fs/btrfs/extent_io.c

   1 #include <linux/bitops.h>
   2 #include <linux/slab.h>
   3 #include <linux/bio.h>
   4 #include <linux/mm.h>
   5 #include <linux/pagemap.h>
   6 #include <linux/page-flags.h>
   7 #include <linux/spinlock.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/swap.h>
  10 #include <linux/writeback.h>
  11 #include <linux/pagevec.h>
  12 #include <linux/prefetch.h>
  13 #include <linux/cleancache.h>
  14 #include "extent_io.h"
  15 #include "extent_map.h"
  16 #include "ctree.h"
  17 #include "btrfs_inode.h"
  18 #include "volumes.h"
  19 #include "check-integrity.h"
  20 #include "locking.h"
  21 #include "rcu-string.h"
  22 #include "backref.h"
  23 #include "transaction.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                        atomic_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                 printk(KERN_ERR "BTRFS: buffer leak start %llu len %lu "
  79                        "refs %d\n",
  80                        eb->start, eb->len, atomic_read(&eb->refs));
  81                 list_del(&eb->leak_list);
  82                 kmem_cache_free(extent_buffer_cache, eb);
  83         }
  84 }
  85
  86 #define btrfs_debug_check_extent_io_range(tree, start, end)             \
  87         __btrfs_debug_check_extent_io_range(__func__, (tree), (start), (end))
  88 static inline void __btrfs_debug_check_extent_io_range(const char *caller,
  89                 struct extent_io_tree *tree, u64 start, u64 end)
  90 {
  91         struct inode *inode;
  92         u64 isize;
  93
  94         if (!tree->mapping)
  95                 return;
  96
  97         inode = tree->mapping->host;
  98         isize = i_size_read(inode);
  99         if (end >= PAGE_SIZE && (end % 2) == 0 && end != isize - 1) {
 100                 btrfs_debug_rl(BTRFS_I(inode)->root->fs_info,
 101                     "%s: ino %llu isize %llu odd range [%llu,%llu]",
 102                                 caller, btrfs_ino(inode), isize, start, end);
 103         }
 104 }
 105 #else
 106 #define btrfs_leak_debug_add(new, head) do {} while (0)
 107 #define btrfs_leak_debug_del(entry)     do {} while (0)
 108 #define btrfs_leak_debug_check()        do {} while (0)
 109 #define btrfs_debug_check_extent_io_range(c, s, e)      do {} while (0)
 110 #endif
 111
 112 #define BUFFER_LRU_MAX 64
 113
 114 struct tree_entry {
 115         u64 start;
 116         u64 end;
 117         struct rb_node rb_node;
 118 };
 119
 120 struct extent_page_data {
 121         struct bio *bio;
 122         struct extent_io_tree *tree;
 123         get_extent_t *get_extent;
 124         unsigned long bio_flags;
 125
 126         /* tells writepage not to lock the state bits for this range
 127          * it still does the unlocking
 128          */
 129         unsigned int extent_locked:1;
 130
 131         /* tells the submit_bio code to use a WRITE_SYNC */
 132         unsigned int sync_io:1;
 133 };
 134
 135 static void add_extent_changeset(struct extent_state *state, unsigned bits,
 136                                  struct extent_changeset *changeset,
 137                                  int set)
 138 {
 139         int ret;
 140
 141         if (!changeset)
 142                 return;
 143         if (set && (state->state & bits) == bits)
 144                 return;
 145         if (!set && (state->state & bits) == 0)
 146                 return;
 147         changeset->bytes_changed += state->end - state->start + 1;
 148         ret = ulist_add(changeset->range_changed, state->start, state->end,
 149                         GFP_ATOMIC);
 150         /* ENOMEM */
 151         BUG_ON(ret < 0);
 152 }
 153
 154 static noinline void flush_write_bio(void *data);
 155 static inline struct btrfs_fs_info *
 156 tree_fs_info(struct extent_io_tree *tree)
 157 {
 158         if (!tree->mapping)
 159                 return NULL;
 160         return btrfs_sb(tree->mapping->host->i_sb);
 161 }
 162
 163 int __init extent_io_init(void)
 164 {
 165         extent_state_cache = kmem_cache_create("btrfs_extent_state",
 166                         sizeof(struct extent_state), 0,
 167                         SLAB_MEM_SPREAD, NULL);
 168         if (!extent_state_cache)
 169                 return -ENOMEM;
 170
 171         extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
 172                         sizeof(struct extent_buffer), 0,
 173                         SLAB_MEM_SPREAD, NULL);
 174         if (!extent_buffer_cache)
 175                 goto free_state_cache;
 176
 177         btrfs_bioset = bioset_create(BIO_POOL_SIZE,
 178                                      offsetof(struct btrfs_io_bio, bio));
 179         if (!btrfs_bioset)
 180                 goto free_buffer_cache;
 181
 182         if (bioset_integrity_create(btrfs_bioset, BIO_POOL_SIZE))
 183                 goto free_bioset;
 184
 185         return 0;
 186
 187 free_bioset:
 188         bioset_free(btrfs_bioset);
 189         btrfs_bioset = NULL;
 190
 191 free_buffer_cache:
 192         kmem_cache_destroy(extent_buffer_cache);
 193         extent_buffer_cache = NULL;
 194
 195 free_state_cache:
 196         kmem_cache_destroy(extent_state_cache);
 197         extent_state_cache = NULL;
 198         return -ENOMEM;
 199 }
 200
 201 void extent_io_exit(void)
 202 {
 203         btrfs_leak_debug_check();
 204
 205         /*
 206          * Make sure all delayed rcu free are flushed before we
 207          * destroy caches.
 208          */
 209         rcu_barrier();
 210         kmem_cache_destroy(extent_state_cache);
 211         kmem_cache_destroy(extent_buffer_cache);
 212         if (btrfs_bioset)
 213                 bioset_free(btrfs_bioset);
 214 }
 215
 216 void extent_io_tree_init(struct extent_io_tree *tree,
 217                          struct address_space *mapping)
 218 {
 219         tree->state = RB_ROOT;
 220         tree->ops = NULL;
 221         tree->dirty_bytes = 0;
 222         spin_lock_init(&tree->lock);
 223         tree->mapping = mapping;
 224 }
 225
 226 static struct extent_state *alloc_extent_state(gfp_t mask)
 227 {
 228         struct extent_state *state;
 229
 230         state = kmem_cache_alloc(extent_state_cache, mask);
 231         if (!state)
 232                 return state;
 233         state->state = 0;
 234         state->failrec = NULL;
 235         RB_CLEAR_NODE(&state->rb_node);
 236         btrfs_leak_debug_add(&state->leak_list, &states);
 237         atomic_set(&state->refs, 1);
 238         init_waitqueue_head(&state->wq);
 239         trace_alloc_extent_state(state, mask, _RET_IP_);
 240         return state;
 241 }
 242
 243 void free_extent_state(struct extent_state *state)
 244 {
 245         if (!state)
 246                 return;
 247         if (atomic_dec_and_test(&state->refs)) {
 248                 WARN_ON(extent_state_in_tree(state));
 249                 btrfs_leak_debug_del(&state->leak_list);
 250                 trace_free_extent_state(state, _RET_IP_);
 251                 kmem_cache_free(extent_state_cache, state);
 252         }
 253 }
 254
 255 static struct rb_node *tree_insert(struct rb_root *root,
 256                                    struct rb_node *search_start,
 257                                    u64 offset,
 258                                    struct rb_node *node,
 259                                    struct rb_node ***p_in,
 260                                    struct rb_node **parent_in)
 261 {
 262         struct rb_node **p;
 263         struct rb_node *parent = NULL;
 264         struct tree_entry *entry;
 265
 266         if (p_in && parent_in) {
 267                 p = *p_in;
 268                 parent = *parent_in;
 269                 goto do_insert;
 270         }
 271
 272         p = search_start ? &search_start : &root->rb_node;
 273         while (*p) {
 274                 parent = *p;
 275                 entry = rb_entry(parent, struct tree_entry, rb_node);
 276
 277                 if (offset < entry->start)
 278                         p = &(*p)->rb_left;
 279                 else if (offset > entry->end)
 280                         p = &(*p)->rb_right;
 281                 else
 282                         return parent;
 283         }
 284
 285 do_insert:
 286         rb_link_node(node, parent, p);
 287         rb_insert_color(node, root);
 288         return NULL;
 289 }
 290
 291 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 292                                       struct rb_node **prev_ret,
 293                                       struct rb_node **next_ret,
 294                                       struct rb_node ***p_ret,
 295                                       struct rb_node **parent_ret)
 296 {
 297         struct rb_root *root = &tree->state;
 298         struct rb_node **n = &root->rb_node;
 299         struct rb_node *prev = NULL;
 300         struct rb_node *orig_prev = NULL;
 301         struct tree_entry *entry;
 302         struct tree_entry *prev_entry = NULL;
 303
 304         while (*n) {
 305                 prev = *n;
 306                 entry = rb_entry(prev, struct tree_entry, rb_node);
 307                 prev_entry = entry;
 308
 309                 if (offset < entry->start)
 310                         n = &(*n)->rb_left;
 311                 else if (offset > entry->end)
 312                         n = &(*n)->rb_right;
 313                 else
 314                         return *n;
 315         }
 316
 317         if (p_ret)
 318                 *p_ret = n;
 319         if (parent_ret)
 320                 *parent_ret = prev;
 321
 322         if (prev_ret) {
 323                 orig_prev = prev;
 324                 while (prev && offset > prev_entry->end) {
 325                         prev = rb_next(prev);
 326                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 327                 }
 328                 *prev_ret = prev;
 329                 prev = orig_prev;
 330         }
 331
 332         if (next_ret) {
 333                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 334                 while (prev && offset < prev_entry->start) {
 335                         prev = rb_prev(prev);
 336                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 337                 }
 338                 *next_ret = prev;
 339         }
 340         return NULL;
 341 }
 342
 343 static inline struct rb_node *
 344 tree_search_for_insert(struct extent_io_tree *tree,
 345                        u64 offset,
 346                        struct rb_node ***p_ret,
 347                        struct rb_node **parent_ret)
 348 {
 349         struct rb_node *prev = NULL;
 350         struct rb_node *ret;
 351
 352         ret = __etree_search(tree, offset, &prev, NULL, p_ret, parent_ret);
 353         if (!ret)
 354                 return prev;
 355         return ret;
 356 }
 357
 358 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 359                                           u64 offset)
 360 {
 361         return tree_search_for_insert(tree, offset, NULL, NULL);
 362 }
 363
 364 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
 365                      struct extent_state *other)
 366 {
 367         if (tree->ops && tree->ops->merge_extent_hook)
 368                 tree->ops->merge_extent_hook(tree->mapping->host, new,
 369                                              other);
 370 }
 371
 372 /*
 373  * utility function to look for merge candidates inside a given range.
 374  * Any extents with matching state are merged together into a single
 375  * extent in the tree.  Extents with EXTENT_IO in their state field
 376  * are not merged because the end_io handlers need to be able to do
 377  * operations on them without sleeping (or doing allocations/splits).
 378  *
 379  * This should be called with the tree lock held.
 380  */
 381 static void merge_state(struct extent_io_tree *tree,
 382                         struct extent_state *state)
 383 {
 384         struct extent_state *other;
 385         struct rb_node *other_node;
 386
 387         if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 388                 return;
 389
 390         other_node = rb_prev(&state->rb_node);
 391         if (other_node) {
 392                 other = rb_entry(other_node, struct extent_state, rb_node);
 393                 if (other->end == state->start - 1 &&
 394                     other->state == state->state) {
 395                         merge_cb(tree, state, other);
 396                         state->start = other->start;
 397                         rb_erase(&other->rb_node, &tree->state);
 398                         RB_CLEAR_NODE(&other->rb_node);
 399                         free_extent_state(other);
 400                 }
 401         }
 402         other_node = rb_next(&state->rb_node);
 403         if (other_node) {
 404                 other = rb_entry(other_node, struct extent_state, rb_node);
 405                 if (other->start == state->end + 1 &&
 406                     other->state == state->state) {
 407                         merge_cb(tree, state, other);
 408                         state->end = other->end;
 409                         rb_erase(&other->rb_node, &tree->state);
 410                         RB_CLEAR_NODE(&other->rb_node);
 411                         free_extent_state(other);
 412                 }
 413         }
 414 }
 415
 416 static void set_state_cb(struct extent_io_tree *tree,
 417                          struct extent_state *state, unsigned *bits)
 418 {
 419         if (tree->ops && tree->ops->set_bit_hook)
 420                 tree->ops->set_bit_hook(tree->mapping->host, state, bits);
 421 }
 422
 423 static void clear_state_cb(struct extent_io_tree *tree,
 424                            struct extent_state *state, unsigned *bits)
 425 {
 426         if (tree->ops && tree->ops->clear_bit_hook)
 427                 tree->ops->clear_bit_hook(tree->mapping->host, state, bits);
 428 }
 429
 430 static void set_state_bits(struct extent_io_tree *tree,
 431                            struct extent_state *state, unsigned *bits,
 432                            struct extent_changeset *changeset);
 433
 434 /*
 435  * insert an extent_state struct into the tree.  'bits' are set on the
 436  * struct before it is inserted.
 437  *
 438  * This may return -EEXIST if the extent is already there, in which case the
 439  * state struct is freed.
 440  *
 441  * The tree lock is not taken internally.  This is a utility function and
 442  * probably isn't what you want to call (see set/clear_extent_bit).
 443  */
 444 static int insert_state(struct extent_io_tree *tree,
 445                         struct extent_state *state, u64 start, u64 end,
 446                         struct rb_node ***p,
 447                         struct rb_node **parent,
 448                         unsigned *bits, struct extent_changeset *changeset)
 449 {
 450         struct rb_node *node;
 451
 452         if (end < start)
 453                 WARN(1, KERN_ERR "BTRFS: end < start %llu %llu\n",
 454                        end, start);
 455         state->start = start;
 456         state->end = end;
 457
 458         set_state_bits(tree, state, bits, changeset);
 459
 460         node = tree_insert(&tree->state, NULL, end, &state->rb_node, p, parent);
 461         if (node) {
 462                 struct extent_state *found;
 463                 found = rb_entry(node, struct extent_state, rb_node);
 464                 printk(KERN_ERR "BTRFS: found node %llu %llu on insert of "
 465                        "%llu %llu\n",
 466                        found->start, found->end, start, end);
 467                 return -EEXIST;
 468         }
 469         merge_state(tree, state);
 470         return 0;
 471 }
 472
 473 static void split_cb(struct extent_io_tree *tree, struct extent_state *orig,
 474                      u64 split)
 475 {
 476         if (tree->ops && tree->ops->split_extent_hook)
 477                 tree->ops->split_extent_hook(tree->mapping->host, orig, split);
 478 }
 479
 480 /*
 481  * split a given extent state struct in two, inserting the preallocated
 482  * struct 'prealloc' as the newly created second half.  'split' indicates an
 483  * offset inside 'orig' where it should be split.
 484  *
 485  * Before calling,
 486  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
 487  * are two extent state structs in the tree:
 488  * prealloc: [orig->start, split - 1]
 489  * orig: [ split, orig->end ]
 490  *
 491  * The tree locks are not taken by this function. They need to be held
 492  * by the caller.
 493  */
 494 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 495                        struct extent_state *prealloc, u64 split)
 496 {
 497         struct rb_node *node;
 498
 499         split_cb(tree, orig, split);
 500
 501         prealloc->start = orig->start;
 502         prealloc->end = split - 1;
 503         prealloc->state = orig->state;
 504         orig->start = split;
 505
 506         node = tree_insert(&tree->state, &orig->rb_node, prealloc->end,
 507                            &prealloc->rb_node, NULL, NULL);
 508         if (node) {
 509                 free_extent_state(prealloc);
 510                 return -EEXIST;
 511         }
 512         return 0;
 513 }
 514
 515 static struct extent_state *next_state(struct extent_state *state)
 516 {
 517         struct rb_node *next = rb_next(&state->rb_node);
 518         if (next)
 519                 return rb_entry(next, struct extent_state, rb_node);
 520         else
 521                 return NULL;
 522 }
 523
 524 /*
 525  * utility function to clear some bits in an extent state struct.
 526  * it will optionally wake up any one waiting on this state (wake == 1).
 527  *
 528  * If no bits are set on the state struct after clearing things, the
 529  * struct is freed and removed from the tree
 530  */
 531 static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
 532                                             struct extent_state *state,
 533                                             unsigned *bits, int wake,
 534                                             struct extent_changeset *changeset)
 535 {
 536         struct extent_state *next;
 537         unsigned bits_to_clear = *bits & ~EXTENT_CTLBITS;
 538
 539         if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 540                 u64 range = state->end - state->start + 1;
 541                 WARN_ON(range > tree->dirty_bytes);
 542                 tree->dirty_bytes -= range;
 543         }
 544         clear_state_cb(tree, state, bits);
 545         add_extent_changeset(state, bits_to_clear, changeset, 0);
 546         state->state &= ~bits_to_clear;
 547         if (wake)
 548                 wake_up(&state->wq);
 549         if (state->state == 0) {
 550                 next = next_state(state);
 551                 if (extent_state_in_tree(state)) {
 552                         rb_erase(&state->rb_node, &tree->state);
 553                         RB_CLEAR_NODE(&state->rb_node);
 554                         free_extent_state(state);
 555                 } else {
 556                         WARN_ON(1);
 557                 }
 558         } else {
 559                 merge_state(tree, state);
 560                 next = next_state(state);
 561         }
 562         return next;
 563 }
 564
 565 static struct extent_state *
 566 alloc_extent_state_atomic(struct extent_state *prealloc)
 567 {
 568         if (!prealloc)
 569                 prealloc = alloc_extent_state(GFP_ATOMIC);
 570
 571         return prealloc;
 572 }
 573
 574 static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
 575 {
 576         btrfs_panic(tree_fs_info(tree), err, "Locking error: "
 577                     "Extent tree was modified by another "
 578                     "thread while locked.");
 579 }
 580
 581 /*
 582  * clear some bits on a range in the tree.  This may require splitting
 583  * or inserting elements in the tree, so the gfp mask is used to
 584  * indicate which allocations or sleeping are allowed.
 585  *
 586  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 587  * the given range from the tree regardless of state (ie for truncate).
 588  *
 589  * the range [start, end] is inclusive.
 590  *
 591  * This takes the tree lock, and returns 0 on success and < 0 on error.
 592  */
 593 static int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 594                               unsigned bits, int wake, int delete,
 595                               struct extent_state **cached_state,
 596                               gfp_t mask, struct extent_changeset *changeset)
 597 {
 598         struct extent_state *state;
 599         struct extent_state *cached;
 600         struct extent_state *prealloc = NULL;
 601         struct rb_node *node;
 602         u64 last_end;
 603         int err;
 604         int clear = 0;
 605
 606         btrfs_debug_check_extent_io_range(tree, start, end);
 607
 608         if (bits & EXTENT_DELALLOC)
 609                 bits |= EXTENT_NORESERVE;
 610
 611         if (delete)
 612                 bits |= ~EXTENT_CTLBITS;
 613         bits |= EXTENT_FIRST_DELALLOC;
 614
 615         if (bits & (EXTENT_IOBITS | EXTENT_BOUNDARY))
 616                 clear = 1;
 617 again:
 618         if (!prealloc && gfpflags_allow_blocking(mask)) {
 619                 /*
 620                  * Don't care for allocation failure here because we might end
 621                  * up not needing the pre-allocated extent state at all, which
 622                  * is the case if we only have in the tree extent states that
 623                  * cover our input range and don't cover too any other range.
 624                  * If we end up needing a new extent state we allocate it later.
 625                  */
 626                 prealloc = alloc_extent_state(mask);
 627         }
 628
 629         spin_lock(&tree->lock);
 630         if (cached_state) {
 631                 cached = *cached_state;
 632
 633                 if (clear) {
 634                         *cached_state = NULL;
 635                         cached_state = NULL;
 636                 }
 637
 638                 if (cached && extent_state_in_tree(cached) &&
 639                     cached->start <= start && cached->end > start) {
 640                         if (clear)
 641                                 atomic_dec(&cached->refs);
 642                         state = cached;
 643                         goto hit_next;
 644                 }
 645                 if (clear)
 646                         free_extent_state(cached);
 647         }
 648         /*
 649          * this search will find the extents that end after
 650          * our range starts
 651          */
 652         node = tree_search(tree, start);
 653         if (!node)
 654                 goto out;
 655         state = rb_entry(node, struct extent_state, rb_node);
 656 hit_next:
 657         if (state->start > end)
 658                 goto out;
 659         WARN_ON(state->end < start);
 660         last_end = state->end;
 661
 662         /* the state doesn't have the wanted bits, go ahead */
 663         if (!(state->state & bits)) {
 664                 state = next_state(state);
 665                 goto next;
 666         }
 667
 668         /*
 669          *     | ---- desired range ---- |
 670          *  | state | or
 671          *  | ------------- state -------------- |
 672          *
 673          * We need to split the extent we found, and may flip
 674          * bits on second half.
 675          *
 676          * If the extent we found extends past our range, we
 677          * just split and search again.  It'll get split again
 678          * the next time though.
 679          *
 680          * If the extent we found is inside our range, we clear
 681          * the desired bit on it.
 682          */
 683
 684         if (state->start < start) {
 685                 prealloc = alloc_extent_state_atomic(prealloc);
 686                 BUG_ON(!prealloc);
 687                 err = split_state(tree, state, prealloc, start);
 688                 if (err)
 689                         extent_io_tree_panic(tree, err);
 690
 691                 prealloc = NULL;
 692                 if (err)
 693                         goto out;
 694                 if (state->end <= end) {
 695                         state = clear_state_bit(tree, state, &bits, wake,
 696                                                 changeset);
 697                         goto next;
 698                 }
 699                 goto search_again;
 700         }
 701         /*
 702          * | ---- desired range ---- |
 703          *                        | state |
 704          * We need to split the extent, and clear the bit
 705          * on the first half
 706          */
 707         if (state->start <= end && state->end > end) {
 708                 prealloc = alloc_extent_state_atomic(prealloc);
 709                 BUG_ON(!prealloc);
 710                 err = split_state(tree, state, prealloc, end + 1);
 711                 if (err)
 712                         extent_io_tree_panic(tree, err);
 713
 714                 if (wake)
 715                         wake_up(&state->wq);
 716
 717                 clear_state_bit(tree, prealloc, &bits, wake, changeset);
 718
 719                 prealloc = NULL;
 720                 goto out;
 721         }
 722
 723         state = clear_state_bit(tree, state, &bits, wake, changeset);
 724 next:
 725         if (last_end == (u64)-1)
 726                 goto out;
 727         start = last_end + 1;
 728         if (start <= end && state && !need_resched())
 729                 goto hit_next;
 730
 731 search_again:
 732         if (start > end)
 733                 goto out;
 734         spin_unlock(&tree->lock);
 735         if (gfpflags_allow_blocking(mask))
 736                 cond_resched();
 737         goto again;
 738
 739 out:
 740         spin_unlock(&tree->lock);
 741         if (prealloc)
 742                 free_extent_state(prealloc);
 743
 744         return 0;
 745
 746 }
 747
 748 static void wait_on_state(struct extent_io_tree *tree,
 749                           struct extent_state *state)
 750                 __releases(tree->lock)
 751                 __acquires(tree->lock)
 752 {
 753         DEFINE_WAIT(wait);
 754         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 755         spin_unlock(&tree->lock);
 756         schedule();
 757         spin_lock(&tree->lock);
 758         finish_wait(&state->wq, &wait);
 759 }
 760
 761 /*
 762  * waits for one or more bits to clear on a range in the state tree.
