fs/btrfs/extent

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This source file includes following definitions.
extent_state_in_tree
btrfs_leak_debug_add
btrfs_leak_debug_del
btrfs_leak_debug_check
__btrfs_debug_check_extent_io_range
add_extent_changeset
submit_one_bio
end_write_bio
flush_write_bio
extent_io_init
extent_io_exit
extent_io_tree_init
extent_io_tree_release
alloc_extent_state
free_extent_state
tree_insert
__etree_search
tree_search_for_insert
tree_search
merge_state
insert_state
split_state
next_state
clear_state_bit
alloc_extent_state_atomic
extent_io_tree_panic
__clear_extent_bit
wait_on_state
wait_extent_bit
set_state_bits
cache_state_if_flags
cache_state
__set_extent_bit
set_extent_bit
convert_extent_bit
set_record_extent_bits
set_extent_bits_nowait
clear_extent_bit
clear_record_extent_bits
lock_extent_bits
try_lock_extent
extent_range_clear_dirty_for_io
extent_range_redirty_for_io
find_first_extent_bit_state
find_first_extent_bit
find_first_clear_extent_bit
find_delalloc_range
__unlock_for_delalloc
lock_delalloc_pages
find_lock_delalloc_range
__process_pages_contig
extent_clear_unlock_delalloc
count_range_bits
set_state_failrec
get_state_failrec
test_range_bit
check_page_uptodate
free_io_failure
repair_io_failure
btrfs_repair_eb_io_failure
clean_io_failure
btrfs_free_io_failure_record
btrfs_get_io_failure_record
btrfs_check_repairable
btrfs_create_repair_bio
bio_readpage_error
end_extent_writepage
end_bio_extent_writepage
endio_readpage_release_extent
end_bio_extent_readpage
btrfs_io_bio_init
btrfs_bio_alloc
btrfs_bio_clone
btrfs_io_bio_alloc
btrfs_bio_clone_partial
submit_extent_page
attach_extent_buffer_page
set_page_extent_mapped
__get_extent_map
__do_readpage
contiguous_readpages
__extent_read_full_page
extent_read_full_page
update_nr_written
writepage_delalloc
__extent_writepage_io
__extent_writepage
wait_on_extent_buffer_writeback
end_extent_buffer_writeback
lock_extent_buffer_for_io
set_btree_ioerr
end_bio_extent_buffer_writepage
write_one_eb
btree_write_cache_pages
extent_write_cache_pages
extent_write_full_page
extent_write_locked_range
extent_writepages
extent_readpages
extent_invalidatepage
try_release_extent_state
try_release_extent_mapping
get_extent_skip_holes
emit_fiemap_extent
emit_last_fiemap_cache
extent_fiemap
__free_extent_buffer
extent_buffer_under_io
btrfs_release_extent_buffer_pages
btrfs_release_extent_buffer
__alloc_extent_buffer
btrfs_clone_extent_buffer
__alloc_dummy_extent_buffer
alloc_dummy_extent_buffer
check_buffer_tree_ref
mark_extent_buffer_accessed
find_extent_buffer
alloc_test_extent_buffer
alloc_extent_buffer
btrfs_release_extent_buffer_rcu
release_extent_buffer
free_extent_buffer
free_extent_buffer_stale
clear_extent_buffer_dirty
set_extent_buffer_dirty
clear_extent_buffer_uptodate
set_extent_buffer_uptodate
read_extent_buffer_pages
read_extent_buffer
read_extent_buffer_to_user
map_private_extent_buffer
memcmp_extent_buffer
write_extent_buffer_chunk_tree_uuid
write_extent_buffer_fsid
write_extent_buffer
memzero_extent_buffer
copy_extent_buffer_full
copy_extent_buffer
eb_bitmap_offset
extent_buffer_test_bit
extent_buffer_bitmap_set
extent_buffer_bitmap_clear
areas_overlap
copy_pages
memcpy_extent_buffer
memmove_extent_buffer
try_release_extent_buffer
   1 // SPDX-License-Identifier: GPL-2.0
   2 
   3 #include <linux/bitops.h>
   4 #include <linux/slab.h>
   5 #include <linux/bio.h>
   6 #include <linux/mm.h>
   7 #include <linux/pagemap.h>
   8 #include <linux/page-flags.h>
   9 #include <linux/spinlock.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/swap.h>
  12 #include <linux/writeback.h>
  13 #include <linux/pagevec.h>
  14 #include <linux/prefetch.h>
  15 #include <linux/cleancache.h>
  16 #include "extent_io.h"
  17 #include "extent_map.h"
  18 #include "ctree.h"
  19 #include "btrfs_inode.h"
  20 #include "volumes.h"
  21 #include "check-integrity.h"
  22 #include "locking.h"
  23 #include "rcu-string.h"
  24 #include "backref.h"
  25 #include "disk-io.h"
  26 
  27 static struct kmem_cache *extent_state_cache;
  28 static struct kmem_cache *extent_buffer_cache;
  29 static struct bio_set btrfs_bioset;
  30 
  31 static inline bool extent_state_in_tree(const struct extent_state *state)
  32 {
  33         return !RB_EMPTY_NODE(&state->rb_node);
  34 }
  35 
  36 #ifdef CONFIG_BTRFS_DEBUG
  37 static LIST_HEAD(buffers);
  38 static LIST_HEAD(states);
  39 
  40 static DEFINE_SPINLOCK(leak_lock);
  41 
  42 static inline
  43 void btrfs_leak_debug_add(struct list_head *new, struct list_head *head)
  44 {
  45         unsigned long flags;
  46 
  47         spin_lock_irqsave(&leak_lock, flags);
  48         list_add(new, head);
  49         spin_unlock_irqrestore(&leak_lock, flags);
  50 }
  51 
  52 static inline
  53 void btrfs_leak_debug_del(struct list_head *entry)
  54 {
  55         unsigned long flags;
  56 
  57         spin_lock_irqsave(&leak_lock, flags);
  58         list_del(entry);
  59         spin_unlock_irqrestore(&leak_lock, flags);
  60 }
  61 
  62 static inline
  63 void btrfs_leak_debug_check(void)
  64 {
  65         struct extent_state *state;
  66         struct extent_buffer *eb;
  67 
  68         while (!list_empty(&states)) {
  69                 state = list_entry(states.next, struct extent_state, leak_list);
  70                 pr_err("BTRFS: state leak: start %llu end %llu state %u in tree %d refs %d\n",
  71                        state->start, state->end, state->state,
  72                        extent_state_in_tree(state),
  73                        refcount_read(&state->refs));
  74                 list_del(&state->leak_list);
  75                 kmem_cache_free(extent_state_cache, state);
  76         }
  77 
  78         while (!list_empty(&buffers)) {
  79                 eb = list_entry(buffers.next, struct extent_buffer, leak_list);
  80                 pr_err("BTRFS: buffer leak start %llu len %lu refs %d bflags %lu\n",
  81                        eb->start, eb->len, atomic_read(&eb->refs), eb->bflags);
  82                 list_del(&eb->leak_list);
  83                 kmem_cache_free(extent_buffer_cache, eb);
  84         }
  85 }
  86 
  87 #define btrfs_debug_check_extent_io_range(tree, start, end)             \
  88         __btrfs_debug_check_extent_io_range(__func__, (tree), (start), (end))
  89 static inline void __btrfs_debug_check_extent_io_range(const char *caller,
  90                 struct extent_io_tree *tree, u64 start, u64 end)
  91 {
  92         struct inode *inode = tree->private_data;
  93         u64 isize;
  94 
  95         if (!inode || !is_data_inode(inode))
  96                 return;
  97 
  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(BTRFS_I(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 struct tree_entry {
 113         u64 start;
 114         u64 end;
 115         struct rb_node rb_node;
 116 };
 117 
 118 struct extent_page_data {
 119         struct bio *bio;
 120         struct extent_io_tree *tree;
 121         /* tells writepage not to lock the state bits for this range
 122          * it still does the unlocking
 123          */
 124         unsigned int extent_locked:1;
 125 
 126         /* tells the submit_bio code to use REQ_SYNC */
 127         unsigned int sync_io:1;
 128 };
 129 
 130 static int add_extent_changeset(struct extent_state *state, unsigned bits,
 131                                  struct extent_changeset *changeset,
 132                                  int set)
 133 {
 134         int ret;
 135 
 136         if (!changeset)
 137                 return 0;
 138         if (set && (state->state & bits) == bits)
 139                 return 0;
 140         if (!set && (state->state & bits) == 0)
 141                 return 0;
 142         changeset->bytes_changed += state->end - state->start + 1;
 143         ret = ulist_add(&changeset->range_changed, state->start, state->end,
 144                         GFP_ATOMIC);
 145         return ret;
 146 }
 147 
 148 static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
 149                                        unsigned long bio_flags)
 150 {
 151         blk_status_t ret = 0;
 152         struct extent_io_tree *tree = bio->bi_private;
 153 
 154         bio->bi_private = NULL;
 155 
 156         if (tree->ops)
 157                 ret = tree->ops->submit_bio_hook(tree->private_data, bio,
 158                                                  mirror_num, bio_flags);
 159         else
 160                 btrfsic_submit_bio(bio);
 161 
 162         return blk_status_to_errno(ret);
 163 }
 164 
 165 /* Cleanup unsubmitted bios */
 166 static void end_write_bio(struct extent_page_data *epd, int ret)
 167 {
 168         if (epd->bio) {
 169                 epd->bio->bi_status = errno_to_blk_status(ret);
 170                 bio_endio(epd->bio);
 171                 epd->bio = NULL;
 172         }
 173 }
 174 
 175 /*
 176  * Submit bio from extent page data via submit_one_bio
 177  *
 178  * Return 0 if everything is OK.
 179  * Return <0 for error.
 180  */
 181 static int __must_check flush_write_bio(struct extent_page_data *epd)
 182 {
 183         int ret = 0;
 184 
 185         if (epd->bio) {
 186                 ret = submit_one_bio(epd->bio, 0, 0);
 187                 /*
 188                  * Clean up of epd->bio is handled by its endio function.
 189                  * And endio is either triggered by successful bio execution
 190                  * or the error handler of submit bio hook.
 191                  * So at this point, no matter what happened, we don't need
 192                  * to clean up epd->bio.
 193                  */
 194                 epd->bio = NULL;
 195         }
 196         return ret;
 197 }
 198 
 199 int __init extent_io_init(void)
 200 {
 201         extent_state_cache = kmem_cache_create("btrfs_extent_state",
 202                         sizeof(struct extent_state), 0,
 203                         SLAB_MEM_SPREAD, NULL);
 204         if (!extent_state_cache)
 205                 return -ENOMEM;
 206 
 207         extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
 208                         sizeof(struct extent_buffer), 0,
 209                         SLAB_MEM_SPREAD, NULL);
 210         if (!extent_buffer_cache)
 211                 goto free_state_cache;
 212 
 213         if (bioset_init(&btrfs_bioset, BIO_POOL_SIZE,
 214                         offsetof(struct btrfs_io_bio, bio),
 215                         BIOSET_NEED_BVECS))
 216                 goto free_buffer_cache;
 217 
 218         if (bioset_integrity_create(&btrfs_bioset, BIO_POOL_SIZE))
 219                 goto free_bioset;
 220 
 221         return 0;
 222 
 223 free_bioset:
 224         bioset_exit(&btrfs_bioset);
 225 
 226 free_buffer_cache:
 227         kmem_cache_destroy(extent_buffer_cache);
 228         extent_buffer_cache = NULL;
 229 
 230 free_state_cache:
 231         kmem_cache_destroy(extent_state_cache);
 232         extent_state_cache = NULL;
 233         return -ENOMEM;
 234 }
 235 
 236 void __cold extent_io_exit(void)
 237 {
 238         btrfs_leak_debug_check();
 239 
 240         /*
 241          * Make sure all delayed rcu free are flushed before we
 242          * destroy caches.
 243          */
 244         rcu_barrier();
 245         kmem_cache_destroy(extent_state_cache);
 246         kmem_cache_destroy(extent_buffer_cache);
 247         bioset_exit(&btrfs_bioset);
 248 }
 249 
 250 void extent_io_tree_init(struct btrfs_fs_info *fs_info,
 251                          struct extent_io_tree *tree, unsigned int owner,
 252                          void *private_data)
 253 {
 254         tree->fs_info = fs_info;
 255         tree->state = RB_ROOT;
 256         tree->ops = NULL;
 257         tree->dirty_bytes = 0;
 258         spin_lock_init(&tree->lock);
 259         tree->private_data = private_data;
 260         tree->owner = owner;
 261 }
 262 
 263 void extent_io_tree_release(struct extent_io_tree *tree)
 264 {
 265         spin_lock(&tree->lock);
 266         /*
 267          * Do a single barrier for the waitqueue_active check here, the state
 268          * of the waitqueue should not change once extent_io_tree_release is
 269          * called.
 270          */
 271         smp_mb();
 272         while (!RB_EMPTY_ROOT(&tree->state)) {
 273                 struct rb_node *node;
 274                 struct extent_state *state;
 275 
 276                 node = rb_first(&tree->state);
 277                 state = rb_entry(node, struct extent_state, rb_node);
 278                 rb_erase(&state->rb_node, &tree->state);
 279                 RB_CLEAR_NODE(&state->rb_node);
 280                 /*
 281                  * btree io trees aren't supposed to have tasks waiting for
 282                  * changes in the flags of extent states ever.
 283                  */
 284                 ASSERT(!waitqueue_active(&state->wq));
 285                 free_extent_state(state);
 286 
 287                 cond_resched_lock(&tree->lock);
 288         }
 289         spin_unlock(&tree->lock);
 290 }
 291 
 292 static struct extent_state *alloc_extent_state(gfp_t mask)
 293 {
 294         struct extent_state *state;
 295 
 296         /*
 297          * The given mask might be not appropriate for the slab allocator,
 298          * drop the unsupported bits
 299          */
 300         mask &= ~(__GFP_DMA32|__GFP_HIGHMEM);
 301         state = kmem_cache_alloc(extent_state_cache, mask);
 302         if (!state)
 303                 return state;
 304         state->state = 0;
 305         state->failrec = NULL;
 306         RB_CLEAR_NODE(&state->rb_node);
 307         btrfs_leak_debug_add(&state->leak_list, &states);
 308         refcount_set(&state->refs, 1);
 309         init_waitqueue_head(&state->wq);
 310         trace_alloc_extent_state(state, mask, _RET_IP_);
 311         return state;
 312 }
 313 
 314 void free_extent_state(struct extent_state *state)
 315 {
 316         if (!state)
 317                 return;
 318         if (refcount_dec_and_test(&state->refs)) {
 319                 WARN_ON(extent_state_in_tree(state));
 320                 btrfs_leak_debug_del(&state->leak_list);
 321                 trace_free_extent_state(state, _RET_IP_);
 322                 kmem_cache_free(extent_state_cache, state);
 323         }
 324 }
 325 
 326 static struct rb_node *tree_insert(struct rb_root *root,
 327                                    struct rb_node *search_start,
 328                                    u64 offset,
 329                                    struct rb_node *node,
 330                                    struct rb_node ***p_in,
 331                                    struct rb_node **parent_in)
 332 {
 333         struct rb_node **p;
 334         struct rb_node *parent = NULL;
 335         struct tree_entry *entry;
 336 
 337         if (p_in && parent_in) {
 338                 p = *p_in;
 339                 parent = *parent_in;
 340                 goto do_insert;
 341         }
 342 
 343         p = search_start ? &search_start : &root->rb_node;
 344         while (*p) {
 345                 parent = *p;
 346                 entry = rb_entry(parent, struct tree_entry, rb_node);
 347 
 348                 if (offset < entry->start)
 349                         p = &(*p)->rb_left;
 350                 else if (offset > entry->end)
 351                         p = &(*p)->rb_right;
 352                 else
 353                         return parent;
 354         }
 355 
 356 do_insert:
 357         rb_link_node(node, parent, p);
 358         rb_insert_color(node, root);
 359         return NULL;
 360 }
 361 
 362 /**
 363  * __etree_search - searche @tree for an entry that contains @offset. Such
 364  * entry would have entry->start <= offset && entry->end >= offset.
