                         (PAGE_SIZE - 1);
5958
5959                 cur = min_t(unsigned long, len, src_off_in_page + 1);
5960                 cur = min(cur, dst_off_in_page + 1);
5961                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
5962                            dst_off_in_page - cur + 1,
5963                            src_off_in_page - cur + 1, cur);
5964
5965                 dst_end -= cur;
5966                 src_end -= cur;
5967                 len -= cur;
5968         }
5969 }
5970
5971 int try_release_extent_buffer(struct page *page)
5972 {
5973         struct extent_buffer *eb;
5974
5975         /*
5976          * We need to make sure nobody is attaching this page to an eb right
5977          * now.
5978          */
5979         spin_lock(&page->mapping->private_lock);
5980         if (!PagePrivate(page)) {
5981                 spin_unlock(&page->mapping->private_lock);
5982                 return 1;
5983         }
5984
5985         eb = (struct extent_buffer *)page->private;
5986         BUG_ON(!eb);
5987
5988         /*
5989          * This is a little awful but should be ok, we need to make sure that
5990          * the eb doesn't disappear out from under us while we're looking at
5991          * this page.
5992          */
5993         spin_lock(&eb->refs_lock);
5994         if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
5995                 spin_unlock(&eb->refs_lock);
5996                 spin_unlock(&page->mapping->private_lock);
5997                 return 0;
5998         }
5999         spin_unlock(&page->mapping->private_lock);
6000
6001         /*
6002          * If tree ref isn't set then we know the ref on this eb is a real ref,
6003          * so just return, this page will likely be freed soon anyway.
6004          */
6005         if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
6006                 spin_unlock(&eb->refs_lock);
6007                 return 0;
6008         }
6009
6010         return release_extent_buffer(eb);
6011 }