 763  * The range [start, end] is inclusive.
 764  * The tree lock is taken by this function
 765  */
 766 static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 767                             unsigned long bits)
 768 {
 769         struct extent_state *state;
 770         struct rb_node *node;
 771
 772         btrfs_debug_check_extent_io_range(tree, start, end);
 773
 774         spin_lock(&tree->lock);
 775 again:
 776         while (1) {
 777                 /*
 778                  * this search will find all the extents that end after
 779                  * our range starts
 780                  */
 781                 node = tree_search(tree, start);
 782 process_node:
 783                 if (!node)
 784                         break;
 785
 786                 state = rb_entry(node, struct extent_state, rb_node);
 787
 788                 if (state->start > end)
 789                         goto out;
 790
 791                 if (state->state & bits) {
 792                         start = state->start;
 793                         atomic_inc(&state->refs);
 794                         wait_on_state(tree, state);
 795                         free_extent_state(state);
 796                         goto again;
 797                 }
 798                 start = state->end + 1;
 799
 800                 if (start > end)
 801                         break;
 802
 803                 if (!cond_resched_lock(&tree->lock)) {
 804                         node = rb_next(node);
 805                         goto process_node;
 806                 }
 807         }
 808 out:
 809         spin_unlock(&tree->lock);
 810 }
 811
 812 static void set_state_bits(struct extent_io_tree *tree,
 813                            struct extent_state *state,
 814                            unsigned *bits, struct extent_changeset *changeset)
 815 {
 816         unsigned bits_to_set = *bits & ~EXTENT_CTLBITS;
 817
 818         set_state_cb(tree, state, bits);
 819         if ((bits_to_set & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 820                 u64 range = state->end - state->start + 1;
 821                 tree->dirty_bytes += range;
 822         }
 823         add_extent_changeset(state, bits_to_set, changeset, 1);
 824         state->state |= bits_to_set;
 825 }
 826
 827 static void cache_state_if_flags(struct extent_state *state,
 828                                  struct extent_state **cached_ptr,
 829                                  unsigned flags)
 830 {
 831         if (cached_ptr && !(*cached_ptr)) {
 832                 if (!flags || (state->state & flags)) {
 833                         *cached_ptr = state;
 834                         atomic_inc(&state->refs);
 835                 }
 836         }
 837 }
 838
 839 static void cache_state(struct extent_state *state,
 840                         struct extent_state **cached_ptr)
 841 {
 842         return cache_state_if_flags(state, cached_ptr,
 843                                     EXTENT_IOBITS | EXTENT_BOUNDARY);
 844 }
 845
 846 /*
 847  * set some bits on a range in the tree.  This may require allocations or
 848  * sleeping, so the gfp mask is used to indicate what is allowed.
 849  *
 850  * If any of the exclusive bits are set, this will fail with -EEXIST if some
 851  * part of the range already has the desired bits set.  The start of the
 852  * existing range is returned in failed_start in this case.
 853  *
 854  * [start, end] is inclusive This takes the tree lock.
 855  */
 856
 857 static int __must_check
 858 __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 859                  unsigned bits, unsigned exclusive_bits,
 860                  u64 *failed_start, struct extent_state **cached_state,
 861                  gfp_t mask, struct extent_changeset *changeset)
 862 {
 863         struct extent_state *state;
 864         struct extent_state *prealloc = NULL;
 865         struct rb_node *node;
 866         struct rb_node **p;
 867         struct rb_node *parent;
 868         int err = 0;
 869         u64 last_start;
 870         u64 last_end;
 871
 872         btrfs_debug_check_extent_io_range(tree, start, end);
 873
 874         bits |= EXTENT_FIRST_DELALLOC;
 875 again:
 876         if (!prealloc && gfpflags_allow_blocking(mask)) {
 877                 /*
 878                  * Don't care for allocation failure here because we might end
 879                  * up not needing the pre-allocated extent state at all, which
 880                  * is the case if we only have in the tree extent states that
 881                  * cover our input range and don't cover too any other range.
 882                  * If we end up needing a new extent state we allocate it later.
 883                  */
 884                 prealloc = alloc_extent_state(mask);
 885         }
 886
 887         spin_lock(&tree->lock);
 888         if (cached_state && *cached_state) {
 889                 state = *cached_state;
 890                 if (state->start <= start && state->end > start &&
 891                     extent_state_in_tree(state)) {
 892                         node = &state->rb_node;
 893                         goto hit_next;
 894                 }
 895         }
 896         /*
 897          * this search will find all the extents that end after
 898          * our range starts.
 899          */
 900         node = tree_search_for_insert(tree, start, &p, &parent);
 901         if (!node) {
 902                 prealloc = alloc_extent_state_atomic(prealloc);
 903                 BUG_ON(!prealloc);
 904                 err = insert_state(tree, prealloc, start, end,
 905                                    &p, &parent, &bits, changeset);
 906                 if (err)
 907                         extent_io_tree_panic(tree, err);
 908
 909                 cache_state(prealloc, cached_state);
 910                 prealloc = NULL;
 911                 goto out;
 912         }
 913         state = rb_entry(node, struct extent_state, rb_node);
 914 hit_next:
 915         last_start = state->start;
 916         last_end = state->end;
 917
 918         /*
 919          * | ---- desired range ---- |
 920          * | state |
 921          *
 922          * Just lock what we found and keep going
 923          */
 924         if (state->start == start && state->end <= end) {
 925                 if (state->state & exclusive_bits) {
 926                         *failed_start = state->start;
 927                         err = -EEXIST;
 928                         goto out;
 929                 }
 930
 931                 set_state_bits(tree, state, &bits, changeset);
 932                 cache_state(state, cached_state);
 933                 merge_state(tree, state);
 934                 if (last_end == (u64)-1)
 935                         goto out;
 936                 start = last_end + 1;
 937                 state = next_state(state);
 938                 if (start < end && state && state->start == start &&
 939                     !need_resched())
 940                         goto hit_next;
 941                 goto search_again;
 942         }
 943
 944         /*
 945          *     | ---- desired range ---- |
 946          * | state |
 947          *   or
 948          * | ------------- state -------------- |
 949          *
 950          * We need to split the extent we found, and may flip bits on
 951          * second half.
 952          *
 953          * If the extent we found extends past our
 954          * range, we just split and search again.  It'll get split
 955          * again the next time though.
 956          *
 957          * If the extent we found is inside our range, we set the
 958          * desired bit on it.
 959          */
 960         if (state->start < start) {
 961                 if (state->state & exclusive_bits) {
 962                         *failed_start = start;
 963                         err = -EEXIST;
 964                         goto out;
 965                 }
 966
 967                 prealloc = alloc_extent_state_atomic(prealloc);
 968                 BUG_ON(!prealloc);
 969                 err = split_state(tree, state, prealloc, start);
 970                 if (err)
 971                         extent_io_tree_panic(tree, err);
 972
 973                 prealloc = NULL;
 974                 if (err)
 975                         goto out;
 976                 if (state->end <= end) {
 977                         set_state_bits(tree, state, &bits, changeset);
 978                         cache_state(state, cached_state);
 979                         merge_state(tree, state);
 980                         if (last_end == (u64)-1)
 981                                 goto out;
 982                         start = last_end + 1;
 983                         state = next_state(state);
 984                         if (start < end && state && state->start == start &&
 985                             !need_resched())
 986                                 goto hit_next;
 987                 }
 988                 goto search_again;
 989         }
 990         /*
 991          * | ---- desired range ---- |
 992          *     | state | or               | state |
 993          *
 994          * There's a hole, we need to insert something in it and
 995          * ignore the extent we found.
 996          */
 997         if (state->start > start) {
 998                 u64 this_end;
 999                 if (end < last_start)
1000                         this_end = end;
1001                 else
1002                         this_end = last_start - 1;
1003
1004                 prealloc = alloc_extent_state_atomic(prealloc);
1005                 BUG_ON(!prealloc);
1006
1007                 /*
1008                  * Avoid to free 'prealloc' if it can be merged with
1009                  * the later extent.
1010                  */
1011                 err = insert_state(tree, prealloc, start, this_end,
1012                                    NULL, NULL, &bits, changeset);
1013                 if (err)
1014                         extent_io_tree_panic(tree, err);
1015
1016                 cache_state(prealloc, cached_state);
1017                 prealloc = NULL;
1018                 start = this_end + 1;
1019                 goto search_again;
1020         }
1021         /*
1022          * | ---- desired range ---- |
1023          *                        | state |
1024          * We need to split the extent, and set the bit
1025          * on the first half
1026          */
1027         if (state->start <= end && state->end > end) {
1028                 if (state->state & exclusive_bits) {
1029                         *failed_start = start;
1030                         err = -EEXIST;
1031                         goto out;
1032                 }
1033
1034                 prealloc = alloc_extent_state_atomic(prealloc);
1035                 BUG_ON(!prealloc);
1036                 err = split_state(tree, state, prealloc, end + 1);
1037                 if (err)
1038                         extent_io_tree_panic(tree, err);
1039
1040                 set_state_bits(tree, prealloc, &bits, changeset);
1041                 cache_state(prealloc, cached_state);
1042                 merge_state(tree, prealloc);
1043                 prealloc = NULL;
1044                 goto out;
1045         }
1046
1047 search_again:
1048         if (start > end)
1049                 goto out;
1050         spin_unlock(&tree->lock);
1051         if (gfpflags_allow_blocking(mask))
1052                 cond_resched();
1053         goto again;
1054
1055 out:
1056         spin_unlock(&tree->lock);
1057         if (prealloc)
1058                 free_extent_state(prealloc);
1059
1060         return err;
1061
1062 }
1063
1064 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1065                    unsigned bits, u64 * failed_start,
1066                    struct extent_state **cached_state, gfp_t mask)
1067 {
1068         return __set_extent_bit(tree, start, end, bits, 0, failed_start,
1069                                 cached_state, mask, NULL);
1070 }
1071
1072
1073 /**
1074  * convert_extent_bit - convert all bits in a given range from one bit to
1075  *                      another
1076  * @tree:       the io tree to search
1077  * @start:      the start offset in bytes
1078  * @end:        the end offset in bytes (inclusive)
1079  * @bits:       the bits to set in this range
1080  * @clear_bits: the bits to clear in this range
1081  * @cached_state:       state that we're going to cache
1082  *
1083  * This will go through and set bits for the given range.  If any states exist
1084  * already in this range they are set with the given bit and cleared of the
1085  * clear_bits.  This is only meant to be used by things that are mergeable, ie
1086  * converting from say DELALLOC to DIRTY.  This is not meant to be used with
1087  * boundary bits like LOCK.
1088  *
1089  * All allocations are done with GFP_NOFS.
1090  */
1091 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1092                        unsigned bits, unsigned clear_bits,
1093                        struct extent_state **cached_state)
1094 {
1095         struct extent_state *state;
1096         struct extent_state *prealloc = NULL;
1097         struct rb_node *node;
1098         struct rb_node **p;
1099         struct rb_node *parent;
1100         int err = 0;
1101         u64 last_start;
1102         u64 last_end;
1103         bool first_iteration = true;
1104
1105         btrfs_debug_check_extent_io_range(tree, start, end);
1106
1107 again:
1108         if (!prealloc) {
1109                 /*
1110                  * Best effort, don't worry if extent state allocation fails
1111                  * here for the first iteration. We might have a cached state
1112                  * that matches exactly the target range, in which case no
1113                  * extent state allocations are needed. We'll only know this
1114                  * after locking the tree.
1115                  */
1116                 prealloc = alloc_extent_state(GFP_NOFS);
1117                 if (!prealloc && !first_iteration)
1118                         return -ENOMEM;
1119         }
1120
1121         spin_lock(&tree->lock);
1122         if (cached_state && *cached_state) {
1123                 state = *cached_state;
1124                 if (state->start <= start && state->end > start &&
1125                     extent_state_in_tree(state)) {
1126                         node = &state->rb_node;
1127                         goto hit_next;
1128                 }
1129         }
1130
1131         /*
1132          * this search will find all the extents that end after
1133          * our range starts.
1134          */
1135         node = tree_search_for_insert(tree, start, &p, &parent);
1136         if (!node) {
1137                 prealloc = alloc_extent_state_atomic(prealloc);
1138                 if (!prealloc) {
1139                         err = -ENOMEM;
1140                         goto out;
1141                 }
1142                 err = insert_state(tree, prealloc, start, end,
1143                                    &p, &parent, &bits, NULL);
1144                 if (err)
1145                         extent_io_tree_panic(tree, err);
1146                 cache_state(prealloc, cached_state);
1147                 prealloc = NULL;
1148                 goto out;
1149         }
1150         state = rb_entry(node, struct extent_state, rb_node);
1151 hit_next:
1152         last_start = state->start;
1153         last_end = state->end;
1154
1155         /*
1156          * | ---- desired range ---- |
1157          * | state |
1158          *
1159          * Just lock what we found and keep going
1160          */
1161         if (state->start == start && state->end <= end) {
1162                 set_state_bits(tree, state, &bits, NULL);
1163                 cache_state(state, cached_state);
1164                 state = clear_state_bit(tree, state, &clear_bits, 0, NULL);
1165                 if (last_end == (u64)-1)
1166                         goto out;
1167                 start = last_end + 1;
1168                 if (start < end && state && state->start == start &&
1169                     !need_resched())
1170                         goto hit_next;
1171                 goto search_again;
1172         }
1173
1174         /*
1175          *     | ---- desired range ---- |
1176          * | state |
1177          *   or
1178          * | ------------- state -------------- |
1179          *
1180          * We need to split the extent we found, and may flip bits on
1181          * second half.
1182          *
1183          * If the extent we found extends past our
1184          * range, we just split and search again.  It'll get split
1185          * again the next time though.
1186          *
1187          * If the extent we found is inside our range, we set the
1188          * desired bit on it.
1189          */
1190         if (state->start < start) {
1191                 prealloc = alloc_extent_state_atomic(prealloc);
1192                 if (!prealloc) {
1193                         err = -ENOMEM;
1194                         goto out;
1195                 }
1196                 err = split_state(tree, state, prealloc, start);
1197                 if (err)
1198                         extent_io_tree_panic(tree, err);
1199                 prealloc = NULL;
1200                 if (err)
1201                         goto out;
1202                 if (state->end <= end) {
1203                         set_state_bits(tree, state, &bits, NULL);
1204                         cache_state(state, cached_state);
1205                         state = clear_state_bit(tree, state, &clear_bits, 0,
1206                                                 NULL);
1207                         if (last_end == (u64)-1)
1208                                 goto out;
1209                         start = last_end + 1;
1210                         if (start < end && state && state->start == start &&
1211                             !need_resched())
1212                                 goto hit_next;
1213                 }
1214                 goto search_again;
1215         }
1216         /*
1217          * | ---- desired range ---- |
1218          *     | state | or               | state |
1219          *
1220          * There's a hole, we need to insert something in it and
1221          * ignore the extent we found.
1222          */
1223         if (state->start > start) {
1224                 u64 this_end;
1225                 if (end < last_start)
1226                         this_end = end;
1227                 else
1228                         this_end = last_start - 1;
1229
1230                 prealloc = alloc_extent_state_atomic(prealloc);
1231                 if (!prealloc) {
1232                         err = -ENOMEM;
1233                         goto out;
1234                 }
1235
1236                 /*
1237                  * Avoid to free 'prealloc' if it can be merged with
1238                  * the later extent.
1239                  */
1240                 err = insert_state(tree, prealloc, start, this_end,
1241                                    NULL, NULL, &bits, NULL);
1242                 if (err)
1243                         extent_io_tree_panic(tree, err);
1244                 cache_state(prealloc, cached_state);
1245                 prealloc = NULL;
1246                 start = this_end + 1;
1247                 goto search_again;
1248         }
1249         /*
1250          * | ---- desired range ---- |
1251          *                        | state |
1252          * We need to split the extent, and set the bit
1253          * on the first half
1254          */
1255         if (state->start <= end && state->end > end) {
1256                 prealloc = alloc_extent_state_atomic(prealloc);
1257                 if (!prealloc) {
1258                         err = -ENOMEM;
1259                         goto out;
1260                 }
1261
1262                 err = split_state(tree, state, prealloc, end + 1);
1263                 if (err)
1264                         extent_io_tree_panic(tree, err);
1265
1266                 set_state_bits(tree, prealloc, &bits, NULL);
1267                 cache_state(prealloc, cached_state);
1268                 clear_state_bit(tree, prealloc, &clear_bits, 0, NULL);
1269                 prealloc = NULL;
1270                 goto out;
1271         }
1272
1273 search_again:
1274         if (start > end)
1275                 goto out;
1276         spin_unlock(&tree->lock);
1277         cond_resched();
1278         first_iteration = false;
1279         goto again;
1280
1281 out:
1282         spin_unlock(&tree->lock);
1283         if (prealloc)
1284                 free_extent_state(prealloc);
1285
1286         return err;
1287 }
1288
1289 /* wrappers around set/clear extent bit */
1290 int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1291                            unsigned bits, struct extent_changeset *changeset)
1292 {
1293         /*
1294          * We don't support EXTENT_LOCKED yet, as current changeset will
1295          * record any bits changed, so for EXTENT_LOCKED case, it will
1296          * either fail with -EEXIST or changeset will record the whole
1297          * range.
1298          */
1299         BUG_ON(bits & EXTENT_LOCKED);
1300
1301         return __set_extent_bit(tree, start, end, bits, 0, NULL, NULL, GFP_NOFS,
1302                                 changeset);
1303 }
1304
1305 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1306                      unsigned bits, int wake, int delete,
1307                      struct extent_state **cached, gfp_t mask)
1308 {
1309         return __clear_extent_bit(tree, start, end, bits, wake, delete,
1310                                   cached, mask, NULL);
1311 }
1312
1313 int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1314                 unsigned bits, struct extent_changeset *changeset)
1315 {
1316         /*
1317          * Don't support EXTENT_LOCKED case, same reason as
1318          * set_record_extent_bits().
1319          */
1320         BUG_ON(bits & EXTENT_LOCKED);
1321
1322         return __clear_extent_bit(tree, start, end, bits, 0, 0, NULL, GFP_NOFS,
1323                                   changeset);
1324 }
1325
1326 /*
1327  * either insert or lock state struct between start and end use mask to tell
1328  * us if waiting is desired.
1329  */
1330 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1331                      struct extent_state **cached_state)
1332 {
1333         int err;
1334         u64 failed_start;
1335
1336         while (1) {
1337                 err = __set_extent_bit(tree, start, end, EXTENT_LOCKED,
1338                                        EXTENT_LOCKED, &failed_start,
1339                                        cached_state, GFP_NOFS, NULL);
1340                 if (err == -EEXIST) {
1341                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1342                         start = failed_start;
1343                 } else
1344                         break;
1345                 WARN_ON(start > end);
1346         }
1347         return err;
1348 }
1349
1350 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1351 {
1352         int err;
1353         u64 failed_start;
1354
1355         err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1356                                &failed_start, NULL, GFP_NOFS, NULL);
1357         if (err == -EEXIST) {
1358                 if (failed_start > start)
1359                         clear_extent_bit(tree, start, failed_start - 1,
1360                                          EXTENT_LOCKED, 1, 0, NULL, GFP_NOFS);
1361                 return 0;
1362         }
1363         return 1;
1364 }
1365
1366 void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
1367 {
1368         unsigned long index = start >> PAGE_SHIFT;
1369         unsigned long end_index = end >> PAGE_SHIFT;
1370         struct page *page;
1371
1372         while (index <= end_index) {
1373                 page = find_get_page(inode->i_mapping, index);
1374                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1375                 clear_page_dirty_for_io(page);
1376                 put_page(page);
1377                 index++;
1378         }
1379 }
1380
1381 void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
1382 {
1383         unsigned long index = start >> PAGE_SHIFT;
1384         unsigned long end_index = end >> PAGE_SHIFT;
1385         struct page *page;
1386
1387         while (index <= end_index) {
1388                 page = find_get_page(inode->i_mapping, index);
1389                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1390                 __set_page_dirty_nobuffers(page);
1391                 account_page_redirty(page);
1392                 put_page(page);
1393                 index++;
1394         }
1395 }
1396
1397 /*
1398  * helper function to set both pages and extents in the tree writeback
1399  */
1400 static void set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1401 {
1402         unsigned long index = start >> PAGE_SHIFT;
1403         unsigned long end_index = end >> PAGE_SHIFT;
1404         struct page *page;
1405
1406         while (index <= end_index) {
1407                 page = find_get_page(tree->mapping, index);
1408                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1409                 set_page_writeback(page);
1410                 put_page(page);
1411                 index++;
1412         }
1413 }
1414
1415 /* find the first state struct with 'bits' set after 'start', and
1416  * return it.  tree->lock must be held.  NULL will returned if
1417  * nothing was found after 'start'
1418  */
1419 static struct extent_state *
1420 find_first_extent_bit_state(struct extent_io_tree *tree,
1421                             u64 start, unsigned bits)
1422 {
1423         struct rb_node *node;
1424         struct extent_state *state;
1425
1426         /*
1427          * this search will find all the extents that end after
1428          * our range starts.
1429          */
1430         node = tree_search(tree, start);
1431         if (!node)
1432                 goto out;
1433
1434         while (1) {
1435                 state = rb_entry(node, struct extent_state, rb_node);
1436                 if (state->end >= start && (state->state & bits))
1437                         return state;
1438
1439                 node = rb_next(node);
1440                 if (!node)
1441                         break;
1442         }
1443 out:
1444         return NULL;
1445 }
1446
1447 /*
1448  * find the first offset in the io tree with 'bits' set. zero is
1449  * returned if we find something, and *start_ret and *end_ret are
1450  * set to reflect the state struct that was found.