 365  *
 366  * @tree - the tree to search
 367  * @offset - offset that should fall within an entry in @tree
 368  * @next_ret - pointer to the first entry whose range ends after @offset
 369  * @prev - pointer to the first entry whose range begins before @offset
 370  * @p_ret - pointer where new node should be anchored (used when inserting an
 371  *          entry in the tree)
 372  * @parent_ret - points to entry which would have been the parent of the entry,
 373  *               containing @offset
 374  *
 375  * This function returns a pointer to the entry that contains @offset byte
 376  * address. If no such entry exists, then NULL is returned and the other
 377  * pointer arguments to the function are filled, otherwise the found entry is
 378  * returned and other pointers are left untouched.
 379  */
 380 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 381                                       struct rb_node **next_ret,
 382                                       struct rb_node **prev_ret,
 383                                       struct rb_node ***p_ret,
 384                                       struct rb_node **parent_ret)
 385 {
 386         struct rb_root *root = &tree->state;
 387         struct rb_node **n = &root->rb_node;
 388         struct rb_node *prev = NULL;
 389         struct rb_node *orig_prev = NULL;
 390         struct tree_entry *entry;
 391         struct tree_entry *prev_entry = NULL;
 392 
 393         while (*n) {
 394                 prev = *n;
 395                 entry = rb_entry(prev, struct tree_entry, rb_node);
 396                 prev_entry = entry;
 397 
 398                 if (offset < entry->start)
 399                         n = &(*n)->rb_left;
 400                 else if (offset > entry->end)
 401                         n = &(*n)->rb_right;
 402                 else
 403                         return *n;
 404         }
 405 
 406         if (p_ret)
 407                 *p_ret = n;
 408         if (parent_ret)
 409                 *parent_ret = prev;
 410 
 411         if (next_ret) {
 412                 orig_prev = prev;
 413                 while (prev && offset > prev_entry->end) {
 414                         prev = rb_next(prev);
 415                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 416                 }
 417                 *next_ret = prev;
 418                 prev = orig_prev;
 419         }
 420 
 421         if (prev_ret) {
 422                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 423                 while (prev && offset < prev_entry->start) {
 424                         prev = rb_prev(prev);
 425                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
 426                 }
 427                 *prev_ret = prev;
 428         }
 429         return NULL;
 430 }
 431 
 432 static inline struct rb_node *
 433 tree_search_for_insert(struct extent_io_tree *tree,
 434                        u64 offset,
 435                        struct rb_node ***p_ret,
 436                        struct rb_node **parent_ret)
 437 {
 438         struct rb_node *next= NULL;
 439         struct rb_node *ret;
 440 
 441         ret = __etree_search(tree, offset, &next, NULL, p_ret, parent_ret);
 442         if (!ret)
 443                 return next;
 444         return ret;
 445 }
 446 
 447 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 448                                           u64 offset)
 449 {
 450         return tree_search_for_insert(tree, offset, NULL, NULL);
 451 }
 452 
 453 /*
 454  * utility function to look for merge candidates inside a given range.
 455  * Any extents with matching state are merged together into a single
 456  * extent in the tree.  Extents with EXTENT_IO in their state field
 457  * are not merged because the end_io handlers need to be able to do
 458  * operations on them without sleeping (or doing allocations/splits).
 459  *
 460  * This should be called with the tree lock held.
 461  */
 462 static void merge_state(struct extent_io_tree *tree,
 463                         struct extent_state *state)
 464 {
 465         struct extent_state *other;
 466         struct rb_node *other_node;
 467 
 468         if (state->state & (EXTENT_LOCKED | EXTENT_BOUNDARY))
 469                 return;
 470 
 471         other_node = rb_prev(&state->rb_node);
 472         if (other_node) {
 473                 other = rb_entry(other_node, struct extent_state, rb_node);
 474                 if (other->end == state->start - 1 &&
 475                     other->state == state->state) {
 476                         if (tree->private_data &&
 477                             is_data_inode(tree->private_data))
 478                                 btrfs_merge_delalloc_extent(tree->private_data,
 479                                                             state, other);
 480                         state->start = other->start;
 481                         rb_erase(&other->rb_node, &tree->state);
 482                         RB_CLEAR_NODE(&other->rb_node);
 483                         free_extent_state(other);
 484                 }
 485         }
 486         other_node = rb_next(&state->rb_node);
 487         if (other_node) {
 488                 other = rb_entry(other_node, struct extent_state, rb_node);
 489                 if (other->start == state->end + 1 &&
 490                     other->state == state->state) {
 491                         if (tree->private_data &&
 492                             is_data_inode(tree->private_data))
 493                                 btrfs_merge_delalloc_extent(tree->private_data,
 494                                                             state, other);
 495                         state->end = other->end;
 496                         rb_erase(&other->rb_node, &tree->state);
 497                         RB_CLEAR_NODE(&other->rb_node);
 498                         free_extent_state(other);
 499                 }
 500         }
 501 }
 502 
 503 static void set_state_bits(struct extent_io_tree *tree,
 504                            struct extent_state *state, unsigned *bits,
 505                            struct extent_changeset *changeset);
 506 
 507 /*
 508  * insert an extent_state struct into the tree.  'bits' are set on the
 509  * struct before it is inserted.
 510  *
 511  * This may return -EEXIST if the extent is already there, in which case the
 512  * state struct is freed.
 513  *
 514  * The tree lock is not taken internally.  This is a utility function and
 515  * probably isn't what you want to call (see set/clear_extent_bit).
 516  */
 517 static int insert_state(struct extent_io_tree *tree,
 518                         struct extent_state *state, u64 start, u64 end,
 519                         struct rb_node ***p,
 520                         struct rb_node **parent,
 521                         unsigned *bits, struct extent_changeset *changeset)
 522 {
 523         struct rb_node *node;
 524 
 525         if (end < start) {
 526                 btrfs_err(tree->fs_info,
 527                         "insert state: end < start %llu %llu", end, start);
 528                 WARN_ON(1);
 529         }
 530         state->start = start;
 531         state->end = end;
 532 
 533         set_state_bits(tree, state, bits, changeset);
 534 
 535         node = tree_insert(&tree->state, NULL, end, &state->rb_node, p, parent);
 536         if (node) {
 537                 struct extent_state *found;
 538                 found = rb_entry(node, struct extent_state, rb_node);
 539                 btrfs_err(tree->fs_info,
 540                        "found node %llu %llu on insert of %llu %llu",
 541                        found->start, found->end, start, end);
 542                 return -EEXIST;
 543         }
 544         merge_state(tree, state);
 545         return 0;
 546 }
 547 
 548 /*
 549  * split a given extent state struct in two, inserting the preallocated
 550  * struct 'prealloc' as the newly created second half.  'split' indicates an
 551  * offset inside 'orig' where it should be split.
 552  *
 553  * Before calling,
 554  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
 555  * are two extent state structs in the tree:
 556  * prealloc: [orig->start, split - 1]
 557  * orig: [ split, orig->end ]
 558  *
 559  * The tree locks are not taken by this function. They need to be held
 560  * by the caller.
 561  */
 562 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 563                        struct extent_state *prealloc, u64 split)
 564 {
 565         struct rb_node *node;
 566 
 567         if (tree->private_data && is_data_inode(tree->private_data))
 568                 btrfs_split_delalloc_extent(tree->private_data, orig, split);
 569 
 570         prealloc->start = orig->start;
 571         prealloc->end = split - 1;
 572         prealloc->state = orig->state;
 573         orig->start = split;
 574 
 575         node = tree_insert(&tree->state, &orig->rb_node, prealloc->end,
 576                            &prealloc->rb_node, NULL, NULL);
 577         if (node) {
 578                 free_extent_state(prealloc);
 579                 return -EEXIST;
 580         }
 581         return 0;
 582 }
 583 
 584 static struct extent_state *next_state(struct extent_state *state)
 585 {
 586         struct rb_node *next = rb_next(&state->rb_node);
 587         if (next)
 588                 return rb_entry(next, struct extent_state, rb_node);
 589         else
 590                 return NULL;
 591 }
 592 
 593 /*
 594  * utility function to clear some bits in an extent state struct.
 595  * it will optionally wake up anyone waiting on this state (wake == 1).
 596  *
 597  * If no bits are set on the state struct after clearing things, the
 598  * struct is freed and removed from the tree
 599  */
 600 static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
 601                                             struct extent_state *state,
 602                                             unsigned *bits, int wake,
 603                                             struct extent_changeset *changeset)
 604 {
 605         struct extent_state *next;
 606         unsigned bits_to_clear = *bits & ~EXTENT_CTLBITS;
 607         int ret;
 608 
 609         if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
 610                 u64 range = state->end - state->start + 1;
 611                 WARN_ON(range > tree->dirty_bytes);
 612                 tree->dirty_bytes -= range;
 613         }
 614 
 615         if (tree->private_data && is_data_inode(tree->private_data))
 616                 btrfs_clear_delalloc_extent(tree->private_data, state, bits);
 617 
 618         ret = add_extent_changeset(state, bits_to_clear, changeset, 0);
 619         BUG_ON(ret < 0);
 620         state->state &= ~bits_to_clear;
 621         if (wake)
 622                 wake_up(&state->wq);
 623         if (state->state == 0) {
 624                 next = next_state(state);
 625                 if (extent_state_in_tree(state)) {
 626                         rb_erase(&state->rb_node, &tree->state);
 627                         RB_CLEAR_NODE(&state->rb_node);
 628                         free_extent_state(state);
 629                 } else {
 630                         WARN_ON(1);
 631                 }
 632         } else {
 633                 merge_state(tree, state);
 634                 next = next_state(state);
 635         }
 636         return next;
 637 }
 638 
 639 static struct extent_state *
 640 alloc_extent_state_atomic(struct extent_state *prealloc)
 641 {
 642         if (!prealloc)
 643                 prealloc = alloc_extent_state(GFP_ATOMIC);
 644 
 645         return prealloc;
 646 }
 647 
 648 static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
 649 {
 650         struct inode *inode = tree->private_data;
 651 
 652         btrfs_panic(btrfs_sb(inode->i_sb), err,
 653         "locking error: extent tree was modified by another thread while locked");
 654 }
 655 
 656 /*
 657  * clear some bits on a range in the tree.  This may require splitting
 658  * or inserting elements in the tree, so the gfp mask is used to
 659  * indicate which allocations or sleeping are allowed.
 660  *
 661  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
 662  * the given range from the tree regardless of state (ie for truncate).
 663  *
 664  * the range [start, end] is inclusive.
 665  *
 666  * This takes the tree lock, and returns 0 on success and < 0 on error.
 667  */
 668 int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 669                               unsigned bits, int wake, int delete,
 670                               struct extent_state **cached_state,
 671                               gfp_t mask, struct extent_changeset *changeset)
 672 {
 673         struct extent_state *state;
 674         struct extent_state *cached;
 675         struct extent_state *prealloc = NULL;
 676         struct rb_node *node;
 677         u64 last_end;
 678         int err;
 679         int clear = 0;
 680 
 681         btrfs_debug_check_extent_io_range(tree, start, end);
 682         trace_btrfs_clear_extent_bit(tree, start, end - start + 1, bits);
 683 
 684         if (bits & EXTENT_DELALLOC)
 685                 bits |= EXTENT_NORESERVE;
 686 
 687         if (delete)
 688                 bits |= ~EXTENT_CTLBITS;
 689 
 690         if (bits & (EXTENT_LOCKED | EXTENT_BOUNDARY))
 691                 clear = 1;
 692 again:
 693         if (!prealloc && gfpflags_allow_blocking(mask)) {
 694                 /*
 695                  * Don't care for allocation failure here because we might end
 696                  * up not needing the pre-allocated extent state at all, which
 697                  * is the case if we only have in the tree extent states that
 698                  * cover our input range and don't cover too any other range.
 699                  * If we end up needing a new extent state we allocate it later.
 700                  */
 701                 prealloc = alloc_extent_state(mask);
 702         }
 703 
 704         spin_lock(&tree->lock);
 705         if (cached_state) {
 706                 cached = *cached_state;
 707 
 708                 if (clear) {
 709                         *cached_state = NULL;
 710                         cached_state = NULL;
 711                 }
 712 
 713                 if (cached && extent_state_in_tree(cached) &&
 714                     cached->start <= start && cached->end > start) {
 715                         if (clear)
 716                                 refcount_dec(&cached->refs);
 717                         state = cached;
 718                         goto hit_next;
 719                 }
 720                 if (clear)
 721                         free_extent_state(cached);
 722         }
 723         /*
 724          * this search will find the extents that end after
 725          * our range starts
 726          */
 727         node = tree_search(tree, start);
 728         if (!node)
 729                 goto out;
 730         state = rb_entry(node, struct extent_state, rb_node);
 731 hit_next:
 732         if (state->start > end)
 733                 goto out;
 734         WARN_ON(state->end < start);
 735         last_end = state->end;
 736 
 737         /* the state doesn't have the wanted bits, go ahead */
 738         if (!(state->state & bits)) {
 739                 state = next_state(state);
 740                 goto next;
 741         }
 742 
 743         /*
 744          *     | ---- desired range ---- |
 745          *  | state | or
 746          *  | ------------- state -------------- |
 747          *
 748          * We need to split the extent we found, and may flip
 749          * bits on second half.
 750          *
 751          * If the extent we found extends past our range, we
 752          * just split and search again.  It'll get split again
 753          * the next time though.
 754          *
 755          * If the extent we found is inside our range, we clear
 756          * the desired bit on it.
 757          */
 758 
 759         if (state->start < start) {
 760                 prealloc = alloc_extent_state_atomic(prealloc);
 761                 BUG_ON(!prealloc);
 762                 err = split_state(tree, state, prealloc, start);
 763                 if (err)
 764                         extent_io_tree_panic(tree, err);
 765 
 766                 prealloc = NULL;
 767                 if (err)
 768                         goto out;
 769                 if (state->end <= end) {
 770                         state = clear_state_bit(tree, state, &bits, wake,
 771                                                 changeset);
 772                         goto next;
 773                 }
 774                 goto search_again;
 775         }
 776         /*
 777          * | ---- desired range ---- |
 778          *                        | state |
 779          * We need to split the extent, and clear the bit
 780          * on the first half
 781          */
 782         if (state->start <= end && state->end > end) {
 783                 prealloc = alloc_extent_state_atomic(prealloc);
 784                 BUG_ON(!prealloc);
 785                 err = split_state(tree, state, prealloc, end + 1);
 786                 if (err)
 787                         extent_io_tree_panic(tree, err);
 788 
 789                 if (wake)
 790                         wake_up(&state->wq);
 791 
 792                 clear_state_bit(tree, prealloc, &bits, wake, changeset);
 793 
 794                 prealloc = NULL;
 795                 goto out;
 796         }
 797 
 798         state = clear_state_bit(tree, state, &bits, wake, changeset);
 799 next:
 800         if (last_end == (u64)-1)
 801                 goto out;
 802         start = last_end + 1;
 803         if (start <= end && state && !need_resched())
 804                 goto hit_next;
 805 
 806 search_again:
 807         if (start > end)
 808                 goto out;
 809         spin_unlock(&tree->lock);
 810         if (gfpflags_allow_blocking(mask))
 811                 cond_resched();
 812         goto again;
 813 
 814 out:
 815         spin_unlock(&tree->lock);
 816         if (prealloc)
 817                 free_extent_state(prealloc);
 818 
 819         return 0;
 820 
 821 }
 822 
 823 static void wait_on_state(struct extent_io_tree *tree,
 824                           struct extent_state *state)
 825                 __releases(tree->lock)
 826                 __acquires(tree->lock)
 827 {
 828         DEFINE_WAIT(wait);
 829         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
 830         spin_unlock(&tree->lock);
 831         schedule();
 832         spin_lock(&tree->lock);
 833         finish_wait(&state->wq, &wait);
 834 }
 835 
 836 /*
 837  * waits for one or more bits to clear on a range in the state tree.
 838  * The range [start, end] is inclusive.
 839  * The tree lock is taken by this function
 840  */
 841 static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 842                             unsigned long bits)
 843 {
 844         struct extent_state *state;
 845         struct rb_node *node;
 846 
 847         btrfs_debug_check_extent_io_range(tree, start, end);
 848 
 849         spin_lock(&tree->lock);
 850 again:
 851         while (1) {
 852                 /*
 853                  * this search will find all the extents that end after
 854                  * our range starts
 855                  */
 856                 node = tree_search(tree, start);
 857 process_node:
 858                 if (!node)
 859                         break;
 860 
 861                 state = rb_entry(node, struct extent_state, rb_node);
 862 
 863                 if (state->start > end)
 864                         goto out;
 865 
 866                 if (state->state & bits) {
 867                         start = state->start;
 868                         refcount_inc(&state->refs);
 869                         wait_on_state(tree, state);
 870                         free_extent_state(state);
 871                         goto again;
 872                 }
 873                 start = state->end + 1;
 874 
 875                 if (start > end)
 876                         break;
 877 
 878                 if (!cond_resched_lock(&tree->lock)) {
 879                         node = rb_next(node);
 880                         goto process_node;
 881                 }
 882         }
 883 out:
 884         spin_unlock(&tree->lock);
 885 }
 886 
 887 static void set_state_bits(struct extent_io_tree *tree,
 888                            struct extent_state *state,
 889                            unsigned *bits, struct extent_changeset *changeset)
 890 {
 891         unsigned bits_to_set = *bits & ~EXTENT_CTLBITS;
 892         int ret;
 893 
 894         if (tree->private_data && is_data_inode(tree->private_data))
 895                 btrfs_set_delalloc_extent(tree->private_data, state, bits);
 896 
 897         if ((bits_to_set & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
 898                 u64 range = state->end - state->start + 1;
 899                 tree->dirty_bytes += range;
 900         }
 901         ret = add_extent_changeset(state, bits_to_set, changeset, 1);
 902         BUG_ON(ret < 0);
 903         state->state |= bits_to_set;
 904 }
 905 
 906 static void cache_state_if_flags(struct extent_state *state,
 907                                  struct extent_state **cached_ptr,
 908                                  unsigned flags)
 909 {
 910         if (cached_ptr && !(*cached_ptr)) {
 911                 if (!flags || (state->state & flags)) {
 912                         *cached_ptr = state;
 913                         refcount_inc(&state->refs);
 914                 }
 915         }
 916 }
 917 
 918 static void cache_state(struct extent_state *state,
 919                         struct extent_state **cached_ptr)
 920 {
 921         return cache_state_if_flags(state, cached_ptr,
 922                                     EXTENT_LOCKED | EXTENT_BOUNDARY);
 923 }
 924 
 925 /*
 926  * set some bits on a range in the tree.  This may require allocations or
 927  * sleeping, so the gfp mask is used to indicate what is allowed.
 928  *
 929  * If any of the exclusive bits are set, this will fail with -EEXIST if some
 930  * part of the range already has the desired bits set.  The start of the
 931  * existing range is returned in failed_start in this case.
 932  *
 933  * [start, end] is inclusive This takes the tree lock.
 934  */
 935 
 936 static int __must_check
 937 __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 938                  unsigned bits, unsigned exclusive_bits,
 939                  u64 *failed_start, struct extent_state **cached_state,
 940                  gfp_t mask, struct extent_changeset *changeset)
 941 {
 942         struct extent_state *state;
 943         struct extent_state *prealloc = NULL;
 944         struct rb_node *node;
 945         struct rb_node **p;
 946         struct rb_node *parent;
 947         int err = 0;
 948         u64 last_start;
 949         u64 last_end;
 950 
 951         btrfs_debug_check_extent_io_range(tree, start, end);
 952         trace_btrfs_set_extent_bit(tree, start, end - start + 1, bits);
 953 
 954 again:
 955         if (!prealloc && gfpflags_allow_blocking(mask)) {
 956                 /*
 957                  * Don't care for allocation failure here because we might end
 958                  * up not needing the pre-allocated extent state at all, which
 959                  * is the case if we only have in the tree extent states that
 960                  * cover our input range and don't cover too any other range.
 961                  * If we end up needing a new extent state we allocate it later.
 962                  */
 963                 prealloc = alloc_extent_state(mask);
 964         }
 965 
 966         spin_lock(&tree->lock);
 967         if (cached_state && *cached_state) {
 968                 state = *cached_state;
 969                 if (state->start <= start && state->end > start &&
 970                     extent_state_in_tree(state)) {
 971                         node = &state->rb_node;
 972                         goto hit_next;
 973                 }
 974         }
 975         /*
 976          * this search will find all the extents that end after
 977          * our range starts.
 978          */
 979         node = tree_search_for_insert(tree, start, &p, &parent);
 980         if (!node) {
 981                 prealloc = alloc_extent_state_atomic(prealloc);
 982                 BUG_ON(!prealloc);
 983                 err = insert_state(tree, prealloc, start, end,
 984                                    &p, &parent, &bits, changeset);
 985                 if (err)
 986                         extent_io_tree_panic(tree, err);
 987 
 988                 cache_state(prealloc, cached_state);
 989                 prealloc = NULL;
 990                 goto out;
 991         }
 992         state = rb_entry(node, struct extent_state, rb_node);
 993 hit_next:
 994         last_start = state->start;
 995         last_end = state->end;
 996 
 997         /*
 998          * | ---- desired range ---- |
 999          * | state |
1000          *
1001          * Just lock what we found and keep going
1002          */
1003         if (state->start == start && state->end <= end) {
1004                 if (state->state & exclusive_bits) {
1005                         *failed_start = state->start;
1006                         err = -EEXIST;
1007                         goto out;
1008                 }
1009 
1010                 set_state_bits(tree, state, &bits, changeset);
1011                 cache_state(state, cached_state);
1012                 merge_state(tree, state);
1013                 if (last_end == (u64)-1)
1014                         goto out;
1015                 start = last_end + 1;
1016                 state = next_state(state);
1017                 if (start < end && state && state->start == start &&
1018                     !need_resched())
1019                         goto hit_next;
1020                 goto search_again;
1021         }
1022 
1023         /*
1024          *     | ---- desired range ---- |
1025          * | state |
1026          *   or
1027          * | ------------- state -------------- |
1028          *
1029          * We need to split the extent we found, and may flip bits on
1030          * second half.
1031          *
1032          * If the extent we found extends past our
1033          * range, we just split and search again.  It'll get split
1034          * again the next time though.
1035          *
1036          * If the extent we found is inside our range, we set the
1037          * desired bit on it.
1038          */
1039         if (state->start < start) {
1040                 if (state->state & exclusive_bits) {
1041                         *failed_start = start;
1042                         err = -EEXIST;
1043                         goto out;
1044                 }
1045 
1046                 prealloc = alloc_extent_state_atomic(prealloc);
1047                 BUG_ON(!prealloc);
1048                 err = split_state(tree, state, prealloc, start);
1049                 if (err)
1050                         extent_io_tree_panic(tree, err);
1051 
1052                 prealloc = NULL;
1053                 if (err)
1054                         goto out;
1055                 if (state->end <= end) {
1056                         set_state_bits(tree, state, &bits, changeset);
1057                         cache_state(state, cached_state);
1058                         merge_state(tree, state);
1059                         if (last_end == (u64)-1)
1060                                 goto out;
1061                         start = last_end + 1;
1062                         state = next_state(state);
1063                         if (start < end && state && state->start == start &&
1064                             !need_resched())
1065                                 goto hit_next;
1066                 }
1067                 goto search_again;
1068         }
1069         /*
1070          * | ---- desired range ---- |
1071          *     | state | or               | state |
1072          *
1073          * There's a hole, we need to insert something in it and
1074          * ignore the extent we found.
1075          */
1076         if (state->start > start) {
1077                 u64 this_end;
1078                 if (end < last_start)
1079                         this_end = end;
1080                 else
1081                         this_end = last_start - 1;
1082 
1083                 prealloc = alloc_extent_state_atomic(prealloc);
1084                 BUG_ON(!prealloc);
1085 
1086                 /*
1087                  * Avoid to free 'prealloc' if it can be merged with
1088                  * the later extent.
1089                  */
1090                 err = insert_state(tree, prealloc, start, this_end,
1091                                    NULL, NULL, &bits, changeset);
1092                 if (err)
1093                         extent_io_tree_panic(tree, err);
1094 
1095                 cache_state(prealloc, cached_state);
1096                 prealloc = NULL;
1097                 start = this_end + 1;
1098                 goto search_again;
1099         }
1100         /*
1101          * | ---- desired range ---- |
1102          *                        | state |
1103          * We need to split the extent, and set the bit
1104          * on the first half
1105          */
1106         if (state->start <= end && state->end > end) {
1107                 if (state->state & exclusive_bits) {
1108                         *failed_start = start;
1109                         err = -EEXIST;
1110                         goto out;
1111                 }
1112 
1113                 prealloc = alloc_extent_state_atomic(prealloc);
1114                 BUG_ON(!prealloc);
1115                 err = split_state(tree, state, prealloc, end + 1);
1116                 if (err)
1117                         extent_io_tree_panic(tree, err);
1118 
1119                 set_state_bits(tree, prealloc, &bits, changeset);
1120                 cache_state(prealloc, cached_state);
1121                 merge_state(tree, prealloc);
1122                 prealloc = NULL;
1123                 goto out;
1124         }
1125 
1126 search_again:
1127         if (start > end)
1128                 goto out;
1129         spin_unlock(&tree->lock);
1130         if (gfpflags_allow_blocking(mask))
1131                 cond_resched();
1132         goto again;
1133 
1134 out:
1135         spin_unlock(&tree->lock);
1136         if (prealloc)
1137                 free_extent_state(prealloc);
1138 
1139         return err;
1140 
1141 }
1142 
1143 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1144                    unsigned bits, u64 * failed_start,
1145                    struct extent_state **cached_state, gfp_t mask)
1146 {
1147         return __set_extent_bit(tree, start, end, bits, 0, failed_start,
1148                                 cached_state, mask, NULL);
1149 }
1150 
1151 
1152 /**
1153  * convert_extent_bit - convert all bits in a given range from one bit to
1154  *                      another
1155  * @tree:       the io tree to search
1156  * @start:      the start offset in bytes
1157  * @end:        the end offset in bytes (inclusive)
1158  * @bits:       the bits to set in this range
1159  * @clear_bits: the bits to clear in this range
1160  * @cached_state:       state that we're going to cache
1161  *
1162  * This will go through and set bits for the given range.  If any states exist
1163  * already in this range they are set with the given bit and cleared of the
1164  * clear_bits.  This is only meant to be used by things that are mergeable, ie
1165  * converting from say DELALLOC to DIRTY.  This is not meant to be used with
1166  * boundary bits like LOCK.
1167  *
1168  * All allocations are done with GFP_NOFS.
1169  */
1170 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1171                        unsigned bits, unsigned clear_bits,
1172                        struct extent_state **cached_state)
1173 {
1174         struct extent_state *state;
1175         struct extent_state *prealloc = NULL;
1176         struct rb_node *node;
1177         struct rb_node **p;
1178         struct rb_node *parent;
1179         int err = 0;
1180         u64 last_start;
1181         u64 last_end;
1182         bool first_iteration = true;
1183 
1184         btrfs_debug_check_extent_io_range(tree, start, end);
1185         trace_btrfs_convert_extent_bit(tree, start, end - start + 1, bits,
1186                                        clear_bits);
1187 
1188 again:
1189         if (!prealloc) {
1190                 /*
1191                  * Best effort, don't worry if extent state allocation fails
1192                  * here for the first iteration. We might have a cached state
1193                  * that matches exactly the target range, in which case no
1194                  * extent state allocations are needed. We'll only know this
1195                  * after locking the tree.
1196                  */
1197                 prealloc = alloc_extent_state(GFP_NOFS);
1198                 if (!prealloc && !first_iteration)
1199                         return -ENOMEM;
1200         }
1201 
1202         spin_lock(&tree->lock);
1203         if (cached_state && *cached_state) {
1204                 state = *cached_state;
1205                 if (state->start <= start && state->end > start &&
1206                     extent_state_in_tree(state)) {
1207                         node = &state->rb_node;
1208                         goto hit_next;
1209                 }
1210         }
1211 
1212         /*
1213          * this search will find all the extents that end after
1214          * our range starts.
1215          */
1216         node = tree_search_for_insert(tree, start, &p, &parent);
1217         if (!node) {
1218                 prealloc = alloc_extent_state_atomic(prealloc);
1219                 if (!prealloc) {
1220                         err = -ENOMEM;
1221                         goto out;
1222                 }
1223                 err = insert_state(tree, prealloc, start, end,
1224                                    &p, &parent, &bits, NULL);
1225                 if (err)
1226                         extent_io_tree_panic(tree, err);
1227                 cache_state(prealloc, cached_state);
1228                 prealloc = NULL;
1229                 goto out;
1230         }
1231         state = rb_entry(node, struct extent_state, rb_node);
1232 hit_next:
1233         last_start = state->start;
1234         last_end = state->end;
1235 
1236         /*
1237          * | ---- desired range ---- |
1238          * | state |
1239          *
1240          * Just lock what we found and keep going
1241          */
1242         if (state->start == start && state->end <= end) {
1243                 set_state_bits(tree, state, &bits, NULL);
1244                 cache_state(state, cached_state);
1245                 state = clear_state_bit(tree, state, &clear_bits, 0, NULL);
1246                 if (last_end == (u64)-1)
1247                         goto out;
1248                 start = last_end + 1;
1249                 if (start < end && state && state->start == start &&
1250                     !need_resched())
1251                         goto hit_next;
1252                 goto search_again;
1253         }
1254 
1255         /*
1256          *     | ---- desired range ---- |
1257          * | state |
1258          *   or
1259          * | ------------- state -------------- |
1260          *
1261          * We need to split the extent we found, and may flip bits on
1262          * second half.