1451  *
1452  * If nothing was found, 1 is returned. If found something, return 0.
1453  */
1454 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1455                           u64 *start_ret, u64 *end_ret, unsigned bits,
1456                           struct extent_state **cached_state)
1457 {
1458         struct extent_state *state;
1459         struct rb_node *n;
1460         int ret = 1;
1461
1462         spin_lock(&tree->lock);
1463         if (cached_state && *cached_state) {
1464                 state = *cached_state;
1465                 if (state->end == start - 1 && extent_state_in_tree(state)) {
1466                         n = rb_next(&state->rb_node);
1467                         while (n) {
1468                                 state = rb_entry(n, struct extent_state,
1469                                                  rb_node);
1470                                 if (state->state & bits)
1471                                         goto got_it;
1472                                 n = rb_next(n);
1473                         }
1474                         free_extent_state(*cached_state);
1475                         *cached_state = NULL;
1476                         goto out;
1477                 }
1478                 free_extent_state(*cached_state);
1479                 *cached_state = NULL;
1480         }
1481
1482         state = find_first_extent_bit_state(tree, start, bits);
1483 got_it:
1484         if (state) {
1485                 cache_state_if_flags(state, cached_state, 0);
1486                 *start_ret = state->start;
1487                 *end_ret = state->end;
1488                 ret = 0;
1489         }
1490 out:
1491         spin_unlock(&tree->lock);
1492         return ret;
1493 }
1494
1495 /*
1496  * find a contiguous range of bytes in the file marked as delalloc, not
1497  * more than 'max_bytes'.  start and end are used to return the range,
1498  *
1499  * 1 is returned if we find something, 0 if nothing was in the tree
1500  */
1501 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1502                                         u64 *start, u64 *end, u64 max_bytes,
1503                                         struct extent_state **cached_state)
1504 {
1505         struct rb_node *node;
1506         struct extent_state *state;
1507         u64 cur_start = *start;
1508         u64 found = 0;
1509         u64 total_bytes = 0;
1510
1511         spin_lock(&tree->lock);
1512
1513         /*
1514          * this search will find all the extents that end after
1515          * our range starts.
1516          */
1517         node = tree_search(tree, cur_start);
1518         if (!node) {
1519                 if (!found)
1520                         *end = (u64)-1;
1521                 goto out;
1522         }
1523
1524         while (1) {
1525                 state = rb_entry(node, struct extent_state, rb_node);
1526                 if (found && (state->start != cur_start ||
1527                               (state->state & EXTENT_BOUNDARY))) {
1528                         goto out;
1529                 }
1530                 if (!(state->state & EXTENT_DELALLOC)) {
1531                         if (!found)
1532                                 *end = state->end;
1533                         goto out;
1534                 }
1535                 if (!found) {
1536                         *start = state->start;
1537                         *cached_state = state;
1538                         atomic_inc(&state->refs);
1539                 }
1540                 found++;
1541                 *end = state->end;
1542                 cur_start = state->end + 1;
1543                 node = rb_next(node);
1544                 total_bytes += state->end - state->start + 1;
1545                 if (total_bytes >= max_bytes)
1546                         break;
1547                 if (!node)
1548                         break;
1549         }
1550 out:
1551         spin_unlock(&tree->lock);
1552         return found;
1553 }
1554
1555 static noinline void __unlock_for_delalloc(struct inode *inode,
1556                                            struct page *locked_page,
1557                                            u64 start, u64 end)
1558 {
1559         int ret;
1560         struct page *pages[16];
1561         unsigned long index = start >> PAGE_SHIFT;
1562         unsigned long end_index = end >> PAGE_SHIFT;
1563         unsigned long nr_pages = end_index - index + 1;
1564         int i;
1565
1566         if (index == locked_page->index && end_index == index)
1567                 return;
1568
1569         while (nr_pages > 0) {
1570                 ret = find_get_pages_contig(inode->i_mapping, index,
1571                                      min_t(unsigned long, nr_pages,
1572                                      ARRAY_SIZE(pages)), pages);
1573                 for (i = 0; i < ret; i++) {
1574                         if (pages[i] != locked_page)
1575                                 unlock_page(pages[i]);
1576                         put_page(pages[i]);
1577                 }
1578                 nr_pages -= ret;
1579                 index += ret;
1580                 cond_resched();
1581         }
1582 }
1583
1584 static noinline int lock_delalloc_pages(struct inode *inode,
1585                                         struct page *locked_page,
1586                                         u64 delalloc_start,
1587                                         u64 delalloc_end)
1588 {
1589         unsigned long index = delalloc_start >> PAGE_SHIFT;
1590         unsigned long start_index = index;
1591         unsigned long end_index = delalloc_end >> PAGE_SHIFT;
1592         unsigned long pages_locked = 0;
1593         struct page *pages[16];
1594         unsigned long nrpages;
1595         int ret;
1596         int i;
1597
1598         /* the caller is responsible for locking the start index */
1599         if (index == locked_page->index && index == end_index)
1600                 return 0;
1601
1602         /* skip the page at the start index */
1603         nrpages = end_index - index + 1;
1604         while (nrpages > 0) {
1605                 ret = find_get_pages_contig(inode->i_mapping, index,
1606                                      min_t(unsigned long,
1607                                      nrpages, ARRAY_SIZE(pages)), pages);
1608                 if (ret == 0) {
1609                         ret = -EAGAIN;
1610                         goto done;
1611                 }
1612                 /* now we have an array of pages, lock them all */
1613                 for (i = 0; i < ret; i++) {
1614                         /*
1615                          * the caller is taking responsibility for
1616                          * locked_page
1617                          */
1618                         if (pages[i] != locked_page) {
1619                                 lock_page(pages[i]);
1620                                 if (!PageDirty(pages[i]) ||
1621                                     pages[i]->mapping != inode->i_mapping) {
1622                                         ret = -EAGAIN;
1623                                         unlock_page(pages[i]);
1624                                         put_page(pages[i]);
1625                                         goto done;
1626                                 }
1627                         }
1628                         put_page(pages[i]);
1629                         pages_locked++;
1630                 }
1631                 nrpages -= ret;
1632                 index += ret;
1633                 cond_resched();
1634         }
1635         ret = 0;
1636 done:
1637         if (ret && pages_locked) {
1638                 __unlock_for_delalloc(inode, locked_page,
1639                               delalloc_start,
1640                               ((u64)(start_index + pages_locked - 1)) <<
1641                               PAGE_SHIFT);
1642         }
1643         return ret;
1644 }
1645
1646 /*
1647  * find a contiguous range of bytes in the file marked as delalloc, not
1648  * more than 'max_bytes'.  start and end are used to return the range,
1649  *
1650  * 1 is returned if we find something, 0 if nothing was in the tree
1651  */
1652 STATIC u64 find_lock_delalloc_range(struct inode *inode,
1653                                     struct extent_io_tree *tree,
1654                                     struct page *locked_page, u64 *start,
1655                                     u64 *end, u64 max_bytes)
1656 {
1657         u64 delalloc_start;
1658         u64 delalloc_end;
1659         u64 found;
1660         struct extent_state *cached_state = NULL;
1661         int ret;
1662         int loops = 0;
1663
1664 again:
1665         /* step one, find a bunch of delalloc bytes starting at start */
1666         delalloc_start = *start;
1667         delalloc_end = 0;
1668         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1669                                     max_bytes, &cached_state);
1670         if (!found || delalloc_end <= *start) {
1671                 *start = delalloc_start;
1672                 *end = delalloc_end;
1673                 free_extent_state(cached_state);
1674                 return 0;
1675         }
1676
1677         /*
1678          * start comes from the offset of locked_page.  We have to lock
1679          * pages in order, so we can't process delalloc bytes before
1680          * locked_page
1681          */
1682         if (delalloc_start < *start)
1683                 delalloc_start = *start;
1684
1685         /*
1686          * make sure to limit the number of pages we try to lock down
1687          */
1688         if (delalloc_end + 1 - delalloc_start > max_bytes)
1689                 delalloc_end = delalloc_start + max_bytes - 1;
1690
1691         /* step two, lock all the pages after the page that has start */
1692         ret = lock_delalloc_pages(inode, locked_page,
1693                                   delalloc_start, delalloc_end);
1694         if (ret == -EAGAIN) {
1695                 /* some of the pages are gone, lets avoid looping by
1696                  * shortening the size of the delalloc range we're searching
1697                  */
1698                 free_extent_state(cached_state);
1699                 cached_state = NULL;
1700                 if (!loops) {
1701                         max_bytes = PAGE_SIZE;
1702                         loops = 1;
1703                         goto again;
1704                 } else {
1705                         found = 0;
1706                         goto out_failed;
1707                 }
1708         }
1709         BUG_ON(ret); /* Only valid values are 0 and -EAGAIN */
1710
1711         /* step three, lock the state bits for the whole range */
1712         lock_extent_bits(tree, delalloc_start, delalloc_end, &cached_state);
1713
1714         /* then test to make sure it is all still delalloc */
1715         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1716                              EXTENT_DELALLOC, 1, cached_state);
1717         if (!ret) {
1718                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1719                                      &cached_state, GFP_NOFS);
1720                 __unlock_for_delalloc(inode, locked_page,
1721                               delalloc_start, delalloc_end);
1722                 cond_resched();
1723                 goto again;
1724         }
1725         free_extent_state(cached_state);
1726         *start = delalloc_start;
1727         *end = delalloc_end;
1728 out_failed:
1729         return found;
1730 }
1731
1732 void extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
1733                                  u64 delalloc_end, struct page *locked_page,
1734                                  unsigned clear_bits,
1735                                  unsigned long page_ops)
1736 {
1737         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
1738         int ret;
1739         struct page *pages[16];
1740         unsigned long index = start >> PAGE_SHIFT;
1741         unsigned long end_index = end >> PAGE_SHIFT;
1742         unsigned long nr_pages = end_index - index + 1;
1743         int i;
1744
1745         clear_extent_bit(tree, start, end, clear_bits, 1, 0, NULL, GFP_NOFS);
1746         if (page_ops == 0)
1747                 return;
1748
1749         if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
1750                 mapping_set_error(inode->i_mapping, -EIO);
1751
1752         while (nr_pages > 0) {
1753                 ret = find_get_pages_contig(inode->i_mapping, index,
1754                                      min_t(unsigned long,
1755                                      nr_pages, ARRAY_SIZE(pages)), pages);
1756                 for (i = 0; i < ret; i++) {
1757
1758                         if (page_ops & PAGE_SET_PRIVATE2)
1759                                 SetPagePrivate2(pages[i]);
1760
1761                         if (pages[i] == locked_page) {
1762                                 put_page(pages[i]);
1763                                 continue;
1764                         }
1765                         if (page_ops & PAGE_CLEAR_DIRTY)
1766                                 clear_page_dirty_for_io(pages[i]);
1767                         if (page_ops & PAGE_SET_WRITEBACK)
1768                                 set_page_writeback(pages[i]);
1769                         if (page_ops & PAGE_SET_ERROR)
1770                                 SetPageError(pages[i]);
1771                         if (page_ops & PAGE_END_WRITEBACK)
1772                                 end_page_writeback(pages[i]);
1773                         if (page_ops & PAGE_UNLOCK)
1774                                 unlock_page(pages[i]);
1775                         put_page(pages[i]);
1776                 }
1777                 nr_pages -= ret;
1778                 index += ret;
1779                 cond_resched();
1780         }
1781 }
1782
1783 /*
1784  * count the number of bytes in the tree that have a given bit(s)
1785  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1786  * cached.  The total number found is returned.
1787  */
1788 u64 count_range_bits(struct extent_io_tree *tree,
1789                      u64 *start, u64 search_end, u64 max_bytes,
1790                      unsigned bits, int contig)
1791 {
1792         struct rb_node *node;
1793         struct extent_state *state;
1794         u64 cur_start = *start;
1795         u64 total_bytes = 0;
1796         u64 last = 0;
1797         int found = 0;
1798
1799         if (WARN_ON(search_end <= cur_start))
1800                 return 0;
1801
1802         spin_lock(&tree->lock);
1803         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1804                 total_bytes = tree->dirty_bytes;
1805                 goto out;
1806         }
1807         /*
1808          * this search will find all the extents that end after
1809          * our range starts.
1810          */
1811         node = tree_search(tree, cur_start);
1812         if (!node)
1813                 goto out;
1814
1815         while (1) {
1816                 state = rb_entry(node, struct extent_state, rb_node);
1817                 if (state->start > search_end)
1818                         break;
1819                 if (contig && found && state->start > last + 1)
1820                         break;
1821                 if (state->end >= cur_start && (state->state & bits) == bits) {
1822                         total_bytes += min(search_end, state->end) + 1 -
1823                                        max(cur_start, state->start);
1824                         if (total_bytes >= max_bytes)
1825                                 break;
1826                         if (!found) {
1827                                 *start = max(cur_start, state->start);
1828                                 found = 1;
1829                         }
1830                         last = state->end;
1831                 } else if (contig && found) {
1832                         break;
1833                 }
1834                 node = rb_next(node);
1835                 if (!node)
1836                         break;
1837         }
1838 out:
1839         spin_unlock(&tree->lock);
1840         return total_bytes;
1841 }
1842
1843 /*
1844  * set the private field for a given byte offset in the tree.  If there isn't
1845  * an extent_state there already, this does nothing.
1846  */
1847 static noinline int set_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         state->failrec = failrec;
1870 out:
1871         spin_unlock(&tree->lock);
1872         return ret;
1873 }
1874
1875 static noinline int get_state_failrec(struct extent_io_tree *tree, u64 start,
1876                 struct io_failure_record **failrec)
1877 {
1878         struct rb_node *node;
1879         struct extent_state *state;
1880         int ret = 0;
1881
1882         spin_lock(&tree->lock);
1883         /*
1884          * this search will find all the extents that end after
1885          * our range starts.
1886          */
1887         node = tree_search(tree, start);
1888         if (!node) {
1889                 ret = -ENOENT;
1890                 goto out;
1891         }
1892         state = rb_entry(node, struct extent_state, rb_node);
1893         if (state->start != start) {
1894                 ret = -ENOENT;
1895                 goto out;
1896         }
1897         *failrec = state->failrec;
1898 out:
1899         spin_unlock(&tree->lock);
1900         return ret;
1901 }
1902
1903 /*
1904  * searches a range in the state tree for a given mask.
1905  * If 'filled' == 1, this returns 1 only if every extent in the tree
1906  * has the bits set.  Otherwise, 1 is returned if any bit in the
1907  * range is found set.
1908  */
1909 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1910                    unsigned bits, int filled, struct extent_state *cached)
1911 {
1912         struct extent_state *state = NULL;
1913         struct rb_node *node;
1914         int bitset = 0;
1915
1916         spin_lock(&tree->lock);
1917         if (cached && extent_state_in_tree(cached) && cached->start <= start &&
1918             cached->end > start)
1919                 node = &cached->rb_node;
1920         else
1921                 node = tree_search(tree, start);
1922         while (node && start <= end) {
1923                 state = rb_entry(node, struct extent_state, rb_node);
1924
1925                 if (filled && state->start > start) {
1926                         bitset = 0;
1927                         break;
1928                 }
1929
1930                 if (state->start > end)
1931                         break;
1932
1933                 if (state->state & bits) {
1934                         bitset = 1;
1935                         if (!filled)
1936                                 break;
1937                 } else if (filled) {
1938                         bitset = 0;
1939                         break;
1940                 }
1941
1942                 if (state->end == (u64)-1)
1943                         break;
1944
1945                 start = state->end + 1;
1946                 if (start > end)
1947                         break;
1948                 node = rb_next(node);
1949                 if (!node) {
1950                         if (filled)
1951                                 bitset = 0;
1952                         break;
1953                 }
1954         }
1955         spin_unlock(&tree->lock);
1956         return bitset;
1957 }
1958
1959 /*
1960  * helper function to set a given page up to date if all the
1961  * extents in the tree for that page are up to date
1962  */
1963 static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
1964 {
1965         u64 start = page_offset(page);
1966         u64 end = start + PAGE_SIZE - 1;
1967         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
1968                 SetPageUptodate(page);
1969 }
1970
1971 int free_io_failure(struct inode *inode, struct io_failure_record *rec)
1972 {
1973         int ret;
1974         int err = 0;
1975         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
1976
1977         set_state_failrec(failure_tree, rec->start, NULL);
1978         ret = clear_extent_bits(failure_tree, rec->start,
1979                                 rec->start + rec->len - 1,
1980                                 EXTENT_LOCKED | EXTENT_DIRTY);
1981         if (ret)
1982                 err = ret;
1983
1984         ret = clear_extent_bits(&BTRFS_I(inode)->io_tree, rec->start,
1985                                 rec->start + rec->len - 1,
1986                                 EXTENT_DAMAGED);
1987         if (ret && !err)
1988                 err = ret;
1989
1990         kfree(rec);
1991         return err;
1992 }
1993
1994 /*
1995  * this bypasses the standard btrfs submit functions deliberately, as
1996  * the standard behavior is to write all copies in a raid setup. here we only
1997  * want to write the one bad copy. so we do the mapping for ourselves and issue
1998  * submit_bio directly.
1999  * to avoid any synchronization issues, wait for the data after writing, which
2000  * actually prevents the read that triggered the error from finishing.
2001  * currently, there can be no more than two copies of every data bit. thus,
2002  * exactly one rewrite is required.
2003  */
2004 int repair_io_failure(struct inode *inode, u64 start, u64 length, u64 logical,
2005                       struct page *page, unsigned int pg_offset, int mirror_num)
2006 {
2007         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2008         struct bio *bio;
2009         struct btrfs_device *dev;
2010         u64 map_length = 0;
2011         u64 sector;
2012         struct btrfs_bio *bbio = NULL;
2013         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
2014         int ret;
2015
2016         ASSERT(!(fs_info->sb->s_flags & MS_RDONLY));
2017         BUG_ON(!mirror_num);
2018
2019         /* we can't repair anything in raid56 yet */
2020         if (btrfs_is_parity_mirror(map_tree, logical, length, mirror_num))
2021                 return 0;
2022
2023         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2024         if (!bio)
2025                 return -EIO;
2026         bio->bi_iter.bi_size = 0;
2027         map_length = length;
2028
2029         /*
2030          * Avoid races with device replace and make sure our bbio has devices
2031          * associated to its stripes that don't go away while we are doing the
2032          * read repair operation.
2033          */
2034         btrfs_bio_counter_inc_blocked(fs_info);
2035         ret = btrfs_map_block(fs_info, WRITE, logical,
2036                               &map_length, &bbio, mirror_num);
2037         if (ret) {
2038                 btrfs_bio_counter_dec(fs_info);
2039                 bio_put(bio);
2040                 return -EIO;
2041         }
2042         BUG_ON(mirror_num != bbio->mirror_num);
2043         sector = bbio->stripes[mirror_num-1].physical >> 9;
2044         bio->bi_iter.bi_sector = sector;
2045         dev = bbio->stripes[mirror_num-1].dev;
2046         btrfs_put_bbio(bbio);
2047         if (!dev || !dev->bdev || !dev->writeable) {
2048                 btrfs_bio_counter_dec(fs_info);
2049                 bio_put(bio);
2050                 return -EIO;
2051         }
2052         bio->bi_bdev = dev->bdev;
2053         bio_set_op_attrs(bio, REQ_OP_WRITE, WRITE_SYNC);
2054         bio_add_page(bio, page, length, pg_offset);
2055
2056         if (btrfsic_submit_bio_wait(bio)) {
2057                 /* try to remap that extent elsewhere? */
2058                 btrfs_bio_counter_dec(fs_info);
2059                 bio_put(bio);
2060                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
2061                 return -EIO;
2062         }
2063
2064         btrfs_info_rl_in_rcu(fs_info,
2065                 "read error corrected: ino %llu off %llu (dev %s sector %llu)",
2066                                   btrfs_ino(inode), start,
2067                                   rcu_str_deref(dev->name), sector);
2068         btrfs_bio_counter_dec(fs_info);
2069         bio_put(bio);
2070         return 0;
2071 }
2072
2073 int repair_eb_io_failure(struct btrfs_root *root, struct extent_buffer *eb,
2074                          int mirror_num)
2075 {
2076         u64 start = eb->start;
2077         unsigned long i, num_pages = num_extent_pages(eb->start, eb->len);
2078         int ret = 0;
2079
2080         if (root->fs_info->sb->s_flags & MS_RDONLY)
2081                 return -EROFS;
2082
2083         for (i = 0; i < num_pages; i++) {
2084                 struct page *p = eb->pages[i];
2085
2086                 ret = repair_io_failure(root->fs_info->btree_inode, start,
2087                                         PAGE_SIZE, start, p,
2088                                         start - page_offset(p), mirror_num);
2089                 if (ret)
2090                         break;
2091                 start += PAGE_SIZE;
2092         }
2093
2094         return ret;
2095 }
2096
2097 /*
2098  * each time an IO finishes, we do a fast check in the IO failure tree
2099  * to see if we need to process or clean up an io_failure_record
2100  */
2101 int clean_io_failure(struct inode *inode, u64 start, struct page *page,
2102                      unsigned int pg_offset)
2103 {
2104         u64 private;
2105         struct io_failure_record *failrec;
2106         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2107         struct extent_state *state;
2108         int num_copies;
2109         int ret;
2110
2111         private = 0;
2112         ret = count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
2113                                 (u64)-1, 1, EXTENT_DIRTY, 0);
2114         if (!ret)
2115                 return 0;
2116
2117         ret = get_state_failrec(&BTRFS_I(inode)->io_failure_tree, start,
2118                         &failrec);
2119         if (ret)
2120                 return 0;
2121
2122         BUG_ON(!failrec->this_mirror);
2123
2124         if (failrec->in_validation) {
2125                 /* there was no real error, just free the record */
2126                 pr_debug("clean_io_failure: freeing dummy error at %llu\n",
2127                          failrec->start);
2128                 goto out;
2129         }
2130         if (fs_info->sb->s_flags & MS_RDONLY)
2131                 goto out;
2132
2133         spin_lock(&BTRFS_I(inode)->io_tree.lock);
2134         state = find_first_extent_bit_state(&BTRFS_I(inode)->io_tree,
2135                                             failrec->start,
2136                                             EXTENT_LOCKED);
2137         spin_unlock(&BTRFS_I(inode)->io_tree.lock);
2138
2139         if (state && state->start <= failrec->start &&
2140             state->end >= failrec->start + failrec->len - 1) {
2141                 num_copies = btrfs_num_copies(fs_info, failrec->logical,
2142                                               failrec->len);
2143                 if (num_copies > 1)  {
2144                         repair_io_failure(inode, start, failrec->len,
2145                                           failrec->logical, page,
2146                                           pg_offset, failrec->failed_mirror);
2147                 }
2148         }
2149
2150 out:
2151         free_io_failure(inode, failrec);
2152
2153         return 0;
2154 }
2155
2156 /*
2157  * Can be called when
2158  * - hold extent lock
2159  * - under ordered extent
2160  * - the inode is freeing
2161  */
2162 void btrfs_free_io_failure_record(struct inode *inode, u64 start, u64 end)
2163 {
2164         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2165         struct io_failure_record *failrec;
2166         struct extent_state *state, *next;
2167
2168         if (RB_EMPTY_ROOT(&failure_tree->state))
2169                 return;
2170
2171         spin_lock(&failure_tree->lock);
2172         state = find_first_extent_bit_state(failure_tree, start, EXTENT_DIRTY);
2173         while (state) {
2174                 if (state->start > end)
2175                         break;
2176
2177                 ASSERT(state->end <= end);
2178
2179                 next = next_state(state);
2180
2181                 failrec = state->failrec;
2182                 free_extent_state(state);
2183                 kfree(failrec);
2184
2185                 state = next;
2186         }
2187         spin_unlock(&failure_tree->lock);
2188 }
2189
2190 int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
2191                 struct io_failure_record **failrec_ret)
2192 {
2193         struct io_failure_record *failrec;
2194         struct extent_map *em;
2195         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2196         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2197         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2198         int ret;
2199         u64 logical;
2200
2201         ret = get_state_failrec(failure_tree, start, &failrec);
2202         if (ret) {
2203                 failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
2204                 if (!failrec)
2205                         return -ENOMEM;
2206
2207                 failrec->start = start;
2208                 failrec->len = end - start + 1;
2209                 failrec->this_mirror = 0;
2210                 failrec->bio_flags = 0;
2211                 failrec->in_validation = 0;
2212
2213                 read_lock(&em_tree->lock);
2214                 em = lookup_extent_mapping(em_tree, start, failrec->len);
2215                 if (!em) {
2216                         read_unlock(&em_tree->lock);
2217                         kfree(failrec);
2218                         return -EIO;
2219                 }
2220
2221                 if (em->start > start || em->start + em->len <= start) {
2222                         free_extent_map(em);
2223                         em = NULL;
2224                 }
2225                 read_unlock(&em_tree->lock);
2226                 if (!em) {
2227                         kfree(failrec);
2228                         return -EIO;
2229                 }
2230
2231                 logical = start - em->start;
2232                 logical = em->block_start + logical;
2233                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2234                         logical = em->block_start;
2235                         failrec->bio_flags = EXTENT_BIO_COMPRESSED;
2236                         extent_set_compress_type(&failrec->bio_flags,
2237                                                  em->compress_type);
2238                 }
2239
2240                 pr_debug("Get IO Failure Record: (new) logical=%llu, start=%llu, len=%llu\n",
2241                          logical, start, failrec->len);
2242
2243                 failrec->logical = logical;
2244                 free_extent_map(em);
2245
2246                 /* set the bits in the private failure tree */
2247                 ret = set_extent_bits(failure_tree, start, end,
2248                                         EXTENT_LOCKED | EXTENT_DIRTY);
2249                 if (ret >= 0)
2250                         ret = set_state_failrec(failure_tree, start, failrec);
2251                 /* set the bits in the inode's tree */
2252                 if (ret >= 0)
2253                         ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED);
2254                 if (ret < 0) {
2255                         kfree(failrec);
2256                         return ret;
2257                 }
2258         } else {
2259                 pr_debug("Get IO Failure Record: (found) logical=%llu, start=%llu, len=%llu, validation=%d\n",
2260                          failrec->logical, failrec->start, failrec->len,
2261                          failrec->in_validation);
2262                 /*
2263                  * when data can be on disk more than twice, add to failrec here
2264                  * (e.g. with a list for failed_mirror) to make
2265                  * clean_io_failure() clean all those errors at once.