1263          *
1264          * If the extent we found extends past our
1265          * range, we just split and search again.  It'll get split
1266          * again the next time though.
1267          *
1268          * If the extent we found is inside our range, we set the
1269          * desired bit on it.
1270          */
1271         if (state->start < start) {
1272                 prealloc = alloc_extent_state_atomic(prealloc);
1273                 if (!prealloc) {
1274                         err = -ENOMEM;
1275                         goto out;
1276                 }
1277                 err = split_state(tree, state, prealloc, start);
1278                 if (err)
1279                         extent_io_tree_panic(tree, err);
1280                 prealloc = NULL;
1281                 if (err)
1282                         goto out;
1283                 if (state->end <= end) {
1284                         set_state_bits(tree, state, &bits, NULL);
1285                         cache_state(state, cached_state);
1286                         state = clear_state_bit(tree, state, &clear_bits, 0,
1287                                                 NULL);
1288                         if (last_end == (u64)-1)
1289                                 goto out;
1290                         start = last_end + 1;
1291                         if (start < end && state && state->start == start &&
1292                             !need_resched())
1293                                 goto hit_next;
1294                 }
1295                 goto search_again;
1296         }
1297         /*
1298          * | ---- desired range ---- |
1299          *     | state | or               | state |
1300          *
1301          * There's a hole, we need to insert something in it and
1302          * ignore the extent we found.
1303          */
1304         if (state->start > start) {
1305                 u64 this_end;
1306                 if (end < last_start)
1307                         this_end = end;
1308                 else
1309                         this_end = last_start - 1;
1310 
1311                 prealloc = alloc_extent_state_atomic(prealloc);
1312                 if (!prealloc) {
1313                         err = -ENOMEM;
1314                         goto out;
1315                 }
1316 
1317                 /*
1318                  * Avoid to free 'prealloc' if it can be merged with
1319                  * the later extent.
1320                  */
1321                 err = insert_state(tree, prealloc, start, this_end,
1322                                    NULL, NULL, &bits, NULL);
1323                 if (err)
1324                         extent_io_tree_panic(tree, err);
1325                 cache_state(prealloc, cached_state);
1326                 prealloc = NULL;
1327                 start = this_end + 1;
1328                 goto search_again;
1329         }
1330         /*
1331          * | ---- desired range ---- |
1332          *                        | state |
1333          * We need to split the extent, and set the bit
1334          * on the first half
1335          */
1336         if (state->start <= end && state->end > end) {
1337                 prealloc = alloc_extent_state_atomic(prealloc);
1338                 if (!prealloc) {
1339                         err = -ENOMEM;
1340                         goto out;
1341                 }
1342 
1343                 err = split_state(tree, state, prealloc, end + 1);
1344                 if (err)
1345                         extent_io_tree_panic(tree, err);
1346 
1347                 set_state_bits(tree, prealloc, &bits, NULL);
1348                 cache_state(prealloc, cached_state);
1349                 clear_state_bit(tree, prealloc, &clear_bits, 0, NULL);
1350                 prealloc = NULL;
1351                 goto out;
1352         }
1353 
1354 search_again:
1355         if (start > end)
1356                 goto out;
1357         spin_unlock(&tree->lock);
1358         cond_resched();
1359         first_iteration = false;
1360         goto again;
1361 
1362 out:
1363         spin_unlock(&tree->lock);
1364         if (prealloc)
1365                 free_extent_state(prealloc);
1366 
1367         return err;
1368 }
1369 
1370 /* wrappers around set/clear extent bit */
1371 int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1372                            unsigned bits, struct extent_changeset *changeset)
1373 {
1374         /*
1375          * We don't support EXTENT_LOCKED yet, as current changeset will
1376          * record any bits changed, so for EXTENT_LOCKED case, it will
1377          * either fail with -EEXIST or changeset will record the whole
1378          * range.
1379          */
1380         BUG_ON(bits & EXTENT_LOCKED);
1381 
1382         return __set_extent_bit(tree, start, end, bits, 0, NULL, NULL, GFP_NOFS,
1383                                 changeset);
1384 }
1385 
1386 int set_extent_bits_nowait(struct extent_io_tree *tree, u64 start, u64 end,
1387                            unsigned bits)
1388 {
1389         return __set_extent_bit(tree, start, end, bits, 0, NULL, NULL,
1390                                 GFP_NOWAIT, NULL);
1391 }
1392 
1393 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1394                      unsigned bits, int wake, int delete,
1395                      struct extent_state **cached)
1396 {
1397         return __clear_extent_bit(tree, start, end, bits, wake, delete,
1398                                   cached, GFP_NOFS, NULL);
1399 }
1400 
1401 int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1402                 unsigned bits, struct extent_changeset *changeset)
1403 {
1404         /*
1405          * Don't support EXTENT_LOCKED case, same reason as
1406          * set_record_extent_bits().
1407          */
1408         BUG_ON(bits & EXTENT_LOCKED);
1409 
1410         return __clear_extent_bit(tree, start, end, bits, 0, 0, NULL, GFP_NOFS,
1411                                   changeset);
1412 }
1413 
1414 /*
1415  * either insert or lock state struct between start and end use mask to tell
1416  * us if waiting is desired.
1417  */
1418 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1419                      struct extent_state **cached_state)
1420 {
1421         int err;
1422         u64 failed_start;
1423 
1424         while (1) {
1425                 err = __set_extent_bit(tree, start, end, EXTENT_LOCKED,
1426                                        EXTENT_LOCKED, &failed_start,
1427                                        cached_state, GFP_NOFS, NULL);
1428                 if (err == -EEXIST) {
1429                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1430                         start = failed_start;
1431                 } else
1432                         break;
1433                 WARN_ON(start > end);
1434         }
1435         return err;
1436 }
1437 
1438 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1439 {
1440         int err;
1441         u64 failed_start;
1442 
1443         err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1444                                &failed_start, NULL, GFP_NOFS, NULL);
1445         if (err == -EEXIST) {
1446                 if (failed_start > start)
1447                         clear_extent_bit(tree, start, failed_start - 1,
1448                                          EXTENT_LOCKED, 1, 0, NULL);
1449                 return 0;
1450         }
1451         return 1;
1452 }
1453 
1454 void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
1455 {
1456         unsigned long index = start >> PAGE_SHIFT;
1457         unsigned long end_index = end >> PAGE_SHIFT;
1458         struct page *page;
1459 
1460         while (index <= end_index) {
1461                 page = find_get_page(inode->i_mapping, index);
1462                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1463                 clear_page_dirty_for_io(page);
1464                 put_page(page);
1465                 index++;
1466         }
1467 }
1468 
1469 void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
1470 {
1471         unsigned long index = start >> PAGE_SHIFT;
1472         unsigned long end_index = end >> PAGE_SHIFT;
1473         struct page *page;
1474 
1475         while (index <= end_index) {
1476                 page = find_get_page(inode->i_mapping, index);
1477                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1478                 __set_page_dirty_nobuffers(page);
1479                 account_page_redirty(page);
1480                 put_page(page);
1481                 index++;
1482         }
1483 }
1484 
1485 /* find the first state struct with 'bits' set after 'start', and
1486  * return it.  tree->lock must be held.  NULL will returned if
1487  * nothing was found after 'start'
1488  */
1489 static struct extent_state *
1490 find_first_extent_bit_state(struct extent_io_tree *tree,
1491                             u64 start, unsigned bits)
1492 {
1493         struct rb_node *node;
1494         struct extent_state *state;
1495 
1496         /*
1497          * this search will find all the extents that end after
1498          * our range starts.
1499          */
1500         node = tree_search(tree, start);
1501         if (!node)
1502                 goto out;
1503 
1504         while (1) {
1505                 state = rb_entry(node, struct extent_state, rb_node);
1506                 if (state->end >= start && (state->state & bits))
1507                         return state;
1508 
1509                 node = rb_next(node);
1510                 if (!node)
1511                         break;
1512         }
1513 out:
1514         return NULL;
1515 }
1516 
1517 /*
1518  * find the first offset in the io tree with 'bits' set. zero is
1519  * returned if we find something, and *start_ret and *end_ret are
1520  * set to reflect the state struct that was found.
1521  *
1522  * If nothing was found, 1 is returned. If found something, return 0.
1523  */
1524 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1525                           u64 *start_ret, u64 *end_ret, unsigned bits,
1526                           struct extent_state **cached_state)
1527 {
1528         struct extent_state *state;
1529         int ret = 1;
1530 
1531         spin_lock(&tree->lock);
1532         if (cached_state && *cached_state) {
1533                 state = *cached_state;
1534                 if (state->end == start - 1 && extent_state_in_tree(state)) {
1535                         while ((state = next_state(state)) != NULL) {
1536                                 if (state->state & bits)
1537                                         goto got_it;
1538                         }
1539                         free_extent_state(*cached_state);
1540                         *cached_state = NULL;
1541                         goto out;
1542                 }
1543                 free_extent_state(*cached_state);
1544                 *cached_state = NULL;
1545         }
1546 
1547         state = find_first_extent_bit_state(tree, start, bits);
1548 got_it:
1549         if (state) {
1550                 cache_state_if_flags(state, cached_state, 0);
1551                 *start_ret = state->start;
1552                 *end_ret = state->end;
1553                 ret = 0;
1554         }
1555 out:
1556         spin_unlock(&tree->lock);
1557         return ret;
1558 }
1559 
1560 /**
1561  * find_first_clear_extent_bit - find the first range that has @bits not set.
1562  * This range could start before @start.
1563  *
1564  * @tree - the tree to search
1565  * @start - the offset at/after which the found extent should start
1566  * @start_ret - records the beginning of the range
1567  * @end_ret - records the end of the range (inclusive)
1568  * @bits - the set of bits which must be unset
1569  *
1570  * Since unallocated range is also considered one which doesn't have the bits
1571  * set it's possible that @end_ret contains -1, this happens in case the range
1572  * spans (last_range_end, end of device]. In this case it's up to the caller to
1573  * trim @end_ret to the appropriate size.
1574  */
1575 void find_first_clear_extent_bit(struct extent_io_tree *tree, u64 start,
1576                                  u64 *start_ret, u64 *end_ret, unsigned bits)
1577 {
1578         struct extent_state *state;
1579         struct rb_node *node, *prev = NULL, *next;
1580 
1581         spin_lock(&tree->lock);
1582 
1583         /* Find first extent with bits cleared */
1584         while (1) {
1585                 node = __etree_search(tree, start, &next, &prev, NULL, NULL);
1586                 if (!node && !next && !prev) {
1587                         /*
1588                          * Tree is completely empty, send full range and let
1589                          * caller deal with it
1590                          */
1591                         *start_ret = 0;
1592                         *end_ret = -1;
1593                         goto out;
1594                 } else if (!node && !next) {
1595                         /*
1596                          * We are past the last allocated chunk, set start at
1597                          * the end of the last extent.
1598                          */
1599                         state = rb_entry(prev, struct extent_state, rb_node);
1600                         *start_ret = state->end + 1;
1601                         *end_ret = -1;
1602                         goto out;
1603                 } else if (!node) {
1604                         node = next;
1605                 }
1606                 /*
1607                  * At this point 'node' either contains 'start' or start is
1608                  * before 'node'
1609                  */
1610                 state = rb_entry(node, struct extent_state, rb_node);
1611 
1612                 if (in_range(start, state->start, state->end - state->start + 1)) {
1613                         if (state->state & bits) {
1614                                 /*
1615                                  * |--range with bits sets--|
1616                                  *    |
1617                                  *    start
1618                                  */
1619                                 start = state->end + 1;
1620                         } else {
1621                                 /*
1622                                  * 'start' falls within a range that doesn't
1623                                  * have the bits set, so take its start as
1624                                  * the beginning of the desired range
1625                                  *
1626                                  * |--range with bits cleared----|
1627                                  *      |
1628                                  *      start
1629                                  */
1630                                 *start_ret = state->start;
1631                                 break;
1632                         }
1633                 } else {
1634                         /*
1635                          * |---prev range---|---hole/unset---|---node range---|
1636                          *                          |
1637                          *                        start
1638                          *
1639                          *                        or
1640                          *
1641                          * |---hole/unset--||--first node--|
1642                          * 0   |
1643                          *    start
1644                          */
1645                         if (prev) {
1646                                 state = rb_entry(prev, struct extent_state,
1647                                                  rb_node);
1648                                 *start_ret = state->end + 1;
1649                         } else {
1650                                 *start_ret = 0;
1651                         }
1652                         break;
1653                 }
1654         }
1655 
1656         /*
1657          * Find the longest stretch from start until an entry which has the
1658          * bits set
1659          */
1660         while (1) {
1661                 state = rb_entry(node, struct extent_state, rb_node);
1662                 if (state->end >= start && !(state->state & bits)) {
1663                         *end_ret = state->end;
1664                 } else {
1665                         *end_ret = state->start - 1;
1666                         break;
1667                 }
1668 
1669                 node = rb_next(node);
1670                 if (!node)
1671                         break;
1672         }
1673 out:
1674         spin_unlock(&tree->lock);
1675 }
1676 
1677 /*
1678  * find a contiguous range of bytes in the file marked as delalloc, not
1679  * more than 'max_bytes'.  start and end are used to return the range,
1680  *
1681  * true is returned if we find something, false if nothing was in the tree
1682  */
1683 static noinline bool find_delalloc_range(struct extent_io_tree *tree,
1684                                         u64 *start, u64 *end, u64 max_bytes,
1685                                         struct extent_state **cached_state)
1686 {
1687         struct rb_node *node;
1688         struct extent_state *state;
1689         u64 cur_start = *start;
1690         bool found = false;
1691         u64 total_bytes = 0;
1692 
1693         spin_lock(&tree->lock);
1694 
1695         /*
1696          * this search will find all the extents that end after
1697          * our range starts.