2266                  */
2267         }
2268
2269         *failrec_ret = failrec;
2270
2271         return 0;
2272 }
2273
2274 int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
2275                            struct io_failure_record *failrec, int failed_mirror)
2276 {
2277         int num_copies;
2278
2279         num_copies = btrfs_num_copies(BTRFS_I(inode)->root->fs_info,
2280                                       failrec->logical, failrec->len);
2281         if (num_copies == 1) {
2282                 /*
2283                  * we only have a single copy of the data, so don't bother with
2284                  * all the retry and error correction code that follows. no
2285                  * matter what the error is, it is very likely to persist.
2286                  */
2287                 pr_debug("Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d\n",
2288                          num_copies, failrec->this_mirror, failed_mirror);
2289                 return 0;
2290         }
2291
2292         /*
2293          * there are two premises:
2294          *      a) deliver good data to the caller
2295          *      b) correct the bad sectors on disk
2296          */
2297         if (failed_bio->bi_vcnt > 1) {
2298                 /*
2299                  * to fulfill b), we need to know the exact failing sectors, as
2300                  * we don't want to rewrite any more than the failed ones. thus,
2301                  * we need separate read requests for the failed bio
2302                  *
2303                  * if the following BUG_ON triggers, our validation request got
2304                  * merged. we need separate requests for our algorithm to work.
2305                  */
2306                 BUG_ON(failrec->in_validation);
2307                 failrec->in_validation = 1;
2308                 failrec->this_mirror = failed_mirror;
2309         } else {
2310                 /*
2311                  * we're ready to fulfill a) and b) alongside. get a good copy
2312                  * of the failed sector and if we succeed, we have setup
2313                  * everything for repair_io_failure to do the rest for us.
2314                  */
2315                 if (failrec->in_validation) {
2316                         BUG_ON(failrec->this_mirror != failed_mirror);
2317                         failrec->in_validation = 0;
2318                         failrec->this_mirror = 0;
2319                 }
2320                 failrec->failed_mirror = failed_mirror;
2321                 failrec->this_mirror++;
2322                 if (failrec->this_mirror == failed_mirror)
2323                         failrec->this_mirror++;
2324         }
2325
2326         if (failrec->this_mirror > num_copies) {
2327                 pr_debug("Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d\n",
2328                          num_copies, failrec->this_mirror, failed_mirror);
2329                 return 0;
2330         }
2331
2332         return 1;
2333 }
2334
2335
2336 struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
2337                                     struct io_failure_record *failrec,
2338                                     struct page *page, int pg_offset, int icsum,
2339                                     bio_end_io_t *endio_func, void *data)
2340 {
2341         struct bio *bio;
2342         struct btrfs_io_bio *btrfs_failed_bio;
2343         struct btrfs_io_bio *btrfs_bio;
2344
2345         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2346         if (!bio)
2347                 return NULL;
2348
2349         bio->bi_end_io = endio_func;
2350         bio->bi_iter.bi_sector = failrec->logical >> 9;
2351         bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
2352         bio->bi_iter.bi_size = 0;
2353         bio->bi_private = data;
2354
2355         btrfs_failed_bio = btrfs_io_bio(failed_bio);
2356         if (btrfs_failed_bio->csum) {
2357                 struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2358                 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
2359
2360                 btrfs_bio = btrfs_io_bio(bio);
2361                 btrfs_bio->csum = btrfs_bio->csum_inline;
2362                 icsum *= csum_size;
2363                 memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + icsum,
2364                        csum_size);
2365         }
2366
2367         bio_add_page(bio, page, failrec->len, pg_offset);
2368
2369         return bio;
2370 }
2371
2372 /*
2373  * this is a generic handler for readpage errors (default
2374  * readpage_io_failed_hook). if other copies exist, read those and write back
2375  * good data to the failed position. does not investigate in remapping the
2376  * failed extent elsewhere, hoping the device will be smart enough to do this as
2377  * needed
2378  */
2379
2380 static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
2381                               struct page *page, u64 start, u64 end,
2382                               int failed_mirror)
2383 {
2384         struct io_failure_record *failrec;
2385         struct inode *inode = page->mapping->host;
2386         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2387         struct bio *bio;
2388         int read_mode;
2389         int ret;
2390
2391         BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);
2392
2393         ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
2394         if (ret)
2395                 return ret;
2396
2397         ret = btrfs_check_repairable(inode, failed_bio, failrec, failed_mirror);
2398         if (!ret) {
2399                 free_io_failure(inode, failrec);
2400                 return -EIO;
2401         }
2402
2403         if (failed_bio->bi_vcnt > 1)
2404                 read_mode = READ_SYNC | REQ_FAILFAST_DEV;
2405         else
2406                 read_mode = READ_SYNC;
2407
2408         phy_offset >>= inode->i_sb->s_blocksize_bits;
2409         bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
2410                                       start - page_offset(page),
2411                                       (int)phy_offset, failed_bio->bi_end_io,
2412                                       NULL);
2413         if (!bio) {
2414                 free_io_failure(inode, failrec);
2415                 return -EIO;
2416         }
2417         bio_set_op_attrs(bio, REQ_OP_READ, read_mode);
2418
2419         pr_debug("Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d\n",
2420                  read_mode, failrec->this_mirror, failrec->in_validation);
2421
2422         ret = tree->ops->submit_bio_hook(inode, bio, failrec->this_mirror,
2423                                          failrec->bio_flags, 0);
2424         if (ret) {
2425                 free_io_failure(inode, failrec);
2426                 bio_put(bio);
2427         }
2428
2429         return ret;
2430 }
2431
2432 /* lots and lots of room for performance fixes in the end_bio funcs */
2433
2434 void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
2435 {
2436         int uptodate = (err == 0);
2437         struct extent_io_tree *tree;
2438         int ret = 0;
2439
2440         tree = &BTRFS_I(page->mapping->host)->io_tree;
2441
2442         if (tree->ops && tree->ops->writepage_end_io_hook) {
2443                 ret = tree->ops->writepage_end_io_hook(page, start,
2444                                                end, NULL, uptodate);
2445                 if (ret)
2446                         uptodate = 0;
2447         }
2448
2449         if (!uptodate) {
2450                 ClearPageUptodate(page);
2451                 SetPageError(page);
2452                 ret = ret < 0 ? ret : -EIO;
2453                 mapping_set_error(page->mapping, ret);
2454         }
2455 }
2456
2457 /*
2458  * after a writepage IO is done, we need to:
2459  * clear the uptodate bits on error
2460  * clear the writeback bits in the extent tree for this IO
2461  * end_page_writeback if the page has no more pending IO
2462  *
2463  * Scheduling is not allowed, so the extent state tree is expected
2464  * to have one and only one object corresponding to this IO.
2465  */
2466 static void end_bio_extent_writepage(struct bio *bio)
2467 {
2468         struct bio_vec *bvec;
2469         u64 start;
2470         u64 end;
2471         int i;
2472
2473         bio_for_each_segment_all(bvec, bio, i) {
2474                 struct page *page = bvec->bv_page;
2475
2476                 /* We always issue full-page reads, but if some block
2477                  * in a page fails to read, blk_update_request() will
2478                  * advance bv_offset and adjust bv_len to compensate.
2479                  * Print a warning for nonzero offsets, and an error
2480                  * if they don't add up to a full page.  */
2481                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2482                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2483                                 btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2484                                    "partial page write in btrfs with offset %u and length %u",
2485                                         bvec->bv_offset, bvec->bv_len);
2486                         else
2487                                 btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2488                                    "incomplete page write in btrfs with offset %u and "
2489                                    "length %u",
2490                                         bvec->bv_offset, bvec->bv_len);
2491                 }
2492
2493                 start = page_offset(page);
2494                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2495
2496                 end_extent_writepage(page, bio->bi_error, start, end);
2497                 end_page_writeback(page);
2498         }
2499
2500         bio_put(bio);
2501 }
2502
2503 static void
2504 endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
2505                               int uptodate)
2506 {
2507         struct extent_state *cached = NULL;
2508         u64 end = start + len - 1;
2509
2510         if (uptodate && tree->track_uptodate)
2511                 set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
2512         unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
2513 }
2514
2515 /*
2516  * after a readpage IO is done, we need to:
2517  * clear the uptodate bits on error
2518  * set the uptodate bits if things worked
2519  * set the page up to date if all extents in the tree are uptodate
2520  * clear the lock bit in the extent tree
2521  * unlock the page if there are no other extents locked for it
2522  *
2523  * Scheduling is not allowed, so the extent state tree is expected
2524  * to have one and only one object corresponding to this IO.
2525  */
2526 static void end_bio_extent_readpage(struct bio *bio)
2527 {
2528         struct bio_vec *bvec;
2529         int uptodate = !bio->bi_error;
2530         struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
2531         struct extent_io_tree *tree;
2532         u64 offset = 0;
2533         u64 start;
2534         u64 end;
2535         u64 len;
2536         u64 extent_start = 0;
2537         u64 extent_len = 0;
2538         int mirror;
2539         int ret;
2540         int i;
2541
2542         bio_for_each_segment_all(bvec, bio, i) {
2543                 struct page *page = bvec->bv_page;
2544                 struct inode *inode = page->mapping->host;
2545
2546                 pr_debug("end_bio_extent_readpage: bi_sector=%llu, err=%d, "
2547                          "mirror=%u\n", (u64)bio->bi_iter.bi_sector,
2548                          bio->bi_error, io_bio->mirror_num);
2549                 tree = &BTRFS_I(inode)->io_tree;
2550
2551                 /* We always issue full-page reads, but if some block
2552                  * in a page fails to read, blk_update_request() will
2553                  * advance bv_offset and adjust bv_len to compensate.
2554                  * Print a warning for nonzero offsets, and an error
2555                  * if they don't add up to a full page.  */
2556                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2557                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2558                                 btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2559                                    "partial page read in btrfs with offset %u and length %u",
2560                                         bvec->bv_offset, bvec->bv_len);
2561                         else
2562                                 btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2563                                    "incomplete page read in btrfs with offset %u and "
2564                                    "length %u",
2565                                         bvec->bv_offset, bvec->bv_len);
2566                 }
2567
2568                 start = page_offset(page);
2569                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2570                 len = bvec->bv_len;
2571
2572                 mirror = io_bio->mirror_num;
2573                 if (likely(uptodate && tree->ops &&
2574                            tree->ops->readpage_end_io_hook)) {
2575                         ret = tree->ops->readpage_end_io_hook(io_bio, offset,
2576                                                               page, start, end,
2577                                                               mirror);
2578                         if (ret)
2579                                 uptodate = 0;
2580                         else
2581                                 clean_io_failure(inode, start, page, 0);
2582                 }
2583
2584                 if (likely(uptodate))
2585                         goto readpage_ok;
2586
2587                 if (tree->ops && tree->ops->readpage_io_failed_hook) {
2588                         ret = tree->ops->readpage_io_failed_hook(page, mirror);
2589                         if (!ret && !bio->bi_error)
2590                                 uptodate = 1;
2591                 } else {
2592                         /*
2593                          * The generic bio_readpage_error handles errors the
2594                          * following way: If possible, new read requests are
2595                          * created and submitted and will end up in
2596                          * end_bio_extent_readpage as well (if we're lucky, not
2597                          * in the !uptodate case). In that case it returns 0 and
2598                          * we just go on with the next page in our bio. If it
2599                          * can't handle the error it will return -EIO and we
2600                          * remain responsible for that page.
2601                          */
2602                         ret = bio_readpage_error(bio, offset, page, start, end,
2603                                                  mirror);
2604                         if (ret == 0) {
2605                                 uptodate = !bio->bi_error;
2606                                 offset += len;
2607                                 continue;
2608                         }
2609                 }
2610 readpage_ok:
2611                 if (likely(uptodate)) {
2612                         loff_t i_size = i_size_read(inode);
2613                         pgoff_t end_index = i_size >> PAGE_SHIFT;
2614                         unsigned off;
2615
2616                         /* Zero out the end if this page straddles i_size */
2617                         off = i_size & (PAGE_SIZE-1);
2618                         if (page->index == end_index && off)
2619                                 zero_user_segment(page, off, PAGE_SIZE);
2620                         SetPageUptodate(page);
2621                 } else {
2622                         ClearPageUptodate(page);
2623                         SetPageError(page);
2624                 }
2625                 unlock_page(page);
2626                 offset += len;
2627
2628                 if (unlikely(!uptodate)) {
2629                         if (extent_len) {
2630                                 endio_readpage_release_extent(tree,
2631                                                               extent_start,
2632                                                               extent_len, 1);
2633                                 extent_start = 0;
2634                                 extent_len = 0;
2635                         }
2636                         endio_readpage_release_extent(tree, start,
2637                                                       end - start + 1, 0);
2638                 } else if (!extent_len) {
2639                         extent_start = start;
2640                         extent_len = end + 1 - start;
2641                 } else if (extent_start + extent_len == start) {
2642                         extent_len += end + 1 - start;
2643                 } else {
2644                         endio_readpage_release_extent(tree, extent_start,
2645                                                       extent_len, uptodate);
2646                         extent_start = start;
2647                         extent_len = end + 1 - start;
2648                 }
2649         }
2650
2651         if (extent_len)
2652                 endio_readpage_release_extent(tree, extent_start, extent_len,
2653                                               uptodate);
2654         if (io_bio->end_io)
2655                 io_bio->end_io(io_bio, bio->bi_error);
2656         bio_put(bio);
2657 }
2658
2659 /*
2660  * this allocates from the btrfs_bioset.  We're returning a bio right now
2661  * but you can call btrfs_io_bio for the appropriate container_of magic
2662  */
2663 struct bio *
2664 btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
2665                 gfp_t gfp_flags)
2666 {
2667         struct btrfs_io_bio *btrfs_bio;
2668         struct bio *bio;
2669
2670         bio = bio_alloc_bioset(gfp_flags, nr_vecs, btrfs_bioset);
2671
2672         if (bio == NULL && (current->flags & PF_MEMALLOC)) {
2673                 while (!bio && (nr_vecs /= 2)) {
2674                         bio = bio_alloc_bioset(gfp_flags,
2675                                                nr_vecs, btrfs_bioset);
2676                 }
2677         }
2678
2679         if (bio) {
2680                 bio->bi_bdev = bdev;
2681                 bio->bi_iter.bi_sector = first_sector;
2682                 btrfs_bio = btrfs_io_bio(bio);
2683                 btrfs_bio->csum = NULL;
2684                 btrfs_bio->csum_allocated = NULL;
2685                 btrfs_bio->end_io = NULL;
2686         }
2687         return bio;
2688 }
2689
2690 struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
2691 {
2692         struct btrfs_io_bio *btrfs_bio;
2693         struct bio *new;
2694
2695         new = bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
2696         if (new) {
2697                 btrfs_bio = btrfs_io_bio(new);
2698                 btrfs_bio->csum = NULL;
2699                 btrfs_bio->csum_allocated = NULL;
2700                 btrfs_bio->end_io = NULL;
2701         }
2702         return new;
2703 }
2704
2705 /* this also allocates from the btrfs_bioset */
2706 struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
2707 {
2708         struct btrfs_io_bio *btrfs_bio;
2709         struct bio *bio;
2710
2711         bio = bio_alloc_bioset(gfp_mask, nr_iovecs, btrfs_bioset);
2712         if (bio) {
2713                 btrfs_bio = btrfs_io_bio(bio);
2714                 btrfs_bio->csum = NULL;
2715                 btrfs_bio->csum_allocated = NULL;
2716                 btrfs_bio->end_io = NULL;
2717         }
2718         return bio;
2719 }
2720
2721
2722 static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
2723                                        unsigned long bio_flags)
2724 {
2725         int ret = 0;
2726         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
2727         struct page *page = bvec->bv_page;
2728         struct extent_io_tree *tree = bio->bi_private;
2729         u64 start;
2730
2731         start = page_offset(page) + bvec->bv_offset;
2732
2733         bio->bi_private = NULL;
2734         bio_get(bio);
2735
2736         if (tree->ops && tree->ops->submit_bio_hook)
2737                 ret = tree->ops->submit_bio_hook(page->mapping->host, bio,
2738                                            mirror_num, bio_flags, start);
2739         else
2740                 btrfsic_submit_bio(bio);
2741
2742         bio_put(bio);
2743         return ret;
2744 }
2745
2746 static int merge_bio(struct extent_io_tree *tree, struct page *page,
2747                      unsigned long offset, size_t size, struct bio *bio,
2748                      unsigned long bio_flags)
2749 {
2750         int ret = 0;
2751         if (tree->ops && tree->ops->merge_bio_hook)
2752                 ret = tree->ops->merge_bio_hook(page, offset, size, bio,
2753                                                 bio_flags);
2754         return ret;
2755
2756 }
2757
2758 static int submit_extent_page(int op, int op_flags, struct extent_io_tree *tree,
2759                               struct writeback_control *wbc,
2760                               struct page *page, sector_t sector,
2761                               size_t size, unsigned long offset,
2762                               struct block_device *bdev,
2763                               struct bio **bio_ret,
2764                               unsigned long max_pages,
2765                               bio_end_io_t end_io_func,
2766                               int mirror_num,
2767                               unsigned long prev_bio_flags,
2768                               unsigned long bio_flags,
2769                               bool force_bio_submit)
2770 {
2771         int ret = 0;
2772         struct bio *bio;
2773         int contig = 0;
2774         int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
2775         size_t page_size = min_t(size_t, size, PAGE_SIZE);
2776
2777         if (bio_ret && *bio_ret) {
2778                 bio = *bio_ret;
2779                 if (old_compressed)
2780                         contig = bio->bi_iter.bi_sector == sector;
2781                 else
2782                         contig = bio_end_sector(bio) == sector;
2783
2784                 if (prev_bio_flags != bio_flags || !contig ||
2785                     force_bio_submit ||
2786                     merge_bio(tree, page, offset, page_size, bio, bio_flags) ||
2787                     bio_add_page(bio, page, page_size, offset) < page_size) {
2788                         ret = submit_one_bio(bio, mirror_num, prev_bio_flags);
2789                         if (ret < 0) {
2790                                 *bio_ret = NULL;
2791                                 return ret;
2792                         }
2793                         bio = NULL;
2794                 } else {
2795                         if (wbc)
2796                                 wbc_account_io(wbc, page, page_size);
2797                         return 0;
2798                 }
2799         }
2800
2801         bio = btrfs_bio_alloc(bdev, sector, BIO_MAX_PAGES,
2802                         GFP_NOFS | __GFP_HIGH);
2803         if (!bio)
2804                 return -ENOMEM;
2805
2806         bio_add_page(bio, page, page_size, offset);
2807         bio->bi_end_io = end_io_func;
2808         bio->bi_private = tree;
2809         bio_set_op_attrs(bio, op, op_flags);
2810         if (wbc) {
2811                 wbc_init_bio(wbc, bio);
2812                 wbc_account_io(wbc, page, page_size);
2813         }
2814
2815         if (bio_ret)
2816                 *bio_ret = bio;
2817         else
2818                 ret = submit_one_bio(bio, mirror_num, bio_flags);
2819
2820         return ret;
2821 }
2822
2823 static void attach_extent_buffer_page(struct extent_buffer *eb,
2824                                       struct page *page)
2825 {
2826         if (!PagePrivate(page)) {
2827                 SetPagePrivate(page);
2828                 get_page(page);
2829                 set_page_private(page, (unsigned long)eb);
2830         } else {
2831                 WARN_ON(page->private != (unsigned long)eb);
2832         }
2833 }
2834
2835 void set_page_extent_mapped(struct page *page)
2836 {
2837         if (!PagePrivate(page)) {
2838                 SetPagePrivate(page);
2839                 get_page(page);
2840                 set_page_private(page, EXTENT_PAGE_PRIVATE);
2841         }
2842 }
2843
2844 static struct extent_map *
2845 __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
2846                  u64 start, u64 len, get_extent_t *get_extent,
2847                  struct extent_map **em_cached)
2848 {
2849         struct extent_map *em;
2850
2851         if (em_cached && *em_cached) {
2852                 em = *em_cached;
2853                 if (extent_map_in_tree(em) && start >= em->start &&
2854                     start < extent_map_end(em)) {
2855                         atomic_inc(&em->refs);
2856                         return em;
2857                 }
2858
2859                 free_extent_map(em);
2860                 *em_cached = NULL;
2861         }
2862
2863         em = get_extent(inode, page, pg_offset, start, len, 0);
2864         if (em_cached && !IS_ERR_OR_NULL(em)) {
2865                 BUG_ON(*em_cached);
2866                 atomic_inc(&em->refs);
2867                 *em_cached = em;
2868         }
2869         return em;
2870 }
2871 /*
2872  * basic readpage implementation.  Locked extent state structs are inserted
2873  * into the tree that are removed when the IO is done (by the end_io
2874  * handlers)
2875  * XXX JDM: This needs looking at to ensure proper page locking
2876  * return 0 on success, otherwise return error
2877  */
2878 static int __do_readpage(struct extent_io_tree *tree,
2879                          struct page *page,
2880                          get_extent_t *get_extent,
2881                          struct extent_map **em_cached,
2882                          struct bio **bio, int mirror_num,
2883                          unsigned long *bio_flags, int read_flags,
2884                          u64 *prev_em_start)
2885 {
2886         struct inode *inode = page->mapping->host;
2887         u64 start = page_offset(page);
2888         u64 page_end = start + PAGE_SIZE - 1;
2889         u64 end;
2890         u64 cur = start;
2891         u64 extent_offset;
2892         u64 last_byte = i_size_read(inode);
2893         u64 block_start;
2894         u64 cur_end;
2895         sector_t sector;
2896         struct extent_map *em;
2897         struct block_device *bdev;
2898         int ret = 0;
2899         int nr = 0;
2900         size_t pg_offset = 0;
2901         size_t iosize;
2902         size_t disk_io_size;
2903         size_t blocksize = inode->i_sb->s_blocksize;
2904         unsigned long this_bio_flag = 0;
2905
2906         set_page_extent_mapped(page);
2907
2908         end = page_end;
2909         if (!PageUptodate(page)) {
2910                 if (cleancache_get_page(page) == 0) {
2911                         BUG_ON(blocksize != PAGE_SIZE);
2912                         unlock_extent(tree, start, end);
2913                         goto out;
2914                 }
2915         }
2916
2917         if (page->index == last_byte >> PAGE_SHIFT) {