1698          */
1699         node = tree_search(tree, cur_start);
1700         if (!node) {
1701                 *end = (u64)-1;
1702                 goto out;
1703         }
1704 
1705         while (1) {
1706                 state = rb_entry(node, struct extent_state, rb_node);
1707                 if (found && (state->start != cur_start ||
1708                               (state->state & EXTENT_BOUNDARY))) {
1709                         goto out;
1710                 }
1711                 if (!(state->state & EXTENT_DELALLOC)) {
1712                         if (!found)
1713                                 *end = state->end;
1714                         goto out;
1715                 }
1716                 if (!found) {
1717                         *start = state->start;
1718                         *cached_state = state;
1719                         refcount_inc(&state->refs);
1720                 }
1721                 found = true;
1722                 *end = state->end;
1723                 cur_start = state->end + 1;
1724                 node = rb_next(node);
1725                 total_bytes += state->end - state->start + 1;
1726                 if (total_bytes >= max_bytes)
1727                         break;
1728                 if (!node)
1729                         break;
1730         }
1731 out:
1732         spin_unlock(&tree->lock);
1733         return found;
1734 }
1735 
1736 static int __process_pages_contig(struct address_space *mapping,
1737                                   struct page *locked_page,
1738                                   pgoff_t start_index, pgoff_t end_index,
1739                                   unsigned long page_ops, pgoff_t *index_ret);
1740 
1741 static noinline void __unlock_for_delalloc(struct inode *inode,
1742                                            struct page *locked_page,
1743                                            u64 start, u64 end)
1744 {
1745         unsigned long index = start >> PAGE_SHIFT;
1746         unsigned long end_index = end >> PAGE_SHIFT;
1747 
1748         ASSERT(locked_page);
1749         if (index == locked_page->index && end_index == index)
1750                 return;
1751 
1752         __process_pages_contig(inode->i_mapping, locked_page, index, end_index,
1753                                PAGE_UNLOCK, NULL);
1754 }
1755 
1756 static noinline int lock_delalloc_pages(struct inode *inode,
1757                                         struct page *locked_page,
1758                                         u64 delalloc_start,
1759                                         u64 delalloc_end)
1760 {
1761         unsigned long index = delalloc_start >> PAGE_SHIFT;
1762         unsigned long index_ret = index;
1763         unsigned long end_index = delalloc_end >> PAGE_SHIFT;
1764         int ret;
1765 
1766         ASSERT(locked_page);
1767         if (index == locked_page->index && index == end_index)
1768                 return 0;
1769 
1770         ret = __process_pages_contig(inode->i_mapping, locked_page, index,
1771                                      end_index, PAGE_LOCK, &index_ret);
1772         if (ret == -EAGAIN)
1773                 __unlock_for_delalloc(inode, locked_page, delalloc_start,
1774                                       (u64)index_ret << PAGE_SHIFT);
1775         return ret;
1776 }
1777 
1778 /*
1779  * Find and lock a contiguous range of bytes in the file marked as delalloc, no
1780  * more than @max_bytes.  @Start and @end are used to return the range,
1781  *
1782  * Return: true if we find something
1783  *         false if nothing was in the tree
1784  */
1785 EXPORT_FOR_TESTS
1786 noinline_for_stack bool find_lock_delalloc_range(struct inode *inode,
1787                                     struct page *locked_page, u64 *start,
1788                                     u64 *end)
1789 {
1790         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
1791         u64 max_bytes = BTRFS_MAX_EXTENT_SIZE;
1792         u64 delalloc_start;
1793         u64 delalloc_end;
1794         bool found;
1795         struct extent_state *cached_state = NULL;
1796         int ret;
1797         int loops = 0;
1798 
1799 again:
1800         /* step one, find a bunch of delalloc bytes starting at start */
1801         delalloc_start = *start;
1802         delalloc_end = 0;
1803         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1804                                     max_bytes, &cached_state);
1805         if (!found || delalloc_end <= *start) {
1806                 *start = delalloc_start;
1807                 *end = delalloc_end;
1808                 free_extent_state(cached_state);
1809                 return false;
1810         }
1811 
1812         /*
1813          * start comes from the offset of locked_page.  We have to lock
1814          * pages in order, so we can't process delalloc bytes before
1815          * locked_page
1816          */
1817         if (delalloc_start < *start)
1818                 delalloc_start = *start;
1819 
1820         /*
1821          * make sure to limit the number of pages we try to lock down
1822          */
1823         if (delalloc_end + 1 - delalloc_start > max_bytes)
1824                 delalloc_end = delalloc_start + max_bytes - 1;
1825 
1826         /* step two, lock all the pages after the page that has start */
1827         ret = lock_delalloc_pages(inode, locked_page,
1828                                   delalloc_start, delalloc_end);
1829         ASSERT(!ret || ret == -EAGAIN);
1830         if (ret == -EAGAIN) {
1831                 /* some of the pages are gone, lets avoid looping by
1832                  * shortening the size of the delalloc range we're searching
1833                  */
1834                 free_extent_state(cached_state);
1835                 cached_state = NULL;
1836                 if (!loops) {
1837                         max_bytes = PAGE_SIZE;
1838                         loops = 1;
1839                         goto again;
1840                 } else {
1841                         found = false;
1842                         goto out_failed;
1843                 }
1844         }
1845 
1846         /* step three, lock the state bits for the whole range */
1847         lock_extent_bits(tree, delalloc_start, delalloc_end, &cached_state);
1848 
1849         /* then test to make sure it is all still delalloc */
1850         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1851                              EXTENT_DELALLOC, 1, cached_state);
1852         if (!ret) {
1853                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1854                                      &cached_state);
1855                 __unlock_for_delalloc(inode, locked_page,
1856                               delalloc_start, delalloc_end);
1857                 cond_resched();
1858                 goto again;
1859         }
1860         free_extent_state(cached_state);
1861         *start = delalloc_start;
1862         *end = delalloc_end;
1863 out_failed:
1864         return found;
1865 }
1866 
1867 static int __process_pages_contig(struct address_space *mapping,
1868                                   struct page *locked_page,
1869                                   pgoff_t start_index, pgoff_t end_index,
1870                                   unsigned long page_ops, pgoff_t *index_ret)
1871 {
1872         unsigned long nr_pages = end_index - start_index + 1;
1873         unsigned long pages_locked = 0;
1874         pgoff_t index = start_index;
1875         struct page *pages[16];
1876         unsigned ret;
1877         int err = 0;
1878         int i;
1879 
1880         if (page_ops & PAGE_LOCK) {
1881                 ASSERT(page_ops == PAGE_LOCK);
1882                 ASSERT(index_ret && *index_ret == start_index);
1883         }
1884 
1885         if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
1886                 mapping_set_error(mapping, -EIO);
1887 
1888         while (nr_pages > 0) {
1889                 ret = find_get_pages_contig(mapping, index,
1890                                      min_t(unsigned long,
1891                                      nr_pages, ARRAY_SIZE(pages)), pages);
1892                 if (ret == 0) {
1893                         /*
1894                          * Only if we're going to lock these pages,
1895                          * can we find nothing at @index.
1896                          */
1897                         ASSERT(page_ops & PAGE_LOCK);
1898                         err = -EAGAIN;
1899                         goto out;
1900                 }
1901 
1902                 for (i = 0; i < ret; i++) {
1903                         if (page_ops & PAGE_SET_PRIVATE2)
1904                                 SetPagePrivate2(pages[i]);
1905 
1906                         if (locked_page && pages[i] == locked_page) {
1907                                 put_page(pages[i]);
1908                                 pages_locked++;
1909                                 continue;
1910                         }
1911                         if (page_ops & PAGE_CLEAR_DIRTY)
1912                                 clear_page_dirty_for_io(pages[i]);
1913                         if (page_ops & PAGE_SET_WRITEBACK)
1914                                 set_page_writeback(pages[i]);
1915                         if (page_ops & PAGE_SET_ERROR)
1916                                 SetPageError(pages[i]);
1917                         if (page_ops & PAGE_END_WRITEBACK)
1918                                 end_page_writeback(pages[i]);
1919                         if (page_ops & PAGE_UNLOCK)
1920                                 unlock_page(pages[i]);
1921                         if (page_ops & PAGE_LOCK) {
1922                                 lock_page(pages[i]);
1923                                 if (!PageDirty(pages[i]) ||
1924                                     pages[i]->mapping != mapping) {
1925                                         unlock_page(pages[i]);
1926                                         put_page(pages[i]);
1927                                         err = -EAGAIN;
1928                                         goto out;
1929                                 }
1930                         }
1931                         put_page(pages[i]);
1932                         pages_locked++;
1933                 }
1934                 nr_pages -= ret;
1935                 index += ret;
1936                 cond_resched();
1937         }
1938 out:
1939         if (err && index_ret)
1940                 *index_ret = start_index + pages_locked - 1;
1941         return err;
1942 }
1943 
1944 void extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
1945                                   struct page *locked_page,
1946                                   unsigned clear_bits,
1947                                   unsigned long page_ops)
1948 {
1949         clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, clear_bits, 1, 0,
1950                          NULL);
1951 
1952         __process_pages_contig(inode->i_mapping, locked_page,
1953                                start >> PAGE_SHIFT, end >> PAGE_SHIFT,
1954                                page_ops, NULL);
1955 }
1956 
1957 /*
1958  * count the number of bytes in the tree that have a given bit(s)
1959  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1960  * cached.  The total number found is returned.
1961  */
1962 u64 count_range_bits(struct extent_io_tree *tree,
1963                      u64 *start, u64 search_end, u64 max_bytes,
1964                      unsigned bits, int contig)
1965 {
1966         struct rb_node *node;
1967         struct extent_state *state;
1968         u64 cur_start = *start;
1969         u64 total_bytes = 0;
1970         u64 last = 0;
1971         int found = 0;
1972 
1973         if (WARN_ON(search_end <= cur_start))
1974                 return 0;
1975 
1976         spin_lock(&tree->lock);
1977         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1978                 total_bytes = tree->dirty_bytes;
1979                 goto out;
1980         }
1981         /*
1982          * this search will find all the extents that end after
1983          * our range starts.
1984          */
1985         node = tree_search(tree, cur_start);
1986         if (!node)
1987                 goto out;
1988 
1989         while (1) {
1990                 state = rb_entry(node, struct extent_state, rb_node);
1991                 if (state->start > search_end)
1992                         break;
1993                 if (contig && found && state->start > last + 1)
1994                         break;
1995                 if (state->end >= cur_start && (state->state & bits) == bits) {
1996                         total_bytes += min(search_end, state->end) + 1 -
1997                                        max(cur_start, state->start);
1998                         if (total_bytes >= max_bytes)
1999                                 break;
2000                         if (!found) {
2001                                 *start = max(cur_start, state->start);
2002                                 found = 1;
2003                         }
2004                         last = state->end;
2005                 } else if (contig && found) {
2006                         break;
2007                 }
2008                 node = rb_next(node);
2009                 if (!node)
2010                         break;
2011         }
2012 out:
2013         spin_unlock(&tree->lock);
2014         return total_bytes;
2015 }
2016 
2017 /*
2018  * set the private field for a given byte offset in the tree.  If there isn't
2019  * an extent_state there already, this does nothing.
2020  */
2021 static noinline int set_state_failrec(struct extent_io_tree *tree, u64 start,
2022                 struct io_failure_record *failrec)
2023 {
2024         struct rb_node *node;
2025         struct extent_state *state;
2026         int ret = 0;
2027 
2028         spin_lock(&tree->lock);
2029         /*
2030          * this search will find all the extents that end after
2031          * our range starts.
2032          */
2033         node = tree_search(tree, start);
2034         if (!node) {
2035                 ret = -ENOENT;
2036                 goto out;
2037         }
2038         state = rb_entry(node, struct extent_state, rb_node);
2039         if (state->start != start) {
2040                 ret = -ENOENT;
2041                 goto out;
2042         }
2043         state->failrec = failrec;
2044 out:
2045         spin_unlock(&tree->lock);
2046         return ret;
2047 }
2048 
2049 static noinline int get_state_failrec(struct extent_io_tree *tree, u64 start,
2050                 struct io_failure_record **failrec)
2051 {
2052         struct rb_node *node;
2053         struct extent_state *state;
2054         int ret = 0;
2055 
2056         spin_lock(&tree->lock);
2057         /*
2058          * this search will find all the extents that end after
2059          * our range starts.
2060          */
2061         node = tree_search(tree, start);
2062         if (!node) {
2063                 ret = -ENOENT;
2064                 goto out;
2065         }
2066         state = rb_entry(node, struct extent_state, rb_node);
2067         if (state->start != start) {
2068                 ret = -ENOENT;
2069                 goto out;
2070         }
2071         *failrec = state->failrec;
2072 out:
2073         spin_unlock(&tree->lock);
2074         return ret;
2075 }
2076 
2077 /*
2078  * searches a range in the state tree for a given mask.
2079  * If 'filled' == 1, this returns 1 only if every extent in the tree
2080  * has the bits set.  Otherwise, 1 is returned if any bit in the
2081  * range is found set.
2082  */
2083 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
2084                    unsigned bits, int filled, struct extent_state *cached)
2085 {
2086         struct extent_state *state = NULL;
2087         struct rb_node *node;
2088         int bitset = 0;
2089 
2090         spin_lock(&tree->lock);
2091         if (cached && extent_state_in_tree(cached) && cached->start <= start &&
2092             cached->end > start)
2093                 node = &cached->rb_node;
2094         else
2095                 node = tree_search(tree, start);
2096         while (node && start <= end) {
2097                 state = rb_entry(node, struct extent_state, rb_node);
2098 
2099                 if (filled && state->start > start) {
2100                         bitset = 0;
2101                         break;
2102                 }
2103 
2104                 if (state->start > end)
2105                         break;
2106 
2107                 if (state->state & bits) {
2108                         bitset = 1;
2109                         if (!filled)
2110                                 break;
2111                 } else if (filled) {
2112                         bitset = 0;
2113                         break;
2114                 }
2115 
2116                 if (state->end == (u64)-1)
2117                         break;
2118 
2119                 start = state->end + 1;
2120                 if (start > end)
2121                         break;
2122                 node = rb_next(node);
2123                 if (!node) {
2124                         if (filled)
2125                                 bitset = 0;
2126                         break;
2127                 }
2128         }
2129         spin_unlock(&tree->lock);
2130         return bitset;
2131 }
2132 
2133 /*
2134  * helper function to set a given page up to date if all the
2135  * extents in the tree for that page are up to date
2136  */
2137 static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
2138 {
2139         u64 start = page_offset(page);
2140         u64 end = start + PAGE_SIZE - 1;
2141         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
2142                 SetPageUptodate(page);
2143 }
2144 
2145 int free_io_failure(struct extent_io_tree *failure_tree,
2146                     struct extent_io_tree *io_tree,
2147                     struct io_failure_record *rec)
2148 {
2149         int ret;
2150         int err = 0;
2151 
2152         set_state_failrec(failure_tree, rec->start, NULL);
2153         ret = clear_extent_bits(failure_tree, rec->start,
2154                                 rec->start + rec->len - 1,
2155                                 EXTENT_LOCKED | EXTENT_DIRTY);
2156         if (ret)
2157                 err = ret;
2158 
2159         ret = clear_extent_bits(io_tree, rec->start,
2160                                 rec->start + rec->len - 1,
2161                                 EXTENT_DAMAGED);
2162         if (ret && !err)
2163                 err = ret;
2164 
2165         kfree(rec);
2166         return err;
2167 }
2168 
2169 /*
2170  * this bypasses the standard btrfs submit functions deliberately, as
2171  * the standard behavior is to write all copies in a raid setup. here we only
2172  * want to write the one bad copy. so we do the mapping for ourselves and issue
2173  * submit_bio directly.
2174  * to avoid any synchronization issues, wait for the data after writing, which
2175  * actually prevents the read that triggered the error from finishing.
2176  * currently, there can be no more than two copies of every data bit. thus,
2177  * exactly one rewrite is required.
2178  */
2179 int repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
2180                       u64 length, u64 logical, struct page *page,
2181                       unsigned int pg_offset, int mirror_num)
2182 {
2183         struct bio *bio;
2184         struct btrfs_device *dev;
2185         u64 map_length = 0;
2186         u64 sector;
2187         struct btrfs_bio *bbio = NULL;
2188         int ret;
2189 
2190         ASSERT(!(fs_info->sb->s_flags & SB_RDONLY));
2191         BUG_ON(!mirror_num);
2192 
2193         bio = btrfs_io_bio_alloc(1);
2194         bio->bi_iter.bi_size = 0;
2195         map_length = length;
2196 
2197         /*
2198          * Avoid races with device replace and make sure our bbio has devices
2199          * associated to its stripes that don't go away while we are doing the
2200          * read repair operation.
2201          */
2202         btrfs_bio_counter_inc_blocked(fs_info);
2203         if (btrfs_is_parity_mirror(fs_info, logical, length)) {
2204                 /*
2205                  * Note that we don't use BTRFS_MAP_WRITE because it's supposed
2206                  * to update all raid stripes, but here we just want to correct
2207                  * bad stripe, thus BTRFS_MAP_READ is abused to only get the bad
2208                  * stripe's dev and sector.
2209                  */
2210                 ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, logical,
2211                                       &map_length, &bbio, 0);
2212                 if (ret) {
2213                         btrfs_bio_counter_dec(fs_info);
2214                         bio_put(bio);
2215                         return -EIO;
2216                 }
2217                 ASSERT(bbio->mirror_num == 1);
2218         } else {
2219                 ret = btrfs_map_block(fs_info, BTRFS_MAP_WRITE, logical,
2220                                       &map_length, &bbio, mirror_num);
2221                 if (ret) {
2222                         btrfs_bio_counter_dec(fs_info);
2223                         bio_put(bio);
2224                         return -EIO;
2225                 }
2226                 BUG_ON(mirror_num != bbio->mirror_num);
2227         }
2228 
2229         sector = bbio->stripes[bbio->mirror_num - 1].physical >> 9;
2230         bio->bi_iter.bi_sector = sector;
2231         dev = bbio->stripes[bbio->mirror_num - 1].dev;
2232         btrfs_put_bbio(bbio);
2233         if (!dev || !dev->bdev ||
2234             !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
2235                 btrfs_bio_counter_dec(fs_info);
2236                 bio_put(bio);
2237                 return -EIO;
2238         }
2239         bio_set_dev(bio, dev->bdev);
2240         bio->bi_opf = REQ_OP_WRITE | REQ_SYNC;
2241         bio_add_page(bio, page, length, pg_offset);
2242 
2243         if (btrfsic_submit_bio_wait(bio)) {
2244                 /* try to remap that extent elsewhere? */
2245                 btrfs_bio_counter_dec(fs_info);
2246                 bio_put(bio);
2247                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
2248                 return -EIO;
2249         }
2250 
2251         btrfs_info_rl_in_rcu(fs_info,
2252                 "read error corrected: ino %llu off %llu (dev %s sector %llu)",
2253                                   ino, start,
2254                                   rcu_str_deref(dev->name), sector);
2255         btrfs_bio_counter_dec(fs_info);
2256         bio_put(bio);
2257         return 0;
2258 }
2259 
2260 int btrfs_repair_eb_io_failure(struct extent_buffer *eb, int mirror_num)
2261 {
2262         struct btrfs_fs_info *fs_info = eb->fs_info;
2263         u64 start = eb->start;
2264         int i, num_pages = num_extent_pages(eb);
2265         int ret = 0;
2266 
2267         if (sb_rdonly(fs_info->sb))
2268                 return -EROFS;
2269 
2270         for (i = 0; i < num_pages; i++) {
2271                 struct page *p = eb->pages[i];
2272 
2273                 ret = repair_io_failure(fs_info, 0, start, PAGE_SIZE, start, p,
2274                                         start - page_offset(p), mirror_num);
2275                 if (ret)
2276                         break;
2277                 start += PAGE_SIZE;
2278         }
2279 
2280         return ret;
2281 }
2282 
2283 /*
2284  * each time an IO finishes, we do a fast check in the IO failure tree
2285  * to see if we need to process or clean up an io_failure_record
2286  */
2287 int clean_io_failure(struct btrfs_fs_info *fs_info,
2288                      struct extent_io_tree *failure_tree,
2289                      struct extent_io_tree *io_tree, u64 start,
2290                      struct page *page, u64 ino, unsigned int pg_offset)
2291 {
2292         u64 private;
2293         struct io_failure_record *failrec;
2294         struct extent_state *state;
2295         int num_copies;
2296         int ret;
2297 
2298         private = 0;
2299         ret = count_range_bits(failure_tree, &private, (u64)-1, 1,
2300                                EXTENT_DIRTY, 0);
2301         if (!ret)
2302                 return 0;
2303 
2304         ret = get_state_failrec(failure_tree, start, &failrec);
2305         if (ret)
2306                 return 0;
2307 
2308         BUG_ON(!failrec->this_mirror);
2309 
2310         if (failrec->in_validation) {
2311                 /* there was no real error, just free the record */
2312                 btrfs_debug(fs_info,
2313                         "clean_io_failure: freeing dummy error at %llu",
2314                         failrec->start);
2315                 goto out;
2316         }
2317         if (sb_rdonly(fs_info->sb))
2318                 goto out;
2319 
2320         spin_lock(&io_tree->lock);
2321         state = find_first_extent_bit_state(io_tree,
2322                                             failrec->start,
2323                                             EXTENT_LOCKED);
2324         spin_unlock(&io_tree->lock);
2325 
2326         if (state && state->start <= failrec->start &&
2327             state->end >= failrec->start + failrec->len - 1) {
2328                 num_copies = btrfs_num_copies(fs_info, failrec->logical,
2329                                               failrec->len);
2330                 if (num_copies > 1)  {
2331                         repair_io_failure(fs_info, ino, start, failrec->len,
2332                                           failrec->logical, page, pg_offset,
2333                                           failrec->failed_mirror);
2334                 }
2335         }
2336 
2337 out:
2338         free_io_failure(failure_tree, io_tree, failrec);
2339 
2340         return 0;
2341 }
2342 
2343 /*
2344  * Can be called when
2345  * - hold extent lock
2346  * - under ordered extent
2347  * - the inode is freeing
2348  */
2349 void btrfs_free_io_failure_record(struct btrfs_inode *inode, u64 start, u64 end)
2350 {
2351         struct extent_io_tree *failure_tree = &inode->io_failure_tree;
2352         struct io_failure_record *failrec;
2353         struct extent_state *state, *next;
2354 
2355         if (RB_EMPTY_ROOT(&failure_tree->state))
2356                 return;
2357 
2358         spin_lock(&failure_tree->lock);
2359         state = find_first_extent_bit_state(failure_tree, start, EXTENT_DIRTY);
2360         while (state) {
2361                 if (state->start > end)
2362                         break;
2363 
2364                 ASSERT(state->end <= end);
2365 
2366                 next = next_state(state);
2367 
2368                 failrec = state->failrec;
2369                 free_extent_state(state);
2370                 kfree(failrec);
2371 
2372                 state = next;
2373         }
2374         spin_unlock(&failure_tree->lock);
2375 }
2376 
2377 int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
2378                 struct io_failure_record **failrec_ret)
2379 {
2380         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2381         struct io_failure_record *failrec;
2382         struct extent_map *em;
2383         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2384         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2385         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2386         int ret;
2387         u64 logical;
2388 
2389         ret = get_state_failrec(failure_tree, start, &failrec);
2390         if (ret) {
2391                 failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
2392                 if (!failrec)
2393                         return -ENOMEM;
2394 
2395                 failrec->start = start;
2396                 failrec->len = end - start + 1;
2397                 failrec->this_mirror = 0;
2398                 failrec->bio_flags = 0;
2399                 failrec->in_validation = 0;
2400 
2401                 read_lock(&em_tree->lock);
2402                 em = lookup_extent_mapping(em_tree, start, failrec->len);
2403                 if (!em) {
2404                         read_unlock(&em_tree->lock);
2405                         kfree(failrec);
2406                         return -EIO;
2407                 }
2408 
2409                 if (em->start > start || em->start + em->len <= start) {
2410                         free_extent_map(em);
2411                         em = NULL;
2412                 }
2413                 read_unlock(&em_tree->lock);
2414                 if (!em) {
2415                         kfree(failrec);
2416                         return -EIO;
2417                 }
2418 
2419                 logical = start - em->start;
2420                 logical = em->block_start + logical;
2421                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2422                         logical = em->block_start;
2423                         failrec->bio_flags = EXTENT_BIO_COMPRESSED;
2424                         extent_set_compress_type(&failrec->bio_flags,
2425                                                  em->compress_type);
2426                 }
2427 
2428                 btrfs_debug(fs_info,
2429                         "Get IO Failure Record: (new) logical=%llu, start=%llu, len=%llu",
2430                         logical, start, failrec->len);
2431 
2432                 failrec->logical = logical;
2433                 free_extent_map(em);
2434 
2435                 /* set the bits in the private failure tree */
2436                 ret = set_extent_bits(failure_tree, start, end,
2437                                         EXTENT_LOCKED | EXTENT_DIRTY);
2438                 if (ret >= 0)
2439                         ret = set_state_failrec(failure_tree, start, failrec);
2440                 /* set the bits in the inode's tree */
2441                 if (ret >= 0)
2442                         ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED);
2443                 if (ret < 0) {
2444                         kfree(failrec);
2445                         return ret;
2446                 }
2447         } else {
2448                 btrfs_debug(fs_info,
2449                         "Get IO Failure Record: (found) logical=%llu, start=%llu, len=%llu, validation=%d",
2450                         failrec->logical, failrec->start, failrec->len,
2451                         failrec->in_validation);
2452                 /*
2453                  * when data can be on disk more than twice, add to failrec here
2454                  * (e.g. with a list for failed_mirror) to make
2455                  * clean_io_failure() clean all those errors at once.
2456                  */
2457         }
2458 
2459         *failrec_ret = failrec;
2460 
2461         return 0;
2462 }
2463 
2464 bool btrfs_check_repairable(struct inode *inode, unsigned failed_bio_pages,
2465                            struct io_failure_record *failrec, int failed_mirror)
2466 {
2467         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2468         int num_copies;
2469 
2470         num_copies = btrfs_num_copies(fs_info, failrec->logical, failrec->len);
2471         if (num_copies == 1) {
2472                 /*
2473                  * we only have a single copy of the data, so don't bother with
2474                  * all the retry and error correction code that follows. no
2475                  * matter what the error is, it is very likely to persist.
2476                  */
2477                 btrfs_debug(fs_info,
2478                         "Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d",
2479                         num_copies, failrec->this_mirror, failed_mirror);
2480                 return false;
2481         }
2482 
2483         /*
2484          * there are two premises:
2485          *      a) deliver good data to the caller
2486          *      b) correct the bad sectors on disk
2487          */
2488         if (failed_bio_pages > 1) {
2489                 /*
2490                  * to fulfill b), we need to know the exact failing sectors, as
2491                  * we don't want to rewrite any more than the failed ones. thus,
2492                  * we need separate read requests for the failed bio
2493                  *
2494                  * if the following BUG_ON triggers, our validation request got
2495                  * merged. we need separate requests for our algorithm to work.
2496                  */
2497                 BUG_ON(failrec->in_validation);
2498                 failrec->in_validation = 1;
2499                 failrec->this_mirror = failed_mirror;
2500         } else {
2501                 /*
2502                  * we're ready to fulfill a) and b) alongside. get a good copy
2503                  * of the failed sector and if we succeed, we have setup
2504                  * everything for repair_io_failure to do the rest for us.
2505                  */
2506                 if (failrec->in_validation) {
2507                         BUG_ON(failrec->this_mirror != failed_mirror);
2508                         failrec->in_validation = 0;
2509                         failrec->this_mirror = 0;
2510                 }
2511                 failrec->failed_mirror = failed_mirror;
2512                 failrec->this_mirror++;
2513                 if (failrec->this_mirror == failed_mirror)
2514                         failrec->this_mirror++;
2515         }
2516 
2517         if (failrec->this_mirror > num_copies) {
2518                 btrfs_debug(fs_info,
2519                         "Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d",
2520                         num_copies, failrec->this_mirror, failed_mirror);
2521                 return false;
2522         }
2523 
2524         return true;
2525 }
2526 
2527 
2528 struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
2529                                     struct io_failure_record *failrec,
2530                                     struct page *page, int pg_offset, int icsum,
2531                                     bio_end_io_t *endio_func, void *data)
2532 {
2533         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2534         struct bio *bio;
2535         struct btrfs_io_bio *btrfs_failed_bio;
2536         struct btrfs_io_bio *btrfs_bio;
2537 
2538         bio = btrfs_io_bio_alloc(1);
2539         bio->bi_end_io = endio_func;
2540         bio->bi_iter.bi_sector = failrec->logical >> 9;
2541         bio_set_dev(bio, fs_info->fs_devices->latest_bdev);
2542         bio->bi_iter.bi_size = 0;
2543         bio->bi_private = data;
2544 
2545         btrfs_failed_bio = btrfs_io_bio(failed_bio);
2546         if (btrfs_failed_bio->csum) {
2547                 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
2548 
2549                 btrfs_bio = btrfs_io_bio(bio);
2550                 btrfs_bio->csum = btrfs_bio->csum_inline;
2551                 icsum *= csum_size;
2552                 memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + icsum,
2553                        csum_size);
2554         }
2555 
2556         bio_add_page(bio, page, failrec->len, pg_offset);
2557 
2558         return bio;
2559 }
2560 
2561 /*
2562  * This is a generic handler for readpage errors. If other copies exist, read
2563  * those and write back good data to the failed position. Does not investigate
2564  * in remapping the failed extent elsewhere, hoping the device will be smart
2565  * enough to do this as needed
2566  */
2567 static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
2568                               struct page *page, u64 start, u64 end,
2569                               int failed_mirror)
2570 {
2571         struct io_failure_record *failrec;
2572         struct inode *inode = page->mapping->host;
2573         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2574         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2575         struct bio *bio;
2576         int read_mode = 0;
2577         blk_status_t status;
2578         int ret;
2579         unsigned failed_bio_pages = failed_bio->bi_iter.bi_size >> PAGE_SHIFT;
2580 
2581         BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);
2582 
2583         ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
2584         if (ret)
2585                 return ret;
2586 
2587         if (!btrfs_check_repairable(inode, failed_bio_pages, failrec,
2588                                     failed_mirror)) {
2589                 free_io_failure(failure_tree, tree, failrec);
2590                 return -EIO;
2591         }
2592 
2593         if (failed_bio_pages > 1)
2594                 read_mode |= REQ_FAILFAST_DEV;
2595 
2596         phy_offset >>= inode->i_sb->s_blocksize_bits;
2597         bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
2598                                       start - page_offset(page),
2599                                       (int)phy_offset, failed_bio->bi_end_io,
2600                                       NULL);
2601         bio->bi_opf = REQ_OP_READ | read_mode;
2602 
2603         btrfs_debug(btrfs_sb(inode->i_sb),
2604                 "Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d",
2605                 read_mode, failrec->this_mirror, failrec->in_validation);
2606 
2607         status = tree->ops->submit_bio_hook(tree->private_data, bio, failrec->this_mirror,
2608                                          failrec->bio_flags);
2609         if (status) {
2610                 free_io_failure(failure_tree, tree, failrec);
2611                 bio_put(bio);
2612                 ret = blk_status_to_errno(status);
2613         }
2614 
2615         return ret;
2616 }
2617 
2618 /* lots and lots of room for performance fixes in the end_bio funcs */
2619 
2620 void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
2621 {
2622         int uptodate = (err == 0);
2623         int ret = 0;
2624 
2625         btrfs_writepage_endio_finish_ordered(page, start, end, uptodate);
2626 
2627         if (!uptodate) {
2628                 ClearPageUptodate(page);
2629                 SetPageError(page);
2630                 ret = err < 0 ? err : -EIO;
2631                 mapping_set_error(page->mapping, ret);
2632         }
2633 }
2634 
2635 /*
2636  * after a writepage IO is done, we need to:
2637  * clear the uptodate bits on error
2638  * clear the writeback bits in the extent tree for this IO
2639  * end_page_writeback if the page has no more pending IO
2640  *
2641  * Scheduling is not allowed, so the extent state tree is expected
2642  * to have one and only one object corresponding to this IO.