2918                 char *userpage;
2919                 size_t zero_offset = last_byte & (PAGE_SIZE - 1);
2920
2921                 if (zero_offset) {
2922                         iosize = PAGE_SIZE - zero_offset;
2923                         userpage = kmap_atomic(page);
2924                         memset(userpage + zero_offset, 0, iosize);
2925                         flush_dcache_page(page);
2926                         kunmap_atomic(userpage);
2927                 }
2928         }
2929         while (cur <= end) {
2930                 unsigned long pnr = (last_byte >> PAGE_SHIFT) + 1;
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                 pnr -= page->index;
3066                 ret = submit_extent_page(REQ_OP_READ, read_flags, tree, NULL,
3067                                          page, sector, disk_io_size, pg_offset,
3068                                          bdev, bio, pnr,
3069                                          end_bio_extent_readpage, mirror_num,
3070                                          *bio_flags,
3071                                          this_bio_flag,
3072                                          force_bio_submit);
3073                 if (!ret) {
3074                         nr++;
3075                         *bio_flags = this_bio_flag;
3076                 } else {
3077                         SetPageError(page);
3078                         unlock_extent(tree, cur, cur + iosize - 1);
3079                         goto out;
3080                 }
3081                 cur = cur + iosize;
3082                 pg_offset += iosize;
3083         }
3084 out:
3085         if (!nr) {
3086                 if (!PageError(page))
3087                         SetPageUptodate(page);
3088                 unlock_page(page);
3089         }
3090         return ret;
3091 }
3092
3093 static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
3094                                              struct page *pages[], int nr_pages,
3095                                              u64 start, u64 end,
3096                                              get_extent_t *get_extent,
3097                                              struct extent_map **em_cached,
3098                                              struct bio **bio, int mirror_num,
3099                                              unsigned long *bio_flags,
3100                                              u64 *prev_em_start)
3101 {
3102         struct inode *inode;
3103         struct btrfs_ordered_extent *ordered;
3104         int index;
3105
3106         inode = pages[0]->mapping->host;
3107         while (1) {
3108                 lock_extent(tree, start, end);
3109                 ordered = btrfs_lookup_ordered_range(inode, start,
3110                                                      end - start + 1);
3111                 if (!ordered)
3112                         break;
3113                 unlock_extent(tree, start, end);
3114                 btrfs_start_ordered_extent(inode, ordered, 1);
3115                 btrfs_put_ordered_extent(ordered);
3116         }
3117
3118         for (index = 0; index < nr_pages; index++) {
3119                 __do_readpage(tree, pages[index], get_extent, em_cached, bio,
3120                               mirror_num, bio_flags, 0, prev_em_start);
3121                 put_page(pages[index]);
3122         }
3123 }
3124
3125 static void __extent_readpages(struct extent_io_tree *tree,
3126                                struct page *pages[],
3127                                int nr_pages, get_extent_t *get_extent,
3128                                struct extent_map **em_cached,
3129                                struct bio **bio, int mirror_num,
3130                                unsigned long *bio_flags,
3131                                u64 *prev_em_start)
3132 {
3133         u64 start = 0;
3134         u64 end = 0;
3135         u64 page_start;
3136         int index;
3137         int first_index = 0;
3138
3139         for (index = 0; index < nr_pages; index++) {
3140                 page_start = page_offset(pages[index]);
3141                 if (!end) {
3142                         start = page_start;
3143                         end = start + PAGE_SIZE - 1;
3144                         first_index = index;
3145                 } else if (end + 1 == page_start) {
3146                         end += PAGE_SIZE;
3147                 } else {
3148                         __do_contiguous_readpages(tree, &pages[first_index],
3149                                                   index - first_index, start,
3150                                                   end, get_extent, em_cached,
3151                                                   bio, mirror_num, bio_flags,
3152                                                   prev_em_start);
3153                         start = page_start;
3154                         end = start + PAGE_SIZE - 1;
3155                         first_index = index;
3156                 }
3157         }
3158
3159         if (end)
3160                 __do_contiguous_readpages(tree, &pages[first_index],
3161                                           index - first_index, start,
3162                                           end, get_extent, em_cached, bio,
3163                                           mirror_num, bio_flags,
3164                                           prev_em_start);
3165 }
3166
3167 static int __extent_read_full_page(struct extent_io_tree *tree,
3168                                    struct page *page,
3169                                    get_extent_t *get_extent,
3170                                    struct bio **bio, int mirror_num,
3171                                    unsigned long *bio_flags, 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(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 page *page, 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                                  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_state *cached_state = NULL;
3330         struct extent_map *em;
3331         struct block_device *bdev;
3332         size_t pg_offset = 0;
3333         size_t blocksize;
3334         int ret = 0;
3335         int nr = 0;
3336         bool compressed;
3337
3338         if (tree->ops && tree->ops->writepage_start_hook) {
3339                 ret = tree->ops->writepage_start_hook(page, start,
3340                                                       page_end);
3341                 if (ret) {
3342                         /* Fixup worker will requeue */
3343                         if (ret == -EBUSY)
3344                                 wbc->pages_skipped++;
3345                         else
3346                                 redirty_page_for_writepage(wbc, page);
3347
3348                         update_nr_written(page, wbc, nr_written);
3349                         unlock_page(page);
3350                         ret = 1;
3351                         goto done_unlocked;
3352                 }
3353         }
3354
3355         /*
3356          * we don't want to touch the inode after unlocking the page,
3357          * so we update the mapping writeback index now
3358          */
3359         update_nr_written(page, wbc, nr_written + 1);
3360
3361         end = page_end;
3362         if (i_size <= start) {
3363                 if (tree->ops && tree->ops->writepage_end_io_hook)
3364                         tree->ops->writepage_end_io_hook(page, start,
3365                                                          page_end, NULL, 1);
3366                 goto done;
3367         }
3368
3369         blocksize = inode->i_sb->s_blocksize;
3370
3371         while (cur <= end) {
3372                 u64 em_end;
3373                 unsigned long max_nr;
3374
3375                 if (cur >= i_size) {
3376                         if (tree->ops && tree->ops->writepage_end_io_hook)
3377                                 tree->ops->writepage_end_io_hook(page, cur,
3378                                                          page_end, NULL, 1);
3379                         break;
3380                 }
3381                 em = epd->get_extent(inode, page, pg_offset, cur,
3382                                      end - cur + 1, 1);
3383                 if (IS_ERR_OR_NULL(em)) {
3384                         SetPageError(page);
3385                         ret = PTR_ERR_OR_ZERO(em);
3386                         break;
3387                 }
3388
3389                 extent_offset = cur - em->start;
3390                 em_end = extent_map_end(em);
3391                 BUG_ON(em_end <= cur);
3392                 BUG_ON(end < cur);
3393                 iosize = min(em_end - cur, end - cur + 1);
3394                 iosize = ALIGN(iosize, blocksize);
3395                 sector = (em->block_start + extent_offset) >> 9;
3396                 bdev = em->bdev;
3397                 block_start = em->block_start;
3398                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
3399                 free_extent_map(em);
3400                 em = NULL;
3401
3402                 /*
3403                  * compressed and inline extents are written through other
3404                  * paths in the FS
3405                  */
3406                 if (compressed || block_start == EXTENT_MAP_HOLE ||
3407                     block_start == EXTENT_MAP_INLINE) {
3408                         /*
3409                          * end_io notification does not happen here for
3410                          * compressed extents
3411                          */
3412                         if (!compressed && tree->ops &&
3413                             tree->ops->writepage_end_io_hook)
3414                                 tree->ops->writepage_end_io_hook(page, cur,
3415                                                          cur + iosize - 1,
3416                                                          NULL, 1);
3417                         else if (compressed) {
3418                                 /* we don't want to end_page_writeback on
3419                                  * a compressed extent.  this happens
3420                                  * elsewhere
3421                                  */
3422                                 nr++;
3423                         }
3424
3425                         cur += iosize;
3426                         pg_offset += iosize;
3427                         continue;
3428                 }
3429
3430                 max_nr = (i_size >> PAGE_SHIFT) + 1;
3431
3432                 set_range_writeback(tree, cur, cur + iosize - 1);
3433                 if (!PageWriteback(page)) {
3434                         btrfs_err(BTRFS_I(inode)->root->fs_info,
3435                                    "page %lu not writeback, cur %llu end %llu",
3436                                page->index, cur, end);
3437                 }
3438
3439                 ret = submit_extent_page(REQ_OP_WRITE, write_flags, tree, wbc,
3440                                          page, sector, iosize, pg_offset,
3441                                          bdev, &epd->bio, max_nr,
3442                                          end_bio_extent_writepage,
3443                                          0, 0, 0, false);
3444                 if (ret)
3445                         SetPageError(page);
3446
3447                 cur = cur + iosize;
3448                 pg_offset += iosize;
3449                 nr++;
3450         }
3451 done:
3452         *nr_ret = nr;
3453
3454 done_unlocked:
3455
3456         /* drop our reference on any cached states */
3457         free_extent_state(cached_state);
3458         return ret;
3459 }
3460
3461 /*
3462  * the writepage semantics are similar to regular writepage.  extent
3463  * records are inserted to lock ranges in the tree, and as dirty areas
3464  * are found, they are marked writeback.  Then the lock bits are removed
3465  * and the end_io handler clears the writeback ranges
3466  */
3467 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
3468                               void *data)
3469 {
3470         struct inode *inode = page->mapping->host;
3471         struct extent_page_data *epd = data;
3472         u64 start = page_offset(page);
3473         u64 page_end = start + PAGE_SIZE - 1;
3474         int ret;
3475         int nr = 0;
3476         size_t pg_offset = 0;
3477         loff_t i_size = i_size_read(inode);
3478         unsigned long end_index = i_size >> PAGE_SHIFT;
3479         int write_flags = 0;
3480         unsigned long nr_written = 0;
3481
3482         if (wbc->sync_mode == WB_SYNC_ALL)
3483                 write_flags = WRITE_SYNC;
3484
3485         trace___extent_writepage(page, inode, wbc);
3486
3487         WARN_ON(!PageLocked(page));
3488
3489         ClearPageError(page);
3490
3491         pg_offset = i_size & (PAGE_SIZE - 1);
3492         if (page->index > end_index ||
3493            (page->index == end_index && !pg_offset)) {
3494                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
3495                 unlock_page(page);
3496                 return 0;
3497         }
3498
3499         if (page->index == end_index) {
3500                 char *userpage;
3501
3502                 userpage = kmap_atomic(page);
3503                 memset(userpage + pg_offset, 0,
3504                        PAGE_SIZE - pg_offset);
3505                 kunmap_atomic(userpage);
3506                 flush_dcache_page(page);
3507         }
3508
3509         pg_offset = 0;
3510
3511         set_page_extent_mapped(page);
3512
3513         ret = writepage_delalloc(inode, page, wbc, epd, start, &nr_written);
3514         if (ret == 1)
3515                 goto done_unlocked;
3516         if (ret)
3517                 goto done;
3518
3519         ret = __extent_writepage_io(inode, page, wbc, epd,
3520                                     i_size, nr_written, write_flags, &nr);
3521         if (ret == 1)
3522                 goto done_unlocked;
3523
3524 done:
3525         if (nr == 0) {
3526                 /* make sure the mapping tag for page dirty gets cleared */
3527                 set_page_writeback(page);
3528                 end_page_writeback(page);
3529         }
3530         if (PageError(page)) {
3531                 ret = ret < 0 ? ret : -EIO;
3532                 end_extent_writepage(page, ret, start, page_end);
3533         }
3534         unlock_page(page);
3535         return ret;
3536
3537 done_unlocked:
3538         return 0;
3539 }
3540
3541 void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
3542 {
3543         wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
3544                        TASK_UNINTERRUPTIBLE);
3545 }
3546
3547 static noinline_for_stack int
3548 lock_extent_buffer_for_io(struct extent_buffer *eb,
3549                           struct btrfs_fs_info *fs_info,
3550                           struct extent_page_data *epd)
3551 {
3552         unsigned long i, num_pages;
3553         int flush = 0;
3554         int ret = 0;
3555
3556         if (!btrfs_try_tree_write_lock(eb)) {
3557                 flush = 1;
3558                 flush_write_bio(epd);
3559                 btrfs_tree_lock(eb);
3560         }
3561
3562         if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
3563                 btrfs_tree_unlock(eb);
3564                 if (!epd->sync_io)
3565                         return 0;
3566                 if (!flush) {
3567                         flush_write_bio(epd);
3568                         flush = 1;
3569                 }
3570                 while (1) {
3571                         wait_on_extent_buffer_writeback(eb);
3572                         btrfs_tree_lock(eb);
3573                         if (!test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags))
3574                                 break;
3575                         btrfs_tree_unlock(eb);
3576                 }
3577         }
3578
3579         /*
3580          * We need to do this to prevent races in people who check if the eb is
3581          * under IO since we can end up having no IO bits set for a short period
3582          * of time.
3583          */
3584         spin_lock(&eb->refs_lock);
3585         if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3586                 set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3587                 spin_unlock(&eb->refs_lock);
3588                 btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
3589                 __percpu_counter_add(&fs_info->dirty_metadata_bytes,
3590                                      -eb->len,
3591                                      fs_info->dirty_metadata_batch);
3592                 ret = 1;
3593         } else {
3594                 spin_unlock(&eb->refs_lock);
3595         }
3596
3597         btrfs_tree_unlock(eb);
3598
3599         if (!ret)
3600                 return ret;
3601
3602         num_pages = num_extent_pages(eb->start, eb->len);
3603         for (i = 0; i < num_pages; i++) {
3604                 struct page *p = eb->pages[i];
3605
3606                 if (!trylock_page(p)) {
3607                         if (!flush) {
3608                                 flush_write_bio(epd);
3609                                 flush = 1;
3610                         }
3611                         lock_page(p);
3612                 }
3613         }
3614
3615         return ret;
3616 }
3617
3618 static void end_extent_buffer_writeback(struct extent_buffer *eb)
3619 {
3620         clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3621         smp_mb__after_atomic();
3622         wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
3623 }
3624
3625 static void set_btree_ioerr(struct page *page)
3626 {
3627         struct extent_buffer *eb = (struct extent_buffer *)page->private;
3628
3629         SetPageError(page);
3630         if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
3631                 return;
3632
3633         /*
3634          * If writeback for a btree extent that doesn't belong to a log tree
3635          * failed, increment the counter transaction->eb_write_errors.
3636          * We do this because while the transaction is running and before it's
3637          * committing (when we call filemap_fdata[write|wait]_range against
3638          * the btree inode), we might have
3639          * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
3640          * returns an error or an error happens during writeback, when we're
3641          * committing the transaction we wouldn't know about it, since the pages
3642          * can be no longer dirty nor marked anymore for writeback (if a
3643          * subsequent modification to the extent buffer didn't happen before the
3644          * transaction commit), which makes filemap_fdata[write|wait]_range not
3645          * able to find the pages tagged with SetPageError at transaction
3646          * commit time. So if this happens we must abort the transaction,
3647          * otherwise we commit a super block with btree roots that point to
3648          * btree nodes/leafs whose content on disk is invalid - either garbage
3649          * or the content of some node/leaf from a past generation that got
3650          * cowed or deleted and is no longer valid.
3651          *
3652          * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
3653          * not be enough - we need to distinguish between log tree extents vs
3654          * non-log tree extents, and the next filemap_fdatawait_range() call
3655          * will catch and clear such errors in the mapping - and that call might
3656          * be from a log sync and not from a transaction commit. Also, checking
3657          * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
3658          * not done and would not be reliable - the eb might have been released
3659          * from memory and reading it back again means that flag would not be
3660          * set (since it's a runtime flag, not persisted on disk).
3661          *
3662          * Using the flags below in the btree inode also makes us achieve the
3663          * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
3664          * writeback for all dirty pages and before filemap_fdatawait_range()
3665          * is called, the writeback for all dirty pages had already finished
3666          * with errors - because we were not using AS_EIO/AS_ENOSPC,
3667          * filemap_fdatawait_range() would return success, as it could not know
3668          * that writeback errors happened (the pages were no longer tagged for
3669          * writeback).
3670          */
3671         switch (eb->log_index) {
3672         case -1:
3673                 set_bit(BTRFS_FS_BTREE_ERR, &eb->fs_info->flags);
3674                 break;
3675         case 0:
3676                 set_bit(BTRFS_FS_LOG1_ERR, &eb->fs_info->flags);
3677                 break;
3678         case 1:
3679                 set_bit(BTRFS_FS_LOG2_ERR, &eb->fs_info->flags);
3680                 break;
3681         default:
3682                 BUG(); /* unexpected, logic error */
3683         }
3684 }
3685
3686 static void end_bio_extent_buffer_writepage(struct bio *bio)
3687 {
3688         struct bio_vec *bvec;
3689         struct extent_buffer *eb;
3690         int i, done;
3691
3692         bio_for_each_segment_all(bvec, bio, i) {
3693                 struct page *page = bvec->bv_page;
3694
3695                 eb = (struct extent_buffer *)page->private;
3696                 BUG_ON(!eb);
3697                 done = atomic_dec_and_test(&eb->io_pages);
3698
3699                 if (bio->bi_error ||
3700                     test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
3701                         ClearPageUptodate(page);
3702                         set_btree_ioerr(page);
3703                 }
3704
3705                 end_page_writeback(page);
3706
3707                 if (!done)
3708                         continue;
3709
3710                 end_extent_buffer_writeback(eb);
3711         }
3712
3713         bio_put(bio);
3714 }
3715
3716 static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
3717                         struct btrfs_fs_info *fs_info,
3718                         struct writeback_control *wbc,
3719                         struct extent_page_data *epd)
3720 {
3721         struct block_device *bdev = fs_info->fs_devices->latest_bdev;
3722         struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
3723         u64 offset = eb->start;
3724         unsigned long i, num_pages;
3725         unsigned long bio_flags = 0;
3726         int write_flags = (epd->sync_io ? WRITE_SYNC : 0) | REQ_META;
3727         int ret = 0;
3728
3729         clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
3730         num_pages = num_extent_pages(eb->start, eb->len);
3731         atomic_set(&eb->io_pages, num_pages);
3732         if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
3733                 bio_flags = EXTENT_BIO_TREE_LOG;
3734
3735         for (i = 0; i < num_pages; i++) {
3736                 struct page *p = eb->pages[i];
3737
3738                 clear_page_dirty_for_io(p);
3739                 set_page_writeback(p);
3740                 ret = submit_extent_page(REQ_OP_WRITE, write_flags, tree, wbc,
3741                                          p, offset >> 9, PAGE_SIZE, 0, bdev,
3742                                          &epd->bio, -1,
3743                                          end_bio_extent_buffer_writepage,
3744                                          0, epd->bio_flags, bio_flags, false);
3745                 epd->bio_flags = bio_flags;
3746                 if (ret) {
3747                         set_btree_ioerr(p);
3748                         end_page_writeback(p);
3749                         if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
3750                                 end_extent_buffer_writeback(eb);
3751                         ret = -EIO;
3752                         break;
3753                 }
3754                 offset += PAGE_SIZE;
3755                 update_nr_written(p, wbc, 1);
3756                 unlock_page(p);
3757         }
3758
3759         if (unlikely(ret)) {
3760                 for (; i < num_pages; i++) {
3761                         struct page *p = eb->pages[i];
3762                         clear_page_dirty_for_io(p);
3763                         unlock_page(p);
3764                 }
3765         }
3766
3767         return ret;
3768 }
3769
3770 int btree_write_cache_pages(struct address_space *mapping,
3771                                    struct writeback_control *wbc)
3772 {
3773         struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
3774         struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
3775         struct extent_buffer *eb, *prev_eb = NULL;
3776         struct extent_page_data epd = {
3777                 .bio = NULL,
3778                 .tree = tree,
3779                 .extent_locked = 0,
3780                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
3781                 .bio_flags = 0,
3782         };
3783         int ret = 0;
3784         int done = 0;
3785         int nr_to_write_done = 0;
3786         struct pagevec pvec;
3787         int nr_pages;
3788         pgoff_t index;
3789         pgoff_t end;            /* Inclusive */
3790         int scanned = 0;
3791         int tag;
3792
3793         pagevec_init(&pvec, 0);
3794         if (wbc->range_cyclic) {
3795                 index = mapping->writeback_index; /* Start from prev offset */
3796                 end = -1;
3797         } else {
3798                 index = wbc->range_start >> PAGE_SHIFT;
3799                 end = wbc->range_end >> PAGE_SHIFT;
3800                 scanned = 1;
3801         }
3802         if (wbc->sync_mode == WB_SYNC_ALL)
3803                 tag = PAGECACHE_TAG_TOWRITE;
3804         else
3805                 tag = PAGECACHE_TAG_DIRTY;
3806 retry:
3807         if (wbc->sync_mode == WB_SYNC_ALL)
3808                 tag_pages_for_writeback(mapping, index, end);
3809         while (!done && !nr_to_write_done && (index <= end) &&
3810                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3811                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3812                 unsigned i;
3813
3814                 scanned = 1;
3815                 for (i = 0; i < nr_pages; i++) {
3816                         struct page *page = pvec.pages[i];
3817
3818                         if (!PagePrivate(page))
3819                                 continue;
3820
3821                         if (!wbc->range_cyclic && page->index > end) {
3822                                 done = 1;
3823                                 break;
3824                         }
3825
3826                         spin_lock(&mapping->private_lock);
3827                         if (!PagePrivate(page)) {
3828                                 spin_unlock(&mapping->private_lock);
3829                                 continue;
3830                         }
3831
3832                         eb = (struct extent_buffer *)page->private;
3833
3834                         /*
3835                          * Shouldn't happen and normally this would be a BUG_ON
3836                          * but no sense in crashing the users box for something
3837                          * we can survive anyway.