2643  */
2644 static void end_bio_extent_writepage(struct bio *bio)
2645 {
2646         int error = blk_status_to_errno(bio->bi_status);
2647         struct bio_vec *bvec;
2648         u64 start;
2649         u64 end;
2650         struct bvec_iter_all iter_all;
2651 
2652         ASSERT(!bio_flagged(bio, BIO_CLONED));
2653         bio_for_each_segment_all(bvec, bio, iter_all) {
2654                 struct page *page = bvec->bv_page;
2655                 struct inode *inode = page->mapping->host;
2656                 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2657 
2658                 /* We always issue full-page reads, but if some block
2659                  * in a page fails to read, blk_update_request() will
2660                  * advance bv_offset and adjust bv_len to compensate.
2661                  * Print a warning for nonzero offsets, and an error
2662                  * if they don't add up to a full page.  */
2663                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2664                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2665                                 btrfs_err(fs_info,
2666                                    "partial page write in btrfs with offset %u and length %u",
2667                                         bvec->bv_offset, bvec->bv_len);
2668                         else
2669                                 btrfs_info(fs_info,
2670                                    "incomplete page write in btrfs with offset %u and length %u",
2671                                         bvec->bv_offset, bvec->bv_len);
2672                 }
2673 
2674                 start = page_offset(page);
2675                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2676 
2677                 end_extent_writepage(page, error, start, end);
2678                 end_page_writeback(page);
2679         }
2680 
2681         bio_put(bio);
2682 }
2683 
2684 static void
2685 endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
2686                               int uptodate)
2687 {
2688         struct extent_state *cached = NULL;
2689         u64 end = start + len - 1;
2690 
2691         if (uptodate && tree->track_uptodate)
2692                 set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
2693         unlock_extent_cached_atomic(tree, start, end, &cached);
2694 }
2695 
2696 /*
2697  * after a readpage IO is done, we need to:
2698  * clear the uptodate bits on error
2699  * set the uptodate bits if things worked
2700  * set the page up to date if all extents in the tree are uptodate
2701  * clear the lock bit in the extent tree
2702  * unlock the page if there are no other extents locked for it
2703  *
2704  * Scheduling is not allowed, so the extent state tree is expected
2705  * to have one and only one object corresponding to this IO.
2706  */
2707 static void end_bio_extent_readpage(struct bio *bio)
2708 {
2709         struct bio_vec *bvec;
2710         int uptodate = !bio->bi_status;
2711         struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
2712         struct extent_io_tree *tree, *failure_tree;
2713         u64 offset = 0;
2714         u64 start;
2715         u64 end;
2716         u64 len;
2717         u64 extent_start = 0;
2718         u64 extent_len = 0;
2719         int mirror;
2720         int ret;
2721         struct bvec_iter_all iter_all;
2722 
2723         ASSERT(!bio_flagged(bio, BIO_CLONED));
2724         bio_for_each_segment_all(bvec, bio, iter_all) {
2725                 struct page *page = bvec->bv_page;
2726                 struct inode *inode = page->mapping->host;
2727                 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2728                 bool data_inode = btrfs_ino(BTRFS_I(inode))
2729                         != BTRFS_BTREE_INODE_OBJECTID;
2730 
2731                 btrfs_debug(fs_info,
2732                         "end_bio_extent_readpage: bi_sector=%llu, err=%d, mirror=%u",
2733                         (u64)bio->bi_iter.bi_sector, bio->bi_status,
2734                         io_bio->mirror_num);
2735                 tree = &BTRFS_I(inode)->io_tree;
2736                 failure_tree = &BTRFS_I(inode)->io_failure_tree;
2737 
2738                 /* We always issue full-page reads, but if some block
2739                  * in a page fails to read, blk_update_request() will
2740                  * advance bv_offset and adjust bv_len to compensate.
2741                  * Print a warning for nonzero offsets, and an error
2742                  * if they don't add up to a full page.  */
2743                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2744                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2745                                 btrfs_err(fs_info,
2746                                         "partial page read in btrfs with offset %u and length %u",
2747                                         bvec->bv_offset, bvec->bv_len);
2748                         else
2749                                 btrfs_info(fs_info,
2750                                         "incomplete page read in btrfs with offset %u and length %u",
2751                                         bvec->bv_offset, bvec->bv_len);
2752                 }
2753 
2754                 start = page_offset(page);
2755                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2756                 len = bvec->bv_len;
2757 
2758                 mirror = io_bio->mirror_num;
2759                 if (likely(uptodate)) {
2760                         ret = tree->ops->readpage_end_io_hook(io_bio, offset,
2761                                                               page, start, end,
2762                                                               mirror);
2763                         if (ret)
2764                                 uptodate = 0;
2765                         else
2766                                 clean_io_failure(BTRFS_I(inode)->root->fs_info,
2767                                                  failure_tree, tree, start,
2768                                                  page,
2769                                                  btrfs_ino(BTRFS_I(inode)), 0);
2770                 }
2771 
2772                 if (likely(uptodate))
2773                         goto readpage_ok;
2774 
2775                 if (data_inode) {
2776 
2777                         /*
2778                          * The generic bio_readpage_error handles errors the
2779                          * following way: If possible, new read requests are
2780                          * created and submitted and will end up in
2781                          * end_bio_extent_readpage as well (if we're lucky,
2782                          * not in the !uptodate case). In that case it returns
2783                          * 0 and we just go on with the next page in our bio.
2784                          * If it can't handle the error it will return -EIO and
2785                          * we remain responsible for that page.
2786                          */
2787                         ret = bio_readpage_error(bio, offset, page, start, end,
2788                                                  mirror);
2789                         if (ret == 0) {
2790                                 uptodate = !bio->bi_status;
2791                                 offset += len;
2792                                 continue;
2793                         }
2794                 } else {
2795                         struct extent_buffer *eb;
2796 
2797                         eb = (struct extent_buffer *)page->private;
2798                         set_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
2799                         eb->read_mirror = mirror;
2800                         atomic_dec(&eb->io_pages);
2801                         if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD,
2802                                                &eb->bflags))
2803                                 btree_readahead_hook(eb, -EIO);
2804                 }
2805 readpage_ok:
2806                 if (likely(uptodate)) {
2807                         loff_t i_size = i_size_read(inode);
2808                         pgoff_t end_index = i_size >> PAGE_SHIFT;
2809                         unsigned off;
2810 
2811                         /* Zero out the end if this page straddles i_size */
2812                         off = offset_in_page(i_size);
2813                         if (page->index == end_index && off)
2814                                 zero_user_segment(page, off, PAGE_SIZE);
2815                         SetPageUptodate(page);
2816                 } else {
2817                         ClearPageUptodate(page);
2818                         SetPageError(page);
2819                 }
2820                 unlock_page(page);
2821                 offset += len;
2822 
2823                 if (unlikely(!uptodate)) {
2824                         if (extent_len) {
2825                                 endio_readpage_release_extent(tree,
2826                                                               extent_start,
2827                                                               extent_len, 1);
2828                                 extent_start = 0;
2829                                 extent_len = 0;
2830                         }
2831                         endio_readpage_release_extent(tree, start,
2832                                                       end - start + 1, 0);
2833                 } else if (!extent_len) {
2834                         extent_start = start;
2835                         extent_len = end + 1 - start;
2836                 } else if (extent_start + extent_len == start) {
2837                         extent_len += end + 1 - start;
2838                 } else {
2839                         endio_readpage_release_extent(tree, extent_start,
2840                                                       extent_len, uptodate);
2841                         extent_start = start;
2842                         extent_len = end + 1 - start;
2843                 }
2844         }
2845 
2846         if (extent_len)
2847                 endio_readpage_release_extent(tree, extent_start, extent_len,
2848                                               uptodate);
2849         btrfs_io_bio_free_csum(io_bio);
2850         bio_put(bio);
2851 }
2852 
2853 /*
2854  * Initialize the members up to but not including 'bio'. Use after allocating a
2855  * new bio by bio_alloc_bioset as it does not initialize the bytes outside of
2856  * 'bio' because use of __GFP_ZERO is not supported.
2857  */
2858 static inline void btrfs_io_bio_init(struct btrfs_io_bio *btrfs_bio)
2859 {
2860         memset(btrfs_bio, 0, offsetof(struct btrfs_io_bio, bio));
2861 }
2862 
2863 /*
2864  * The following helpers allocate a bio. As it's backed by a bioset, it'll
2865  * never fail.  We're returning a bio right now but you can call btrfs_io_bio
2866  * for the appropriate container_of magic
2867  */
2868 struct bio *btrfs_bio_alloc(u64 first_byte)
2869 {
2870         struct bio *bio;
2871 
2872         bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &btrfs_bioset);
2873         bio->bi_iter.bi_sector = first_byte >> 9;
2874         btrfs_io_bio_init(btrfs_io_bio(bio));
2875         return bio;
2876 }
2877 
2878 struct bio *btrfs_bio_clone(struct bio *bio)
2879 {
2880         struct btrfs_io_bio *btrfs_bio;
2881         struct bio *new;
2882 
2883         /* Bio allocation backed by a bioset does not fail */
2884         new = bio_clone_fast(bio, GFP_NOFS, &btrfs_bioset);
2885         btrfs_bio = btrfs_io_bio(new);
2886         btrfs_io_bio_init(btrfs_bio);
2887         btrfs_bio->iter = bio->bi_iter;
2888         return new;
2889 }
2890 
2891 struct bio *btrfs_io_bio_alloc(unsigned int nr_iovecs)
2892 {
2893         struct bio *bio;
2894 
2895         /* Bio allocation backed by a bioset does not fail */
2896         bio = bio_alloc_bioset(GFP_NOFS, nr_iovecs, &btrfs_bioset);
2897         btrfs_io_bio_init(btrfs_io_bio(bio));
2898         return bio;
2899 }
2900 
2901 struct bio *btrfs_bio_clone_partial(struct bio *orig, int offset, int size)
2902 {
2903         struct bio *bio;
2904         struct btrfs_io_bio *btrfs_bio;
2905 
2906         /* this will never fail when it's backed by a bioset */
2907         bio = bio_clone_fast(orig, GFP_NOFS, &btrfs_bioset);
2908         ASSERT(bio);
2909 
2910         btrfs_bio = btrfs_io_bio(bio);
2911         btrfs_io_bio_init(btrfs_bio);
2912 
2913         bio_trim(bio, offset >> 9, size >> 9);
2914         btrfs_bio->iter = bio->bi_iter;
2915         return bio;
2916 }
2917 
2918 /*
2919  * @opf:        bio REQ_OP_* and REQ_* flags as one value
2920  * @tree:       tree so we can call our merge_bio hook
2921  * @wbc:        optional writeback control for io accounting
2922  * @page:       page to add to the bio
2923  * @pg_offset:  offset of the new bio or to check whether we are adding
2924  *              a contiguous page to the previous one
2925  * @size:       portion of page that we want to write
2926  * @offset:     starting offset in the page
2927  * @bdev:       attach newly created bios to this bdev
2928  * @bio_ret:    must be valid pointer, newly allocated bio will be stored there
2929  * @end_io_func:     end_io callback for new bio
2930  * @mirror_num:      desired mirror to read/write
2931  * @prev_bio_flags:  flags of previous bio to see if we can merge the current one
2932  * @bio_flags:  flags of the current bio to see if we can merge them
2933  */
2934 static int submit_extent_page(unsigned int opf, struct extent_io_tree *tree,
2935                               struct writeback_control *wbc,
2936                               struct page *page, u64 offset,
2937                               size_t size, unsigned long pg_offset,
2938                               struct block_device *bdev,
2939                               struct bio **bio_ret,
2940                               bio_end_io_t end_io_func,
2941                               int mirror_num,
2942                               unsigned long prev_bio_flags,
2943                               unsigned long bio_flags,
2944                               bool force_bio_submit)
2945 {
2946         int ret = 0;
2947         struct bio *bio;
2948         size_t page_size = min_t(size_t, size, PAGE_SIZE);
2949         sector_t sector = offset >> 9;
2950 
2951         ASSERT(bio_ret);
2952 
2953         if (*bio_ret) {
2954                 bool contig;
2955                 bool can_merge = true;
2956 
2957                 bio = *bio_ret;
2958                 if (prev_bio_flags & EXTENT_BIO_COMPRESSED)
2959                         contig = bio->bi_iter.bi_sector == sector;
2960                 else
2961                         contig = bio_end_sector(bio) == sector;
2962 
2963                 ASSERT(tree->ops);
2964                 if (btrfs_bio_fits_in_stripe(page, page_size, bio, bio_flags))
2965                         can_merge = false;
2966 
2967                 if (prev_bio_flags != bio_flags || !contig || !can_merge ||
2968                     force_bio_submit ||
2969                     bio_add_page(bio, page, page_size, pg_offset) < page_size) {
2970                         ret = submit_one_bio(bio, mirror_num, prev_bio_flags);
2971                         if (ret < 0) {
2972                                 *bio_ret = NULL;
2973                                 return ret;
2974                         }
2975                         bio = NULL;
2976                 } else {
2977                         if (wbc)
2978                                 wbc_account_cgroup_owner(wbc, page, page_size);
2979                         return 0;
2980                 }
2981         }
2982 
2983         bio = btrfs_bio_alloc(offset);
2984         bio_set_dev(bio, bdev);
2985         bio_add_page(bio, page, page_size, pg_offset);
2986         bio->bi_end_io = end_io_func;
2987         bio->bi_private = tree;
2988         bio->bi_write_hint = page->mapping->host->i_write_hint;
2989         bio->bi_opf = opf;
2990         if (wbc) {
2991                 wbc_init_bio(wbc, bio);
2992                 wbc_account_cgroup_owner(wbc, page, page_size);
2993         }
2994 
2995         *bio_ret = bio;
2996 
2997         return ret;
2998 }
2999 
3000 static void attach_extent_buffer_page(struct extent_buffer *eb,
3001                                       struct page *page)
3002 {
3003         if (!PagePrivate(page)) {
3004                 SetPagePrivate(page);
3005                 get_page(page);
3006                 set_page_private(page, (unsigned long)eb);
3007         } else {
3008                 WARN_ON(page->private != (unsigned long)eb);
3009         }
3010 }
3011 
3012 void set_page_extent_mapped(struct page *page)
3013 {
3014         if (!PagePrivate(page)) {
3015                 SetPagePrivate(page);
3016                 get_page(page);
3017                 set_page_private(page, EXTENT_PAGE_PRIVATE);
3018         }
3019 }
3020 
3021 static struct extent_map *
3022 __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
3023                  u64 start, u64 len, get_extent_t *get_extent,
3024                  struct extent_map **em_cached)
3025 {
3026         struct extent_map *em;
3027 
3028         if (em_cached && *em_cached) {
3029                 em = *em_cached;
3030                 if (extent_map_in_tree(em) && start >= em->start &&
3031                     start < extent_map_end(em)) {
3032                         refcount_inc(&em->refs);
3033                         return em;
3034                 }
3035 
3036                 free_extent_map(em);
3037                 *em_cached = NULL;
3038         }
3039 
3040         em = get_extent(BTRFS_I(inode), page, pg_offset, start, len, 0);
3041         if (em_cached && !IS_ERR_OR_NULL(em)) {
3042                 BUG_ON(*em_cached);
3043                 refcount_inc(&em->refs);
3044                 *em_cached = em;
3045         }
3046         return em;
3047 }
3048 /*
3049  * basic readpage implementation.  Locked extent state structs are inserted