3838                          */
3839                         if (WARN_ON(!eb)) {
3840                                 spin_unlock(&mapping->private_lock);
3841                                 continue;
3842                         }
3843
3844                         if (eb == prev_eb) {
3845                                 spin_unlock(&mapping->private_lock);
3846                                 continue;
3847                         }
3848
3849                         ret = atomic_inc_not_zero(&eb->refs);
3850                         spin_unlock(&mapping->private_lock);
3851                         if (!ret)
3852                                 continue;
3853
3854                         prev_eb = eb;
3855                         ret = lock_extent_buffer_for_io(eb, fs_info, &epd);
3856                         if (!ret) {
3857                                 free_extent_buffer(eb);
3858                                 continue;
3859                         }
3860
3861                         ret = write_one_eb(eb, fs_info, wbc, &epd);
3862                         if (ret) {
3863                                 done = 1;
3864                                 free_extent_buffer(eb);
3865                                 break;
3866                         }
3867                         free_extent_buffer(eb);
3868
3869                         /*
3870                          * the filesystem may choose to bump up nr_to_write.
3871                          * We have to make sure to honor the new nr_to_write
3872                          * at any time
3873                          */
3874                         nr_to_write_done = wbc->nr_to_write <= 0;
3875                 }
3876                 pagevec_release(&pvec);
3877                 cond_resched();
3878         }
3879         if (!scanned && !done) {
3880                 /*
3881                  * We hit the last page and there is more work to be done: wrap
3882                  * back to the start of the file
3883                  */
3884                 scanned = 1;
3885                 index = 0;
3886                 goto retry;
3887         }
3888         flush_write_bio(&epd);
3889         return ret;
3890 }
3891
3892 /**
3893  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
3894  * @mapping: address space structure to write
3895  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
3896  * @writepage: function called for each page
3897  * @data: data passed to writepage function
3898  *
3899  * If a page is already under I/O, write_cache_pages() skips it, even
3900  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
3901  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
3902  * and msync() need to guarantee that all the data which was dirty at the time
3903  * the call was made get new I/O started against them.  If wbc->sync_mode is
3904  * WB_SYNC_ALL then we were called for data integrity and we must wait for
3905  * existing IO to complete.
3906  */
3907 static int extent_write_cache_pages(struct extent_io_tree *tree,
3908                              struct address_space *mapping,
3909                              struct writeback_control *wbc,
3910                              writepage_t writepage, void *data,
3911                              void (*flush_fn)(void *))
3912 {
3913         struct inode *inode = mapping->host;
3914         int ret = 0;
3915         int done = 0;
3916         int nr_to_write_done = 0;
3917         struct pagevec pvec;
3918         int nr_pages;
3919         pgoff_t index;
3920         pgoff_t end;            /* Inclusive */
3921         pgoff_t done_index;
3922         int range_whole = 0;
3923         int scanned = 0;
3924         int tag;
3925
3926         /*
3927          * We have to hold onto the inode so that ordered extents can do their
3928          * work when the IO finishes.  The alternative to this is failing to add
3929          * an ordered extent if the igrab() fails there and that is a huge pain
3930          * to deal with, so instead just hold onto the inode throughout the
3931          * writepages operation.  If it fails here we are freeing up the inode
3932          * anyway and we'd rather not waste our time writing out stuff that is
3933          * going to be truncated anyway.
3934          */
3935         if (!igrab(inode))
3936                 return 0;
3937
3938         pagevec_init(&pvec, 0);
3939         if (wbc->range_cyclic) {
3940                 index = mapping->writeback_index; /* Start from prev offset */
3941                 end = -1;
3942         } else {
3943                 index = wbc->range_start >> PAGE_SHIFT;
3944                 end = wbc->range_end >> PAGE_SHIFT;
3945                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
3946                         range_whole = 1;
3947                 scanned = 1;
3948         }
3949         if (wbc->sync_mode == WB_SYNC_ALL)
3950                 tag = PAGECACHE_TAG_TOWRITE;
3951         else
3952                 tag = PAGECACHE_TAG_DIRTY;
3953 retry:
3954         if (wbc->sync_mode == WB_SYNC_ALL)
3955                 tag_pages_for_writeback(mapping, index, end);
3956         done_index = index;
3957         while (!done && !nr_to_write_done && (index <= end) &&
3958                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3959                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3960                 unsigned i;
3961
3962                 scanned = 1;
3963                 for (i = 0; i < nr_pages; i++) {
3964                         struct page *page = pvec.pages[i];
3965
3966                         done_index = page->index;
3967                         /*
3968                          * At this point we hold neither mapping->tree_lock nor
3969                          * lock on the page itself: the page may be truncated or
3970                          * invalidated (changing page->mapping to NULL), or even
3971                          * swizzled back from swapper_space to tmpfs file
3972                          * mapping
3973                          */
3974                         if (!trylock_page(page)) {
3975                                 flush_fn(data);
3976                                 lock_page(page);
3977                         }
3978
3979                         if (unlikely(page->mapping != mapping)) {
3980                                 unlock_page(page);
3981                                 continue;
3982                         }
3983
3984                         if (!wbc->range_cyclic && page->index > end) {
3985                                 done = 1;
3986                                 unlock_page(page);
3987                                 continue;
3988                         }
3989
3990                         if (wbc->sync_mode != WB_SYNC_NONE) {
3991                                 if (PageWriteback(page))
3992                                         flush_fn(data);
3993                                 wait_on_page_writeback(page);
3994                         }
3995
3996                         if (PageWriteback(page) ||
3997                             !clear_page_dirty_for_io(page)) {
3998                                 unlock_page(page);
3999                                 continue;
4000                         }
4001
4002                         ret = (*writepage)(page, wbc, data);
4003
4004                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
4005                                 unlock_page(page);
4006                                 ret = 0;
4007                         }
4008                         if (ret < 0) {
4009                                 /*
4010                                  * done_index is set past this page,
4011                                  * so media errors will not choke
4012                                  * background writeout for the entire
4013                                  * file. This has consequences for
4014                                  * range_cyclic semantics (ie. it may
4015                                  * not be suitable for data integrity
4016                                  * writeout).
4017                                  */
4018                                 done_index = page->index + 1;
4019                                 done = 1;
4020                                 break;
4021                         }
4022
4023                         /*
4024                          * the filesystem may choose to bump up nr_to_write.
4025                          * We have to make sure to honor the new nr_to_write
4026                          * at any time
4027                          */
4028                         nr_to_write_done = wbc->nr_to_write <= 0;
4029                 }
4030                 pagevec_release(&pvec);
4031                 cond_resched();
4032         }
4033         if (!scanned && !done) {
4034                 /*
4035                  * We hit the last page and there is more work to be done: wrap
4036                  * back to the start of the file
4037                  */
4038                 scanned = 1;
4039                 index = 0;
4040                 goto retry;
4041         }
4042
4043         if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole))
4044                 mapping->writeback_index = done_index;
4045
4046         btrfs_add_delayed_iput(inode);
4047         return ret;
4048 }
4049
4050 static void flush_epd_write_bio(struct extent_page_data *epd)
4051 {
4052         if (epd->bio) {
4053                 int ret;
4054
4055                 bio_set_op_attrs(epd->bio, REQ_OP_WRITE,
4056                                  epd->sync_io ? WRITE_SYNC : 0);
4057
4058                 ret = submit_one_bio(epd->bio, 0, epd->bio_flags);
4059                 BUG_ON(ret < 0); /* -ENOMEM */
4060                 epd->bio = NULL;
4061         }
4062 }
4063
4064 static noinline void flush_write_bio(void *data)
4065 {
4066         struct extent_page_data *epd = data;
4067         flush_epd_write_bio(epd);
4068 }
4069
4070 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
4071                           get_extent_t *get_extent,
4072                           struct writeback_control *wbc)
4073 {
4074         int ret;
4075         struct extent_page_data epd = {
4076                 .bio = NULL,
4077                 .tree = tree,
4078                 .get_extent = get_extent,
4079                 .extent_locked = 0,
4080                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4081                 .bio_flags = 0,
4082         };
4083
4084         ret = __extent_writepage(page, wbc, &epd);
4085
4086         flush_epd_write_bio(&epd);
4087         return ret;
4088 }
4089
4090 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
4091                               u64 start, u64 end, get_extent_t *get_extent,
4092                               int mode)
4093 {
4094         int ret = 0;
4095         struct address_space *mapping = inode->i_mapping;
4096         struct page *page;
4097         unsigned long nr_pages = (end - start + PAGE_SIZE) >>
4098                 PAGE_SHIFT;
4099
4100         struct extent_page_data epd = {
4101                 .bio = NULL,
4102                 .tree = tree,
4103                 .get_extent = get_extent,
4104                 .extent_locked = 1,
4105                 .sync_io = mode == WB_SYNC_ALL,
4106                 .bio_flags = 0,
4107         };
4108         struct writeback_control wbc_writepages = {
4109                 .sync_mode      = mode,
4110                 .nr_to_write    = nr_pages * 2,
4111                 .range_start    = start,
4112                 .range_end      = end + 1,
4113         };
4114
4115         while (start <= end) {
4116                 page = find_get_page(mapping, start >> PAGE_SHIFT);
4117                 if (clear_page_dirty_for_io(page))
4118                         ret = __extent_writepage(page, &wbc_writepages, &epd);
4119                 else {
4120                         if (tree->ops && tree->ops->writepage_end_io_hook)
4121                                 tree->ops->writepage_end_io_hook(page, start,
4122                                                  start + PAGE_SIZE - 1,
4123                                                  NULL, 1);
4124                         unlock_page(page);
4125                 }
4126                 put_page(page);
4127                 start += PAGE_SIZE;
4128         }
4129
4130         flush_epd_write_bio(&epd);
4131         return ret;
4132 }
4133
4134 int extent_writepages(struct extent_io_tree *tree,
4135                       struct address_space *mapping,
4136                       get_extent_t *get_extent,
4137                       struct writeback_control *wbc)
4138 {
4139         int ret = 0;
4140         struct extent_page_data epd = {
4141                 .bio = NULL,
4142                 .tree = tree,
4143                 .get_extent = get_extent,
4144                 .extent_locked = 0,
4145                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4146                 .bio_flags = 0,
4147         };
4148
4149         ret = extent_write_cache_pages(tree, mapping, wbc,
4150                                        __extent_writepage, &epd,
4151                                        flush_write_bio);
4152         flush_epd_write_bio(&epd);
4153         return ret;
4154 }
4155
4156 int extent_readpages(struct extent_io_tree *tree,
4157                      struct address_space *mapping,
4158                      struct list_head *pages, unsigned nr_pages,
4159                      get_extent_t get_extent)
4160 {
4161         struct bio *bio = NULL;
4162         unsigned page_idx;
4163         unsigned long bio_flags = 0;
4164         struct page *pagepool[16];
4165         struct page *page;
4166         struct extent_map *em_cached = NULL;
4167         int nr = 0;
4168         u64 prev_em_start = (u64)-1;
4169
4170         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
4171                 page = list_entry(pages->prev, struct page, lru);
4172
4173                 prefetchw(&page->flags);
4174                 list_del(&page->lru);
4175                 if (add_to_page_cache_lru(page, mapping,
4176                                         page->index,
4177                                         readahead_gfp_mask(mapping))) {
4178                         put_page(page);
4179                         continue;
4180                 }
4181
4182                 pagepool[nr++] = page;
4183                 if (nr < ARRAY_SIZE(pagepool))
4184                         continue;
4185                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4186                                    &bio, 0, &bio_flags, &prev_em_start);
4187                 nr = 0;
4188         }
4189         if (nr)
4190                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4191                                    &bio, 0, &bio_flags, &prev_em_start);
4192
4193         if (em_cached)
4194                 free_extent_map(em_cached);
4195
4196         BUG_ON(!list_empty(pages));
4197         if (bio)
4198                 return submit_one_bio(bio, 0, bio_flags);
4199         return 0;
4200 }
4201
4202 /*
4203  * basic invalidatepage code, this waits on any locked or writeback
4204  * ranges corresponding to the page, and then deletes any extent state
4205  * records from the tree
4206  */
4207 int extent_invalidatepage(struct extent_io_tree *tree,
4208                           struct page *page, unsigned long offset)
4209 {
4210         struct extent_state *cached_state = NULL;
4211         u64 start = page_offset(page);
4212         u64 end = start + PAGE_SIZE - 1;
4213         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
4214
4215         start += ALIGN(offset, blocksize);
4216         if (start > end)
4217                 return 0;
4218
4219         lock_extent_bits(tree, start, end, &cached_state);
4220         wait_on_page_writeback(page);
4221         clear_extent_bit(tree, start, end,
4222                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
4223                          EXTENT_DO_ACCOUNTING,
4224                          1, 1, &cached_state, GFP_NOFS);
4225         return 0;
4226 }
4227
4228 /*
4229  * a helper for releasepage, this tests for areas of the page that
4230  * are locked or under IO and drops the related state bits if it is safe
4231  * to drop the page.
4232  */
4233 static int try_release_extent_state(struct extent_map_tree *map,
4234                                     struct extent_io_tree *tree,
4235                                     struct page *page, gfp_t mask)
4236 {
4237         u64 start = page_offset(page);
4238         u64 end = start + PAGE_SIZE - 1;
4239         int ret = 1;
4240
4241         if (test_range_bit(tree, start, end,
4242                            EXTENT_IOBITS, 0, NULL))
4243                 ret = 0;
4244         else {
4245                 if ((mask & GFP_NOFS) == GFP_NOFS)
4246                         mask = GFP_NOFS;
4247                 /*
4248                  * at this point we can safely clear everything except the
4249                  * locked bit and the nodatasum bit
4250                  */
4251                 ret = clear_extent_bit(tree, start, end,
4252                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
4253                                  0, 0, NULL, mask);
4254
4255                 /* if clear_extent_bit failed for enomem reasons,
4256                  * we can't allow the release to continue.
4257                  */
4258                 if (ret < 0)
4259                         ret = 0;
4260                 else
4261                         ret = 1;
4262         }
4263         return ret;
4264 }
4265
4266 /*
4267  * a helper for releasepage.  As long as there are no locked extents
4268  * in the range corresponding to the page, both state records and extent
4269  * map records are removed
4270  */
4271 int try_release_extent_mapping(struct extent_map_tree *map,
4272                                struct extent_io_tree *tree, struct page *page,
4273                                gfp_t mask)
4274 {
4275         struct extent_map *em;
4276         u64 start = page_offset(page);
4277         u64 end = start + PAGE_SIZE - 1;
4278
4279         if (gfpflags_allow_blocking(mask) &&
4280             page->mapping->host->i_size > SZ_16M) {
4281                 u64 len;
4282                 while (start <= end) {
4283                         len = end - start + 1;
4284                         write_lock(&map->lock);
4285                         em = lookup_extent_mapping(map, start, len);
4286                         if (!em) {
4287                                 write_unlock(&map->lock);
4288                                 break;
4289                         }
4290                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
4291                             em->start != start) {
4292                                 write_unlock(&map->lock);
4293                                 free_extent_map(em);
4294                                 break;
4295                         }
4296                         if (!test_range_bit(tree, em->start,
4297                                             extent_map_end(em) - 1,
4298                                             EXTENT_LOCKED | EXTENT_WRITEBACK,
4299                                             0, NULL)) {
4300                                 remove_extent_mapping(map, em);
4301                                 /* once for the rb tree */
4302                                 free_extent_map(em);
4303                         }
4304                         start = extent_map_end(em);
4305                         write_unlock(&map->lock);
4306
4307                         /* once for us */
4308                         free_extent_map(em);
4309                 }
4310         }
4311         return try_release_extent_state(map, tree, page, mask);
4312 }
4313
4314 /*
4315  * helper function for fiemap, which doesn't want to see any holes.
4316  * This maps until we find something past 'last'
4317  */
4318 static struct extent_map *get_extent_skip_holes(struct inode *inode,
4319                                                 u64 offset,
4320                                                 u64 last,
4321                                                 get_extent_t *get_extent)
4322 {
4323         u64 sectorsize = BTRFS_I(inode)->root->sectorsize;
4324         struct extent_map *em;
4325         u64 len;
4326
4327         if (offset >= last)
4328                 return NULL;
4329
4330         while (1) {
4331                 len = last - offset;
4332                 if (len == 0)
4333                         break;
4334                 len = ALIGN(len, sectorsize);
4335                 em = get_extent(inode, NULL, 0, offset, len, 0);
4336                 if (IS_ERR_OR_NULL(em))
4337                         return em;
4338
4339                 /* if this isn't a hole return it */
4340                 if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
4341                     em->block_start != EXTENT_MAP_HOLE) {
4342                         return em;
4343                 }
4344
4345                 /* this is a hole, advance to the next extent */
4346                 offset = extent_map_end(em);
4347                 free_extent_map(em);
4348                 if (offset >= last)
4349                         break;
4350         }
4351         return NULL;
4352 }
4353
4354 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
4355                 __u64 start, __u64 len, get_extent_t *get_extent)
4356 {
4357         int ret = 0;
4358         u64 off = start;
4359         u64 max = start + len;
4360         u32 flags = 0;
4361         u32 found_type;
4362         u64 last;
4363         u64 last_for_get_extent = 0;
4364         u64 disko = 0;
4365         u64 isize = i_size_read(inode);
4366         struct btrfs_key found_key;
4367         struct extent_map *em = NULL;
4368         struct extent_state *cached_state = NULL;
4369         struct btrfs_path *path;
4370         struct btrfs_root *root = BTRFS_I(inode)->root;
4371         int end = 0;
4372         u64 em_start = 0;
4373         u64 em_len = 0;
4374         u64 em_end = 0;
4375
4376         if (len == 0)
4377                 return -EINVAL;
4378
4379         path = btrfs_alloc_path();
4380         if (!path)
4381                 return -ENOMEM;
4382         path->leave_spinning = 1;
4383
4384         start = round_down(start, BTRFS_I(inode)->root->sectorsize);
4385         len = round_up(max, BTRFS_I(inode)->root->sectorsize) - start;
4386
4387         /*
4388          * lookup the last file extent.  We're not using i_size here
4389          * because there might be preallocation past i_size
4390          */
4391         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode), -1,
4392                                        0);
4393         if (ret < 0) {
4394                 btrfs_free_path(path);
4395                 return ret;
4396         } else {
4397                 WARN_ON(!ret);
4398                 if (ret == 1)
4399                         ret = 0;
4400         }
4401
4402         path->slots[0]--;
4403         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
4404         found_type = found_key.type;
4405
4406         /* No extents, but there might be delalloc bits */
4407         if (found_key.objectid != btrfs_ino(inode) ||
4408             found_type != BTRFS_EXTENT_DATA_KEY) {
4409                 /* have to trust i_size as the end */
4410                 last = (u64)-1;
4411                 last_for_get_extent = isize;
4412         } else {
4413                 /*
4414                  * remember the start of the last extent.  There are a
4415                  * bunch of different factors that go into the length of the
4416                  * extent, so its much less complex to remember where it started
4417                  */
4418                 last = found_key.offset;
4419                 last_for_get_extent = last + 1;
4420         }
4421         btrfs_release_path(path);
4422
4423         /*
4424          * we might have some extents allocated but more delalloc past those
4425          * extents.  so, we trust isize unless the start of the last extent is
4426          * beyond isize
4427          */
4428         if (last < isize) {
4429                 last = (u64)-1;
4430                 last_for_get_extent = isize;
4431         }
4432
4433         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4434                          &cached_state);
4435
4436         em = get_extent_skip_holes(inode, start, last_for_get_extent,
4437                                    get_extent);
4438         if (!em)
4439                 goto out;
4440         if (IS_ERR(em)) {
4441                 ret = PTR_ERR(em);
4442                 goto out;
4443         }
4444
4445         while (!end) {
4446                 u64 offset_in_extent = 0;
4447
4448                 /* break if the extent we found is outside the range */
4449                 if (em->start >= max || extent_map_end(em) < off)
4450                         break;
4451
4452                 /*
4453                  * get_extent may return an extent that starts before our
4454                  * requested range.  We have to make sure the ranges
4455                  * we return to fiemap always move forward and don't
4456                  * overlap, so adjust the offsets here
4457                  */
4458                 em_start = max(em->start, off);
4459
4460                 /*
4461                  * record the offset from the start of the extent
4462                  * for adjusting the disk offset below.  Only do this if the
4463                  * extent isn't compressed since our in ram offset may be past
4464                  * what we have actually allocated on disk.
4465                  */
4466                 if (!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4467                         offset_in_extent = em_start - em->start;
4468                 em_end = extent_map_end(em);
4469                 em_len = em_end - em_start;
4470                 disko = 0;
4471                 flags = 0;
4472
4473                 /*
4474                  * bump off for our next call to get_extent
4475                  */
4476                 off = extent_map_end(em);
4477                 if (off >= max)
4478                         end = 1;
4479
4480                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
4481                         end = 1;
4482                         flags |= FIEMAP_EXTENT_LAST;
4483                 } else if (em->block_start == EXTENT_MAP_INLINE) {
4484                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
4485                                   FIEMAP_EXTENT_NOT_ALIGNED);
4486                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
4487                         flags |= (FIEMAP_EXTENT_DELALLOC |
4488                                   FIEMAP_EXTENT_UNKNOWN);
4489                 } else if (fieinfo->fi_extents_max) {
4490                         struct btrfs_trans_handle *trans;
4491
4492                         u64 bytenr = em->block_start -
4493                                 (em->start - em->orig_start);
4494
4495                         disko = em->block_start + offset_in_extent;
4496
4497                         /*
4498                          * We need a trans handle to get delayed refs
4499                          */
4500                         trans = btrfs_join_transaction(root);
4501                         /*
4502                          * It's OK if we can't start a trans we can still check
4503                          * from commit_root
4504                          */
4505                         if (IS_ERR(trans))
4506                                 trans = NULL;
4507
4508                         /*
4509                          * As btrfs supports shared space, this information
4510                          * can be exported to userspace tools via
4511                          * flag FIEMAP_EXTENT_SHARED.  If fi_extents_max == 0
4512                          * then we're just getting a count and we can skip the
4513                          * lookup stuff.
4514                          */
4515                         ret = btrfs_check_shared(trans, root->fs_info,
4516                                                  root->objectid,
4517                                                  btrfs_ino(inode), bytenr);
4518                         if (trans)
4519                                 btrfs_end_transaction(trans, root);
4520                         if (ret < 0)
4521                                 goto out_free;
4522                         if (ret)
4523                                 flags |= FIEMAP_EXTENT_SHARED;
4524                         ret = 0;
4525                 }
4526                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4527                         flags |= FIEMAP_EXTENT_ENCODED;
4528                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
4529                         flags |= FIEMAP_EXTENT_UNWRITTEN;
4530
4531                 free_extent_map(em);
4532                 em = NULL;
4533                 if ((em_start >= last) || em_len == (u64)-1 ||
4534                    (last == (u64)-1 && isize <= em_end)) {
4535                         flags |= FIEMAP_EXTENT_LAST;
4536                         end = 1;
4537                 }
4538
4539                 /* now scan forward to see if this is really the last extent. */
4540                 em = get_extent_skip_holes(inode, off, last_for_get_extent,
4541                                            get_extent);
4542                 if (IS_ERR(em)) {
4543                         ret = PTR_ERR(em);
4544                         goto out;
4545                 }
4546                 if (!em) {
4547                         flags |= FIEMAP_EXTENT_LAST;
4548                         end = 1;
4549                 }
4550                 ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
4551                                               em_len, flags);
4552                 if (ret) {
4553                         if (ret == 1)
4554                                 ret = 0;
4555                         goto out_free;
4556                 }
4557         }
4558 out_free:
4559         free_extent_map(em);
4560 out:
4561         btrfs_free_path(path);
4562         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4563                              &cached_state, GFP_NOFS);
4564         return ret;
4565 }
4566
4567 static void __free_extent_buffer(struct extent_buffer *eb)
4568 {
4569         btrfs_leak_debug_del(&eb->leak_list);
4570         kmem_cache_free(extent_buffer_cache, eb);
4571 }
4572
4573 int extent_buffer_under_io(struct extent_buffer *eb)
4574 {
4575         return (atomic_read(&eb->io_pages) ||
4576                 test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
4577                 test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4578 }
4579
4580 /*
4581  * Helper for releasing extent buffer page.
4582  */
4583 static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
4584 {
4585         unsigned long index;
4586         struct page *page;
4587         int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4588
4589         BUG_ON(extent_buffer_under_io(eb));
4590
4591         index = num_extent_pages(eb->start, eb->len);
4592         if (index == 0)
4593                 return;
4594
4595         do {
4596                 index--;
4597                 page = eb->pages[index];
4598                 if (!page)
4599                         continue;
4600                 if (mapped)
4601                         spin_lock(&page->mapping->private_lock);
4602                 /*
4603                  * We do this since we'll remove the pages after we've
4604                  * removed the eb from the radix tree, so we could race
4605                  * and have this page now attached to the new eb.  So
4606                  * only clear page_private if it's still connected to
4607                  * this eb.
4608                  */
4609                 if (PagePrivate(page) &&
4610                     page->private == (unsigned long)eb) {
4611                         BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4612                         BUG_ON(PageDirty(page));
4613                         BUG_ON(PageWriteback(page));
4614                         /*
4615                          * We need to make sure we haven't be attached
4616                          * to a new eb.
4617                          */
4618                         ClearPagePrivate(page);
4619                         set_page_private(page, 0);
4620                         /* One for the page private */
4621                         put_page(page);
4622                 }
4623
4624                 if (mapped)
4625                         spin_unlock(&page->mapping->private_lock);
4626
4627                 /* One for when we allocated the page */
4628                 put_page(page);
4629         } while (index != 0);
4630 }
4631
4632 /*
4633  * Helper for releasing the extent buffer.
4634  */
4635 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
4636 {
4637         btrfs_release_extent_buffer_page(eb);
4638         __free_extent_buffer(eb);
4639 }
4640
4641 static struct extent_buffer *
4642 __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
4643                       unsigned long len)
4644 {
4645         struct extent_buffer *eb = NULL;
4646
4647         eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
4648         eb->start = start;
4649         eb->len = len;
4650         eb->fs_info = fs_info;
4651         eb->bflags = 0;
4652         rwlock_init(&eb->lock);
4653         atomic_set(&eb->write_locks, 0);
4654         atomic_set(&eb->read_locks, 0);
4655         atomic_set(&eb->blocking_readers, 0);
4656         atomic_set(&eb->blocking_writers, 0);
4657         atomic_set(&eb->spinning_readers, 0);
4658         atomic_set(&eb->spinning_writers, 0);
4659         eb->lock_nested = 0;
4660         init_waitqueue_head(&eb->write_lock_wq);
4661         init_waitqueue_head(&eb->read_lock_wq);
4662
4663         btrfs_leak_debug_add(&eb->leak_list, &buffers);
4664
4665         spin_lock_init(&eb->refs_lock);
4666         atomic_set(&eb->refs, 1);
4667         atomic_set(&eb->io_pages, 0);
4668
4669         /*
4670          * Sanity checks, currently the maximum is 64k covered by 16x 4k pages
4671          */
4672         BUILD_BUG_ON(BTRFS_MAX_METADATA_BLOCKSIZE
4673                 > MAX_INLINE_EXTENT_BUFFER_SIZE);
4674         BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
4675
4676         return eb;
4677 }
4678
4679 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
4680 {
4681         unsigned long i;
4682         struct page *p;
4683         struct extent_buffer *new;
4684         unsigned long num_pages = num_extent_pages(src->start, src->len);
4685
4686         new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
4687         if (new == NULL)
4688                 return NULL;
4689
4690         for (i = 0; i < num_pages; i++) {
4691                 p = alloc_page(GFP_NOFS);
4692                 if (!p) {
4693                         btrfs_release_extent_buffer(new);
4694                         return NULL;
4695                 }
4696                 attach_extent_buffer_page(new, p);
4697                 WARN_ON(PageDirty(p));
4698                 SetPageUptodate(p);
4699                 new->pages[i] = p;
4700         }
4701
4702         copy_extent_buffer(new, src, 0, 0, src->len);
4703         set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
4704         set_bit(EXTENT_BUFFER_DUMMY, &new->bflags);
4705
4706         return new;
4707 }
4708
4709 struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4710                                                   u64 start, unsigned long len)
4711 {
4712         struct extent_buffer *eb;
4713         unsigned long num_pages;
4714         unsigned long i;
4715
4716         num_pages = num_extent_pages(start, len);
4717
4718         eb = __alloc_extent_buffer(fs_info, start, len);
4719         if (!eb)
4720                 return NULL;
4721
4722         for (i = 0; i < num_pages; i++) {
4723                 eb->pages[i] = alloc_page(GFP_NOFS);
4724                 if (!eb->pages[i])
4725                         goto err;
4726         }
4727         set_extent_buffer_uptodate(eb);
4728         btrfs_set_header_nritems(eb, 0);
4729         set_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4730
4731         return eb;
4732 err:
4733         for (; i > 0; i--)
4734                 __free_page(eb->pages[i - 1]);
4735         __free_extent_buffer(eb);
4736         return NULL;
4737 }
4738
4739 struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4740                                                 u64 start, u32 nodesize)
4741 {
4742         unsigned long len;
4743
4744         if (!fs_info) {
4745                 /*
4746                  * Called only from tests that don't always have a fs_info
4747                  * available
4748                  */
4749                 len = nodesize;
4750         } else {
4751                 len = fs_info->tree_root->nodesize;
4752         }
4753
4754         return __alloc_dummy_extent_buffer(fs_info, start, len);
4755 }
4756
4757 static void check_buffer_tree_ref(struct extent_buffer *eb)
4758 {
4759         int refs;
4760         /* the ref bit is tricky.  We have to make sure it is set
4761          * if we have the buffer dirty.   Otherwise the
4762          * code to free a buffer can end up dropping a dirty
4763          * page
4764          *
4765          * Once the ref bit is set, it won't go away while the
4766          * buffer is dirty or in writeback, and it also won't
4767          * go away while we have the reference count on the
4768          * eb bumped.
4769          *
4770          * We can't just set the ref bit without bumping the
4771          * ref on the eb because free_extent_buffer might
4772          * see the ref bit and try to clear it.  If this happens
4773          * free_extent_buffer might end up dropping our original
4774          * ref by mistake and freeing the page before we are able
4775          * to add one more ref.
4776          *
4777          * So bump the ref count first, then set the bit.  If someone
4778          * beat us to it, drop the ref we added.
4779          */
4780         refs = atomic_read(&eb->refs);
4781         if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4782                 return;
4783
4784         spin_lock(&eb->refs_lock);
4785         if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4786                 atomic_inc(&eb->refs);
4787         spin_unlock(&eb->refs_lock);
4788 }
4789
4790 static void mark_extent_buffer_accessed(struct extent_buffer *eb,
4791                 struct page *accessed)
4792 {
4793         unsigned long num_pages, i;
4794
4795         check_buffer_tree_ref(eb);
4796
4797         num_pages = num_extent_pages(eb->start, eb->len);
4798         for (i = 0; i < num_pages; i++) {
4799                 struct page *p = eb->pages[i];
4800
4801                 if (p != accessed)
4802                         mark_page_accessed(p);
4803         }
4804 }
4805
4806 struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
4807                                          u64 start)
4808 {
4809         struct extent_buffer *eb;
4810
4811         rcu_read_lock();
4812         eb = radix_tree_lookup(&fs_info->buffer_radix,
4813                                start >> PAGE_SHIFT);
4814         if (eb && atomic_inc_not_zero(&eb->refs)) {
4815                 rcu_read_unlock();
4816                 /*
4817                  * Lock our eb's refs_lock to avoid races with
4818                  * free_extent_buffer. When we get our eb it might be flagged
4819                  * with EXTENT_BUFFER_STALE and another task running
4820                  * free_extent_buffer might have seen that flag set,
4821                  * eb->refs == 2, that the buffer isn't under IO (dirty and
4822                  * writeback flags not set) and it's still in the tree (flag
4823                  * EXTENT_BUFFER_TREE_REF set), therefore being in the process
4824                  * of decrementing the extent buffer's reference count twice.
4825                  * So here we could race and increment the eb's reference count,
4826                  * clear its stale flag, mark it as dirty and drop our reference
4827                  * before the other task finishes executing free_extent_buffer,
4828                  * which would later result in an attempt to free an extent
4829                  * buffer that is dirty.
4830                  */
4831                 if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
4832                         spin_lock(&eb->refs_lock);
4833                         spin_unlock(&eb->refs_lock);
4834                 }
4835                 mark_extent_buffer_accessed(eb, NULL);
4836                 return eb;
4837         }
4838         rcu_read_unlock();
4839
4840         return NULL;
4841 }
4842
4843 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
4844 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
4845                                         u64 start, u32 nodesize)
4846 {
4847         struct extent_buffer *eb, *exists = NULL;
4848         int ret;
4849
4850         eb = find_extent_buffer(fs_info, start);
4851         if (eb)
4852                 return eb;
4853         eb = alloc_dummy_extent_buffer(fs_info, start, nodesize);
4854         if (!eb)
4855                 return NULL;
4856         eb->fs_info = fs_info;
4857 again:
4858         ret = radix_tree_preload(GFP_NOFS);
4859         if (ret)
4860                 goto free_eb;
4861         spin_lock(&fs_info->buffer_lock);
4862         ret = radix_tree_insert(&fs_info->buffer_radix,
4863                                 start >> PAGE_SHIFT, eb);
4864         spin_unlock(&fs_info->buffer_lock);
4865         radix_tree_preload_end();
4866         if (ret == -EEXIST) {
4867                 exists = find_extent_buffer(fs_info, start);
4868                 if (exists)
4869                         goto free_eb;
4870                 else
4871                         goto again;
4872         }
4873         check_buffer_tree_ref(eb);
4874         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4875
4876         /*
4877          * We will free dummy extent buffer's if they come into
4878          * free_extent_buffer with a ref count of 2, but if we are using this we
4879          * want the buffers to stay in memory until we're done with them, so
4880          * bump the ref count again.
4881          */
4882         atomic_inc(&eb->refs);
4883         return eb;
4884 free_eb:
4885         btrfs_release_extent_buffer(eb);
4886         return exists;
4887 }
4888 #endif
4889
4890 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
4891                                           u64 start)
4892 {
4893         unsigned long len = fs_info->tree_root->nodesize;
4894         unsigned long num_pages = num_extent_pages(start, len);
4895         unsigned long i;
4896         unsigned long index = start >> PAGE_SHIFT;
4897         struct extent_buffer *eb;
4898         struct extent_buffer *exists = NULL;
4899         struct page *p;
4900         struct address_space *mapping = fs_info->btree_inode->i_mapping;
4901         int uptodate = 1;
4902         int ret;
4903
4904         if (!IS_ALIGNED(start, fs_info->tree_root->sectorsize)) {
4905                 btrfs_err(fs_info, "bad tree block start %llu", start);
4906                 return ERR_PTR(-EINVAL);
4907         }
4908
4909         eb = find_extent_buffer(fs_info, start);
4910         if (eb)
4911                 return eb;
4912
4913         eb = __alloc_extent_buffer(fs_info, start, len);
4914         if (!eb)
4915                 return ERR_PTR(-ENOMEM);
4916
4917         for (i = 0; i < num_pages; i++, index++) {
4918                 p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL);
4919                 if (!p) {
4920                         exists = ERR_PTR(-ENOMEM);
4921                         goto free_eb;
4922                 }
4923
4924                 spin_lock(&mapping->private_lock);
4925                 if (PagePrivate(p)) {
4926                         /*
4927                          * We could have already allocated an eb for this page
4928                          * and attached one so lets see if we can get a ref on
4929                          * the existing eb, and if we can we know it's good and
4930                          * we can just return that one, else we know we can just
4931                          * overwrite page->private.
4932                          */
4933                         exists = (struct extent_buffer *)p->private;
4934                         if (atomic_inc_not_zero(&exists->refs)) {
4935                                 spin_unlock(&mapping->private_lock);
4936                                 unlock_page(p);
4937                                 put_page(p);
4938                                 mark_extent_buffer_accessed(exists, p);
4939                                 goto free_eb;
4940                         }
4941                         exists = NULL;
4942
4943                         /*
4944                          * Do this so attach doesn't complain and we need to
4945                          * drop the ref the old guy had.
4946                          */
4947                         ClearPagePrivate(p);
4948                         WARN_ON(PageDirty(p));
4949                         put_page(p);
4950                 }
4951                 attach_extent_buffer_page(eb, p);
4952                 spin_unlock(&mapping->private_lock);
4953                 WARN_ON(PageDirty(p));
4954                 eb->pages[i] = p;
4955                 if (!PageUptodate(p))
4956                         uptodate = 0;
4957
4958                 /*
4959                  * see below about how we avoid a nasty race with release page
4960                  * and why we unlock later
4961                  */
4962         }
4963         if (uptodate)
4964                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
4965 again:
4966         ret = radix_tree_preload(GFP_NOFS);
4967         if (ret) {
4968                 exists = ERR_PTR(ret);
4969                 goto free_eb;
4970         }
4971
4972         spin_lock(&fs_info->buffer_lock);
4973         ret = radix_tree_insert(&fs_info->buffer_radix,
4974                                 start >> PAGE_SHIFT, eb);
4975         spin_unlock(&fs_info->buffer_lock);
4976         radix_tree_preload_end();
4977         if (ret == -EEXIST) {
4978                 exists = find_extent_buffer(fs_info, start);
4979                 if (exists)
4980                         goto free_eb;
4981                 else
4982                         goto again;
4983         }
4984         /* add one reference for the tree */
4985         check_buffer_tree_ref(eb);
4986         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4987
4988         /*
4989          * there is a race where release page may have
4990          * tried to find this extent buffer in the radix
4991          * but failed.  It will tell the VM it is safe to
4992          * reclaim the, and it will clear the page private bit.
4993          * We must make sure to set the page private bit properly
4994          * after the extent buffer is in the radix tree so
4995          * it doesn't get lost
4996          */
4997         SetPageChecked(eb->pages[0]);
4998         for (i = 1; i < num_pages; i++) {
4999                 p = eb->pages[i];
5000                 ClearPageChecked(p);
5001                 unlock_page(p);
5002         }
5003         unlock_page(eb->pages[0]);
5004         return eb;
5005
5006 free_eb:
5007         WARN_ON(!atomic_dec_and_test(&eb->refs));
5008         for (i = 0; i < num_pages; i++) {
5009                 if (eb->pages[i])
5010                         unlock_page(eb->pages[i]);
5011         }
5012
5013         btrfs_release_extent_buffer(eb);
5014         return exists;
5015 }
5016
5017 static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
5018 {
5019         struct extent_buffer *eb =
5020                         container_of(head, struct extent_buffer, rcu_head);
5021
5022         __free_extent_buffer(eb);
5023 }
5024
5025 /* Expects to have eb->eb_lock already held */
5026 static int release_extent_buffer(struct extent_buffer *eb)
5027 {
5028         WARN_ON(atomic_read(&eb->refs) == 0);
5029         if (atomic_dec_and_test(&eb->refs)) {
5030                 if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) {
5031                         struct btrfs_fs_info *fs_info = eb->fs_info;
5032
5033                         spin_unlock(&eb->refs_lock);
5034
5035                         spin_lock(&fs_info->buffer_lock);
5036                         radix_tree_delete(&fs_info->buffer_radix,
5037                                           eb->start >> PAGE_SHIFT);
5038                         spin_unlock(&fs_info->buffer_lock);
5039                 } else {
5040                         spin_unlock(&eb->refs_lock);
5041                 }
5042
5043                 /* Should be safe to release our pages at this point */
5044                 btrfs_release_extent_buffer_page(eb);
5045 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
5046                 if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))) {
5047                         __free_extent_buffer(eb);
5048                         return 1;
5049                 }
5050 #endif
5051                 call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
5052                 return 1;
5053         }
5054         spin_unlock(&eb->refs_lock);
5055
5056         return 0;
5057 }
5058
5059 void free_extent_buffer(struct extent_buffer *eb)
5060 {
5061         int refs;
5062         int old;
5063         if (!eb)
5064                 return;
5065
5066         while (1) {
5067                 refs = atomic_read(&eb->refs);
5068                 if (refs <= 3)
5069                         break;
5070                 old = atomic_cmpxchg(&eb->refs, refs, refs - 1);
5071                 if (old == refs)
5072                         return;
5073         }
5074
5075         spin_lock(&eb->refs_lock);
5076         if (atomic_read(&eb->refs) == 2 &&
5077             test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))
5078                 atomic_dec(&eb->refs);
5079
5080         if (atomic_read(&eb->refs) == 2 &&
5081             test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
5082             !extent_buffer_under_io(eb) &&
5083             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5084                 atomic_dec(&eb->refs);
5085
5086         /*
5087          * I know this is terrible, but it's temporary until we stop tracking
5088          * the uptodate bits and such for the extent buffers.
5089          */
5090         release_extent_buffer(eb);
5091 }
5092
5093 void free_extent_buffer_stale(struct extent_buffer *eb)
5094 {
5095         if (!eb)
5096                 return;
5097
5098         spin_lock(&eb->refs_lock);
5099         set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
5100
5101         if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
5102             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5103                 atomic_dec(&eb->refs);
5104         release_extent_buffer(eb);
5105 }
5106
5107 void clear_extent_buffer_dirty(struct extent_buffer *eb)
5108 {
5109         unsigned long i;
5110         unsigned long num_pages;
5111         struct page *page;
5112
5113         num_pages = num_extent_pages(eb->start, eb->len);
5114
5115         for (i = 0; i < num_pages; i++) {
5116                 page = eb->pages[i];
5117                 if (!PageDirty(page))
5118                         continue;
5119
5120                 lock_page(page);
5121                 WARN_ON(!PagePrivate(page));
5122
5123                 clear_page_dirty_for_io(page);
5124                 spin_lock_irq(&page->mapping->tree_lock);
5125                 if (!PageDirty(page)) {
5126                         radix_tree_tag_clear(&page->mapping->page_tree,
5127                                                 page_index(page),
5128                                                 PAGECACHE_TAG_DIRTY);
5129                 }
5130                 spin_unlock_irq(&page->mapping->tree_lock);
5131                 ClearPageError(page);
5132                 unlock_page(page);
5133         }
5134         WARN_ON(atomic_read(&eb->refs) == 0);
5135 }
5136
5137 int set_extent_buffer_dirty(struct extent_buffer *eb)
5138 {
5139         unsigned long i;
5140         unsigned long num_pages;
5141         int was_dirty = 0;
5142
5143         check_buffer_tree_ref(eb);
5144
5145         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
5146
5147         num_pages = num_extent_pages(eb->start, eb->len);
5148         WARN_ON(atomic_read(&eb->refs) == 0);
5149         WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
5150
5151         for (i = 0; i < num_pages; i++)
5152                 set_page_dirty(eb->pages[i]);
5153         return was_dirty;
5154 }
5155
5156 void clear_extent_buffer_uptodate(struct extent_buffer *eb)
5157 {
5158         unsigned long i;
5159         struct page *page;
5160         unsigned long num_pages;
5161
5162         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5163         num_pages = num_extent_pages(eb->start, eb->len);
5164         for (i = 0; i < num_pages; i++) {
5165                 page = eb->pages[i];
5166                 if (page)
5167                         ClearPageUptodate(page);
5168         }
5169 }
5170
5171 void set_extent_buffer_uptodate(struct extent_buffer *eb)
5172 {
5173         unsigned long i;
5174         struct page *page;
5175         unsigned long num_pages;
5176
5177         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5178         num_pages = num_extent_pages(eb->start, eb->len);
5179         for (i = 0; i < num_pages; i++) {
5180                 page = eb->pages[i];
5181                 SetPageUptodate(page);
5182         }
5183 }
5184
5185 int extent_buffer_uptodate(struct extent_buffer *eb)
5186 {
5187         return test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5188 }
5189
5190 int read_extent_buffer_pages(struct extent_io_tree *tree,
5191                              struct extent_buffer *eb, u64 start, int wait,
5192                              get_extent_t *get_extent, int mirror_num)
5193 {
5194         unsigned long i;
5195         unsigned long start_i;
5196         struct page *page;
5197         int err;
5198         int ret = 0;
5199         int locked_pages = 0;
5200         int all_uptodate = 1;
5201         unsigned long num_pages;
5202         unsigned long num_reads = 0;
5203         struct bio *bio = NULL;
5204         unsigned long bio_flags = 0;
5205
5206         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
5207                 return 0;
5208
5209         if (start) {
5210                 WARN_ON(start < eb->start);
5211                 start_i = (start >> PAGE_SHIFT) -
5212                         (eb->start >> PAGE_SHIFT);
5213         } else {
5214                 start_i = 0;
5215         }
5216
5217         num_pages = num_extent_pages(eb->start, eb->len);
5218         for (i = start_i; i < num_pages; i++) {
5219                 page = eb->pages[i];
5220                 if (wait == WAIT_NONE) {
5221                         if (!trylock_page(page))
5222                                 goto unlock_exit;
5223                 } else {
5224                         lock_page(page);
5225                 }
5226                 locked_pages++;
5227         }
5228         /*
5229          * We need to firstly lock all pages to make sure that
5230          * the uptodate bit of our pages won't be affected by
5231          * clear_extent_buffer_uptodate().
5232          */
5233         for (i = start_i; i < num_pages; i++) {
5234                 page = eb->pages[i];
5235                 if (!PageUptodate(page)) {
5236                         num_reads++;
5237                         all_uptodate = 0;
5238                 }
5239         }
5240
5241         if (all_uptodate) {
5242                 if (start_i == 0)
5243                         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5244                 goto unlock_exit;
5245         }
5246
5247         clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
5248         eb->read_mirror = 0;
5249         atomic_set(&eb->io_pages, num_reads);
5250         for (i = start_i; i < num_pages; i++) {
5251                 page = eb->pages[i];
5252
5253                 if (!PageUptodate(page)) {
5254                         if (ret) {
5255                                 atomic_dec(&eb->io_pages);
5256                                 unlock_page(page);
5257                                 continue;
5258                         }
5259
5260                         ClearPageError(page);
5261                         err = __extent_read_full_page(tree, page,
5262                                                       get_extent, &bio,
5263                                                       mirror_num, &bio_flags,
5264                                                       REQ_META);
5265                         if (err) {
5266                                 ret = err;
5267                                 /*
5268                                  * We use &bio in above __extent_read_full_page,
5269                                  * so we ensure that if it returns error, the
5270                                  * current page fails to add itself to bio and
5271                                  * it's been unlocked.
5272                                  *
5273                                  * We must dec io_pages by ourselves.
5274                                  */
5275                                 atomic_dec(&eb->io_pages);
5276                         }
5277                 } else {
5278                         unlock_page(page);
5279                 }
5280         }
5281
5282         if (bio) {
5283                 err = submit_one_bio(bio, mirror_num, bio_flags);
5284                 if (err)
5285                         return err;
5286         }
5287
5288         if (ret || wait != WAIT_COMPLETE)
5289                 return ret;
5290
5291         for (i = start_i; i < num_pages; i++) {
5292                 page = eb->pages[i];
5293                 wait_on_page_locked(page);
5294                 if (!PageUptodate(page))
5295                         ret = -EIO;
5296         }
5297
5298         return ret;
5299
5300 unlock_exit:
5301         i = start_i;
5302         while (locked_pages > 0) {
5303                 page = eb->pages[i];
5304                 i++;
5305                 unlock_page(page);
5306                 locked_pages--;
5307         }
5308         return ret;
5309 }
5310
5311 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
5312                         unsigned long start,
5313                         unsigned long len)
5314 {
5315         size_t cur;
5316         size_t offset;
5317         struct page *page;
5318         char *kaddr;
5319         char *dst = (char *)dstv;
5320         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5321         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5322
5323         WARN_ON(start > eb->len);
5324         WARN_ON(start + len > eb->start + eb->len);
5325
5326         offset = (start_offset + start) & (PAGE_SIZE - 1);
5327
5328         while (len > 0) {
5329                 page = eb->pages[i];
5330
5331                 cur = min(len, (PAGE_SIZE - offset));
5332                 kaddr = page_address(page);
5333                 memcpy(dst, kaddr + offset, cur);
5334
5335                 dst += cur;
5336                 len -= cur;
5337                 offset = 0;
5338                 i++;
5339         }
5340 }
5341
5342 int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
5343                         unsigned long start,
5344                         unsigned long len)
5345 {
5346         size_t cur;
5347         size_t offset;
5348         struct page *page;
5349         char *kaddr;
5350         char __user *dst = (char __user *)dstv;
5351         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5352         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5353         int ret = 0;
5354
5355         WARN_ON(start > eb->len);
5356         WARN_ON(start + len > eb->start + eb->len);
5357
5358         offset = (start_offset + start) & (PAGE_SIZE - 1);
5359
5360         while (len > 0) {
5361                 page = eb->pages[i];
5362
5363                 cur = min(len, (PAGE_SIZE - offset));
5364                 kaddr = page_address(page);
5365                 if (copy_to_user(dst, kaddr + offset, cur)) {
5366                         ret = -EFAULT;
5367                         break;
5368                 }
5369
5370                 dst += cur;
5371                 len -= cur;
5372                 offset = 0;
5373                 i++;
5374         }
5375
5376         return ret;
5377 }
5378
5379 /*
5380  * return 0 if the item is found within a page.
5381  * return 1 if the item spans two pages.
5382  * return -EINVAL otherwise.
5383  */
5384 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
5385                                unsigned long min_len, char **map,
5386                                unsigned long *map_start,
5387                                unsigned long *map_len)
5388 {
5389         size_t offset = start & (PAGE_SIZE - 1);
5390         char *kaddr;
5391         struct page *p;
5392         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5393         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5394         unsigned long end_i = (start_offset + start + min_len - 1) >>
5395                 PAGE_SHIFT;
5396
5397         if (i != end_i)
5398                 return 1;
5399
5400         if (i == 0) {
5401                 offset = start_offset;
5402                 *map_start = 0;
5403         } else {
5404                 offset = 0;
5405                 *map_start = ((u64)i << PAGE_SHIFT) - start_offset;
5406         }
5407
5408         if (start + min_len > eb->len) {
5409                 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, "
5410                        "wanted %lu %lu\n",
5411                        eb->start, eb->len, start, min_len);
5412                 return -EINVAL;
5413         }
5414
5415         p = eb->pages[i];
5416         kaddr = page_address(p);
5417         *map = kaddr + offset;
5418         *map_len = PAGE_SIZE - offset;
5419         return 0;
5420 }
5421
5422 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
5423                           unsigned long start,
5424                           unsigned long len)
5425 {
5426         size_t cur;
5427         size_t offset;
5428         struct page *page;
5429         char *kaddr;
5430         char *ptr = (char *)ptrv;
5431         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5432         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5433         int ret = 0;
5434
5435         WARN_ON(start > eb->len);
5436         WARN_ON(start + len > eb->start + eb->len);
5437
5438         offset = (start_offset + start) & (PAGE_SIZE - 1);
5439
5440         while (len > 0) {
5441                 page = eb->pages[i];
5442
5443                 cur = min(len, (PAGE_SIZE - offset));
5444
5445                 kaddr = page_address(page);
5446                 ret = memcmp(ptr, kaddr + offset, cur);
5447                 if (ret)
5448                         break;
5449
5450                 ptr += cur;
5451                 len -= cur;
5452                 offset = 0;
5453                 i++;
5454         }
5455         return ret;
5456 }
5457
5458 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
5459                          unsigned long start, unsigned long len)
5460 {
5461         size_t cur;
5462         size_t offset;
5463         struct page *page;
5464         char *kaddr;
5465         char *src = (char *)srcv;
5466         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5467         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5468
5469         WARN_ON(start > eb->len);
5470         WARN_ON(start + len > eb->start + eb->len);
5471
5472         offset = (start_offset + start) & (PAGE_SIZE - 1);
5473
5474         while (len > 0) {
5475                 page = eb->pages[i];
5476                 WARN_ON(!PageUptodate(page));
5477
5478                 cur = min(len, PAGE_SIZE - offset);
5479                 kaddr = page_address(page);
5480                 memcpy(kaddr + offset, src, cur);
5481
5482                 src += cur;
5483                 len -= cur;
5484                 offset = 0;
5485                 i++;
5486         }
5487 }
5488
5489 void memset_extent_buffer(struct extent_buffer *eb, char c,
5490                           unsigned long start, unsigned long len)
5491 {
5492         size_t cur;
5493         size_t offset;
5494         struct page *page;
5495         char *kaddr;
5496         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5497         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5498
5499         WARN_ON(start > eb->len);
5500         WARN_ON(start + len > eb->start + eb->len);
5501
5502         offset = (start_offset + start) & (PAGE_SIZE - 1);
5503
5504         while (len > 0) {
5505                 page = eb->pages[i];
5506                 WARN_ON(!PageUptodate(page));
5507
5508                 cur = min(len, PAGE_SIZE - offset);
5509                 kaddr = page_address(page);
5510                 memset(kaddr + offset, c, cur);
5511
5512                 len -= cur;
5513                 offset = 0;
5514                 i++;
5515         }
5516 }
5517
5518 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
5519                         unsigned long dst_offset, unsigned long src_offset,
5520                         unsigned long len)
5521 {
5522         u64 dst_len = dst->len;
5523         size_t cur;
5524         size_t offset;
5525         struct page *page;
5526         char *kaddr;
5527         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5528         unsigned long i = (start_offset + dst_offset) >> PAGE_SHIFT;
5529
5530         WARN_ON(src->len != dst_len);
5531
5532         offset = (start_offset + dst_offset) &
5533                 (PAGE_SIZE - 1);
5534
5535         while (len > 0) {
5536                 page = dst->pages[i];
5537                 WARN_ON(!PageUptodate(page));
5538
5539                 cur = min(len, (unsigned long)(PAGE_SIZE - offset));
5540
5541                 kaddr = page_address(page);
5542                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
5543
5544                 src_offset += cur;
5545                 len -= cur;
5546                 offset = 0;
5547                 i++;
5548         }
5549 }
5550
5551 /*
5552  * The extent buffer bitmap operations are done with byte granularity because
5553  * bitmap items are not guaranteed to be aligned to a word and therefore a
5554  * single word in a bitmap may straddle two pages in the extent buffer.
5555  */
5556 #define BIT_BYTE(nr) ((nr) / BITS_PER_BYTE)
5557 #define BYTE_MASK ((1 << BITS_PER_BYTE) - 1)
5558 #define BITMAP_FIRST_BYTE_MASK(start) \
5559         ((BYTE_MASK << ((start) & (BITS_PER_BYTE - 1))) & BYTE_MASK)
5560 #define BITMAP_LAST_BYTE_MASK(nbits) \
5561         (BYTE_MASK >> (-(nbits) & (BITS_PER_BYTE - 1)))
5562
5563 /*
5564  * eb_bitmap_offset() - calculate the page and offset of the byte containing the
5565  * given bit number
5566  * @eb: the extent buffer
5567  * @start: offset of the bitmap item in the extent buffer
5568  * @nr: bit number
5569  * @page_index: return index of the page in the extent buffer that contains the
5570  * given bit number
5571  * @page_offset: return offset into the page given by page_index
5572  *
5573  * This helper hides the ugliness of finding the byte in an extent buffer which
5574  * contains a given bit.
5575  */
5576 static inline void eb_bitmap_offset(struct extent_buffer *eb,
5577                                     unsigned long start, unsigned long nr,
5578                                     unsigned long *page_index,
5579                                     size_t *page_offset)
5580 {
5581         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5582         size_t byte_offset = BIT_BYTE(nr);
5583         size_t offset;
5584
5585         /*
5586          * The byte we want is the offset of the extent buffer + the offset of
5587          * the bitmap item in the extent buffer + the offset of the byte in the
5588          * bitmap item.
5589          */
5590         offset = start_offset + start + byte_offset;
5591
5592         *page_index = offset >> PAGE_SHIFT;
5593         *page_offset = offset & (PAGE_SIZE - 1);
5594 }
5595
5596 /**
5597  * extent_buffer_test_bit - determine whether a bit in a bitmap item is set
5598  * @eb: the extent buffer
5599  * @start: offset of the bitmap item in the extent buffer
5600  * @nr: bit number to test
5601  */
5602 int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
5603                            unsigned long nr)
5604 {
5605         char *kaddr;
5606         struct page *page;
5607         unsigned long i;
5608         size_t offset;
5609
5610         eb_bitmap_offset(eb, start, nr, &i, &offset);
5611         page = eb->pages[i];
5612         WARN_ON(!PageUptodate(page));
5613         kaddr = page_address(page);
5614         return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1)));
5615 }
5616
5617 /**
5618  * extent_buffer_bitmap_set - set an area of a bitmap
5619  * @eb: the extent buffer
5620  * @start: offset of the bitmap item in the extent buffer
5621  * @pos: bit number of the first bit
5622  * @len: number of bits to set
5623  */
5624 void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
5625                               unsigned long pos, unsigned long len)
5626 {
5627         char *kaddr;
5628         struct page *page;
5629         unsigned long i;
5630         size_t offset;
5631         const unsigned int size = pos + len;
5632         int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5633         unsigned int mask_to_set = BITMAP_FIRST_BYTE_MASK(pos);
5634
5635         eb_bitmap_offset(eb, start, pos, &i, &offset);
5636         page = eb->pages[i];
5637         WARN_ON(!PageUptodate(page));
5638         kaddr = page_address(page);
5639
5640         while (len >= bits_to_set) {
5641                 kaddr[offset] |= mask_to_set;
5642                 len -= bits_to_set;
5643                 bits_to_set = BITS_PER_BYTE;
5644                 mask_to_set = ~0U;
5645                 if (++offset >= PAGE_SIZE && len > 0) {
5646                         offset = 0;
5647                         page = eb->pages[++i];
5648                         WARN_ON(!PageUptodate(page));
5649                         kaddr = page_address(page);
5650                 }
5651         }
5652         if (len) {
5653                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
5654                 kaddr[offset] |= mask_to_set;
5655         }
5656 }
5657
5658
5659 /**
5660  * extent_buffer_bitmap_clear - clear an area of a bitmap
5661  * @eb: the extent buffer
5662  * @start: offset of the bitmap item in the extent buffer
5663  * @pos: bit number of the first bit
5664  * @len: number of bits to clear
5665  */
5666 void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
5667                                 unsigned long pos, unsigned long len)
5668 {
5669         char *kaddr;
5670         struct page *page;
5671         unsigned long i;
5672         size_t offset;
5673         const unsigned int size = pos + len;
5674         int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5675         unsigned int mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos);
5676
5677         eb_bitmap_offset(eb, start, pos, &i, &offset);
5678         page = eb->pages[i];
5679         WARN_ON(!PageUptodate(page));
5680         kaddr = page_address(page);
5681
5682         while (len >= bits_to_clear) {
5683                 kaddr[offset] &= ~mask_to_clear;
5684                 len -= bits_to_clear;
5685                 bits_to_clear = BITS_PER_BYTE;
5686                 mask_to_clear = ~0U;
5687                 if (++offset >= PAGE_SIZE && len > 0) {
5688                         offset = 0;
5689                         page = eb->pages[++i];
5690                         WARN_ON(!PageUptodate(page));
5691                         kaddr = page_address(page);
5692                 }
5693         }
5694         if (len) {
5695                 mask_to_clear &= BITMAP_LAST_BYTE_MASK(size);
5696                 kaddr[offset] &= ~mask_to_clear;
5697         }
5698 }
5699
5700 static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
5701 {
5702         unsigned long distance = (src > dst) ? src - dst : dst - src;
5703         return distance < len;
5704 }
5705
5706 static void copy_pages(struct page *dst_page, struct page *src_page,
5707                        unsigned long dst_off, unsigned long src_off,
5708                        unsigned long len)
5709 {
5710         char *dst_kaddr = page_address(dst_page);
5711         char *src_kaddr;
5712         int must_memmove = 0;
5713
5714         if (dst_page != src_page) {
5715                 src_kaddr = page_address(src_page);
5716         } else {
5717                 src_kaddr = dst_kaddr;
5718                 if (areas_overlap(src_off, dst_off, len))
5719                         must_memmove = 1;
5720         }
5721
5722         if (must_memmove)
5723                 memmove(dst_kaddr + dst_off, src_kaddr + src_off, len);
5724         else
5725                 memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
5726 }
5727
5728 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5729                            unsigned long src_offset, unsigned long len)
5730 {
5731         size_t cur;
5732         size_t dst_off_in_page;
5733         size_t src_off_in_page;
5734         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5735         unsigned long dst_i;
5736         unsigned long src_i;
5737
5738         if (src_offset + len > dst->len) {
5739                 btrfs_err(dst->fs_info,
5740                         "memmove bogus src_offset %lu move "
5741                        "len %lu dst len %lu", src_offset, len, dst->len);
5742                 BUG_ON(1);
5743         }
5744         if (dst_offset + len > dst->len) {
5745                 btrfs_err(dst->fs_info,
5746                         "memmove bogus dst_offset %lu move "
5747                        "len %lu dst len %lu", dst_offset, len, dst->len);
5748                 BUG_ON(1);
5749         }
5750
5751         while (len > 0) {
5752                 dst_off_in_page = (start_offset + dst_offset) &
5753                         (PAGE_SIZE - 1);
5754                 src_off_in_page = (start_offset + src_offset) &
5755                         (PAGE_SIZE - 1);
5756
5757                 dst_i = (start_offset + dst_offset) >> PAGE_SHIFT;
5758                 src_i = (start_offset + src_offset) >> PAGE_SHIFT;
5759
5760                 cur = min(len, (unsigned long)(PAGE_SIZE -
5761                                                src_off_in_page));
5762                 cur = min_t(unsigned long, cur,
5763                         (unsigned long)(PAGE_SIZE - dst_off_in_page));
5764
5765                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
5766                            dst_off_in_page, src_off_in_page, cur);
5767
5768                 src_offset += cur;
5769                 dst_offset += cur;
5770                 len -= cur;
5771         }
5772 }
5773
5774 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5775                            unsigned long src_offset, unsigned long len)
5776 {
5777         size_t cur;
5778         size_t dst_off_in_page;
5779         size_t src_off_in_page;
5780         unsigned long dst_end = dst_offset + len - 1;
5781         unsigned long src_end = src_offset + len - 1;
5782         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5783         unsigned long dst_i;
5784         unsigned long src_i;
5785
5786         if (src_offset + len > dst->len) {
5787                 btrfs_err(dst->fs_info, "memmove bogus src_offset %lu move "
5788                        "len %lu len %lu", src_offset, len, dst->len);
5789                 BUG_ON(1);
5790         }
5791         if (dst_offset + len > dst->len) {
5792                 btrfs_err(dst->fs_info, "memmove bogus dst_offset %lu move "
5793                        "len %lu len %lu", dst_offset, len, dst->len);
5794                 BUG_ON(1);
5795         }
5796         if (dst_offset < src_offset) {
5797                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
5798                 return;
5799         }
5800         while (len > 0) {
5801                 dst_i = (start_offset + dst_end) >> PAGE_SHIFT;
5802                 src_i = (start_offset + src_end) >> PAGE_SHIFT;
5803
5804                 dst_off_in_page = (start_offset + dst_end) &
5805                         (PAGE_SIZE - 1);
5806                 src_off_in_page = (start_offset + src_end) &
5807                         (PAGE_SIZE - 1);
5808
5809                 cur = min_t(unsigned long, len, src_off_in_page + 1);
5810                 cur = min(cur, dst_off_in_page + 1);
5811                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
5812                            dst_off_in_page - cur + 1,
5813                            src_off_in_page - cur + 1, cur);
5814
5815                 dst_end -= cur;
5816                 src_end -= cur;
5817                 len -= cur;
5818         }
5819 }
5820
5821 int try_release_extent_buffer(struct page *page)
5822 {
5823         struct extent_buffer *eb;
5824
5825         /*
5826          * We need to make sure nobody is attaching this page to an eb right
5827          * now.
5828          */
5829         spin_lock(&page->mapping->private_lock);
5830         if (!PagePrivate(page)) {
5831                 spin_unlock(&page->mapping->private_lock);
5832                 return 1;
5833         }
5834
5835         eb = (struct extent_buffer *)page->private;
5836         BUG_ON(!eb);
5837
5838         /*
5839          * This is a little awful but should be ok, we need to make sure that
5840          * the eb doesn't disappear out from under us while we're looking at
5841          * this page.
5842          */
5843         spin_lock(&eb->refs_lock);
5844         if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
5845                 spin_unlock(&eb->refs_lock);
5846                 spin_unlock(&page->mapping->private_lock);
5847                 return 0;
5848         }
5849         spin_unlock(&page->mapping->private_lock);
5850
5851         /*
5852          * If tree ref isn't set then we know the ref on this eb is a real ref,
5853          * so just return, this page will likely be freed soon anyway.
5854          */
5855         if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
5856                 spin_unlock(&eb->refs_lock);
5857                 return 0;
5858         }
5859
5860         return release_extent_buffer(eb);
5861 }