3050  * into the tree that are removed when the IO is done (by the end_io
3051  * handlers)
3052  * XXX JDM: This needs looking at to ensure proper page locking
3053  * return 0 on success, otherwise return error
3054  */
3055 static int __do_readpage(struct extent_io_tree *tree,
3056                          struct page *page,
3057                          get_extent_t *get_extent,
3058                          struct extent_map **em_cached,
3059                          struct bio **bio, int mirror_num,
3060                          unsigned long *bio_flags, unsigned int read_flags,
3061                          u64 *prev_em_start)
3062 {
3063         struct inode *inode = page->mapping->host;
3064         u64 start = page_offset(page);
3065         const u64 end = start + PAGE_SIZE - 1;
3066         u64 cur = start;
3067         u64 extent_offset;
3068         u64 last_byte = i_size_read(inode);
3069         u64 block_start;
3070         u64 cur_end;
3071         struct extent_map *em;
3072         struct block_device *bdev;
3073         int ret = 0;
3074         int nr = 0;
3075         size_t pg_offset = 0;
3076         size_t iosize;
3077         size_t disk_io_size;
3078         size_t blocksize = inode->i_sb->s_blocksize;
3079         unsigned long this_bio_flag = 0;
3080 
3081         set_page_extent_mapped(page);
3082 
3083         if (!PageUptodate(page)) {
3084                 if (cleancache_get_page(page) == 0) {
3085                         BUG_ON(blocksize != PAGE_SIZE);
3086                         unlock_extent(tree, start, end);
3087                         goto out;
3088                 }
3089         }
3090 
3091         if (page->index == last_byte >> PAGE_SHIFT) {
3092                 char *userpage;
3093                 size_t zero_offset = offset_in_page(last_byte);
3094 
3095                 if (zero_offset) {
3096                         iosize = PAGE_SIZE - zero_offset;
3097                         userpage = kmap_atomic(page);
3098                         memset(userpage + zero_offset, 0, iosize);
3099                         flush_dcache_page(page);
3100                         kunmap_atomic(userpage);
3101                 }
3102         }
3103         while (cur <= end) {
3104                 bool force_bio_submit = false;
3105                 u64 offset;
3106 
3107                 if (cur >= last_byte) {
3108                         char *userpage;
3109                         struct extent_state *cached = NULL;
3110 
3111                         iosize = PAGE_SIZE - pg_offset;
3112                         userpage = kmap_atomic(page);
3113                         memset(userpage + pg_offset, 0, iosize);
3114                         flush_dcache_page(page);
3115                         kunmap_atomic(userpage);
3116                         set_extent_uptodate(tree, cur, cur + iosize - 1,
3117                                             &cached, GFP_NOFS);
3118                         unlock_extent_cached(tree, cur,
3119                                              cur + iosize - 1, &cached);
3120                         break;
3121                 }
3122                 em = __get_extent_map(inode, page, pg_offset, cur,
3123                                       end - cur + 1, get_extent, em_cached);
3124                 if (IS_ERR_OR_NULL(em)) {
3125                         SetPageError(page);
3126                         unlock_extent(tree, cur, end);
3127                         break;
3128                 }
3129                 extent_offset = cur - em->start;
3130                 BUG_ON(extent_map_end(em) <= cur);
3131                 BUG_ON(end < cur);
3132 
3133                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
3134                         this_bio_flag |= EXTENT_BIO_COMPRESSED;
3135                         extent_set_compress_type(&this_bio_flag,
3136                                                  em->compress_type);
3137                 }
3138 
3139                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
3140                 cur_end = min(extent_map_end(em) - 1, end);
3141                 iosize = ALIGN(iosize, blocksize);
3142                 if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
3143                         disk_io_size = em->block_len;
3144                         offset = em->block_start;
3145                 } else {
3146                         offset = em->block_start + extent_offset;
3147                         disk_io_size = iosize;
3148                 }
3149                 bdev = em->bdev;
3150                 block_start = em->block_start;
3151                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
3152                         block_start = EXTENT_MAP_HOLE;
3153 
3154                 /*
3155                  * If we have a file range that points to a compressed extent
3156                  * and it's followed by a consecutive file range that points to
3157                  * to the same compressed extent (possibly with a different
3158                  * offset and/or length, so it either points to the whole extent
3159                  * or only part of it), we must make sure we do not submit a
3160                  * single bio to populate the pages for the 2 ranges because
3161                  * this makes the compressed extent read zero out the pages
3162                  * belonging to the 2nd range. Imagine the following scenario:
3163                  *
3164                  *  File layout
3165                  *  [0 - 8K]                     [8K - 24K]
3166                  *    |                               |
3167                  *    |                               |
3168                  * points to extent X,         points to extent X,
3169                  * offset 4K, length of 8K     offset 0, length 16K
3170                  *
3171                  * [extent X, compressed length = 4K uncompressed length = 16K]
3172                  *
3173                  * If the bio to read the compressed extent covers both ranges,
3174                  * it will decompress extent X into the pages belonging to the
3175                  * first range and then it will stop, zeroing out the remaining
3176                  * pages that belong to the other range that points to extent X.
3177                  * So here we make sure we submit 2 bios, one for the first
3178                  * range and another one for the third range. Both will target
3179                  * the same physical extent from disk, but we can't currently
3180                  * make the compressed bio endio callback populate the pages
3181                  * for both ranges because each compressed bio is tightly
3182                  * coupled with a single extent map, and each range can have
3183                  * an extent map with a different offset value relative to the
3184                  * uncompressed data of our extent and different lengths. This
3185                  * is a corner case so we prioritize correctness over
3186                  * non-optimal behavior (submitting 2 bios for the same extent).
3187                  */
3188                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) &&
3189                     prev_em_start && *prev_em_start != (u64)-1 &&
3190                     *prev_em_start != em->start)
3191                         force_bio_submit = true;
3192 
3193                 if (prev_em_start)
3194                         *prev_em_start = em->start;
3195 
3196                 free_extent_map(em);
3197                 em = NULL;
3198 
3199                 /* we've found a hole, just zero and go on */
3200                 if (block_start == EXTENT_MAP_HOLE) {
3201                         char *userpage;
3202                         struct extent_state *cached = NULL;
3203 
3204                         userpage = kmap_atomic(page);
3205                         memset(userpage + pg_offset, 0, iosize);
3206                         flush_dcache_page(page);
3207                         kunmap_atomic(userpage);
3208 
3209                         set_extent_uptodate(tree, cur, cur + iosize - 1,
3210                                             &cached, GFP_NOFS);
3211                         unlock_extent_cached(tree, cur,
3212                                              cur + iosize - 1, &cached);
3213                         cur = cur + iosize;
3214                         pg_offset += iosize;
3215                         continue;
3216                 }
3217                 /* the get_extent function already copied into the page */
3218                 if (test_range_bit(tree, cur, cur_end,
3219                                    EXTENT_UPTODATE, 1, NULL)) {
3220                         check_page_uptodate(tree, page);
3221                         unlock_extent(tree, cur, cur + iosize - 1);
3222                         cur = cur + iosize;
3223                         pg_offset += iosize;
3224                         continue;
3225                 }
3226                 /* we have an inline extent but it didn't get marked up
3227                  * to date.  Error out
3228                  */
3229                 if (block_start == EXTENT_MAP_INLINE) {
3230                         SetPageError(page);
3231                         unlock_extent(tree, cur, cur + iosize - 1);
3232                         cur = cur + iosize;
3233                         pg_offset += iosize;
3234                         continue;
3235                 }
3236 
3237                 ret = submit_extent_page(REQ_OP_READ | read_flags, tree, NULL,
3238                                          page, offset, disk_io_size,
3239                                          pg_offset, bdev, bio,
3240                                          end_bio_extent_readpage, mirror_num,
3241                                          *bio_flags,
3242                                          this_bio_flag,
3243                                          force_bio_submit);
3244                 if (!ret) {
3245                         nr++;
3246                         *bio_flags = this_bio_flag;
3247                 } else {
3248                         SetPageError(page);
3249                         unlock_extent(tree, cur, cur + iosize - 1);
3250                         goto out;
3251                 }
3252                 cur = cur + iosize;
3253                 pg_offset += iosize;
3254         }
3255 out:
3256         if (!nr) {
3257                 if (!PageError(page))
3258                         SetPageUptodate(page);
3259                 unlock_page(page);
3260         }
3261         return ret;
3262 }
3263 
3264 static inline void contiguous_readpages(struct extent_io_tree *tree,
3265                                              struct page *pages[], int nr_pages,
3266                                              u64 start, u64 end,
3267                                              struct extent_map **em_cached,
3268                                              struct bio **bio,
3269                                              unsigned long *bio_flags,
3270                                              u64 *prev_em_start)
3271 {
3272         struct btrfs_inode *inode = BTRFS_I(pages[0]->mapping->host);
3273         int index;
3274 
3275         btrfs_lock_and_flush_ordered_range(tree, inode, start, end, NULL);
3276 
3277         for (index = 0; index < nr_pages; index++) {
3278                 __do_readpage(tree, pages[index], btrfs_get_extent, em_cached,
3279                                 bio, 0, bio_flags, REQ_RAHEAD, prev_em_start);
3280                 put_page(pages[index]);
3281         }
3282 }
3283 
3284 static int __extent_read_full_page(struct extent_io_tree *tree,
3285                                    struct page *page,
3286                                    get_extent_t *get_extent,
3287                                    struct bio **bio, int mirror_num,
3288                                    unsigned long *bio_flags,
3289                                    unsigned int read_flags)
3290 {
3291         struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
3292         u64 start = page_offset(page);
3293         u64 end = start + PAGE_SIZE - 1;
3294         int ret;
3295 
3296         btrfs_lock_and_flush_ordered_range(tree, inode, start, end, NULL);
3297 
3298         ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
3299                             bio_flags, read_flags, NULL);
3300         return ret;
3301 }
3302 
3303 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
3304                             get_extent_t *get_extent, int mirror_num)
3305 {
3306         struct bio *bio = NULL;
3307         unsigned long bio_flags = 0;
3308         int ret;
3309 
3310         ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
3311                                       &bio_flags, 0);
3312         if (bio)
3313                 ret = submit_one_bio(bio, mirror_num, bio_flags);
3314         return ret;
3315 }
3316 
3317 static void update_nr_written(struct writeback_control *wbc,
3318                               unsigned long nr_written)
3319 {
3320         wbc->nr_to_write -= nr_written;
3321 }
3322 
3323 /*
3324  * helper for __extent_writepage, doing all of the delayed allocation setup.
3325  *
3326  * This returns 1 if btrfs_run_delalloc_range function did all the work required
3327  * to write the page (copy into inline extent).  In this case the IO has
3328  * been started and the page is already unlocked.
3329  *
3330  * This returns 0 if all went well (page still locked)
3331  * This returns < 0 if there were errors (page still locked)
3332  */
3333 static noinline_for_stack int writepage_delalloc(struct inode *inode,
3334                 struct page *page, struct writeback_control *wbc,
3335                 u64 delalloc_start, unsigned long *nr_written)
3336 {
3337         u64 page_end = delalloc_start + PAGE_SIZE - 1;
3338         bool found;
3339         u64 delalloc_to_write = 0;
3340         u64 delalloc_end = 0;
3341         int ret;
3342         int page_started = 0;
3343 
3344 
3345         while (delalloc_end < page_end) {
3346                 found = find_lock_delalloc_range(inode, page,
3347                                                &delalloc_start,
3348                                                &delalloc_end);
3349                 if (!found) {
3350                         delalloc_start = delalloc_end + 1;
3351                         continue;
3352                 }
3353                 ret = btrfs_run_delalloc_range(inode, page, delalloc_start,
3354                                 delalloc_end, &page_started, nr_written, wbc);
3355                 if (ret) {
3356                         SetPageError(page);
3357                         /*
3358                          * btrfs_run_delalloc_range should return < 0 for error
3359                          * but just in case, we use > 0 here meaning the IO is
3360                          * started, so we don't want to return > 0 unless
3361                          * things are going well.
3362                          */
3363                         ret = ret < 0 ? ret : -EIO;
3364                         goto done;
3365                 }
3366                 /*
3367                  * delalloc_end is already one less than the total length, so
3368                  * we don't subtract one from PAGE_SIZE
3369                  */
3370                 delalloc_to_write += (delalloc_end - delalloc_start +
3371                                       PAGE_SIZE) >> PAGE_SHIFT;
3372                 delalloc_start = delalloc_end + 1;
3373         }
3374         if (wbc->nr_to_write < delalloc_to_write) {
3375                 int thresh = 8192;
3376 
3377                 if (delalloc_to_write < thresh * 2)
3378                         thresh = delalloc_to_write;
3379                 wbc->nr_to_write = min_t(u64, delalloc_to_write,
3380                                          thresh);
3381         }
3382 
3383         /* did the fill delalloc function already unlock and start
3384          * the IO?
3385          */
3386         if (page_started) {
3387                 /*
3388                  * we've unlocked the page, so we can't update
3389                  * the mapping's writeback index, just update
3390                  * nr_to_write.
3391                  */
3392                 wbc->nr_to_write -= *nr_written;
3393                 return 1;
3394         }
3395 
3396         ret = 0;
3397 
3398 done:
3399         return ret;
3400 }
3401 
3402 /*
3403  * helper for __extent_writepage.  This calls the writepage start hooks,
3404  * and does the loop to map the page into extents and bios.
3405  *
3406  * We return 1 if the IO is started and the page is unlocked,
3407  * 0 if all went well (page still locked)
3408  * < 0 if there were errors (page still locked)
3409  */
3410 static noinline_for_stack int __extent_writepage_io(struct inode *inode,
3411                                  struct page *page,
3412                                  struct writeback_control *wbc,
3413                                  struct extent_page_data *epd,
3414                                  loff_t i_size,
3415                                  unsigned long nr_written,
3416                                  unsigned int write_flags, int *nr_ret)
3417 {
3418         struct extent_io_tree *tree = epd->tree;
3419         u64 start = page_offset(page);
3420         u64 page_end = start + PAGE_SIZE - 1;
3421         u64 end;
3422         u64 cur = start;
3423         u64 extent_offset;
3424         u64 block_start;
3425         u64 iosize;
3426         struct extent_map *em;
3427         struct block_device *bdev;
3428         size_t pg_offset = 0;
3429         size_t blocksize;
3430         int ret = 0;
3431         int nr = 0;
3432         bool compressed;
3433 
3434         ret = btrfs_writepage_cow_fixup(page, start, page_end);
3435         if (ret) {
3436                 /* Fixup worker will requeue */
3437                 if (ret == -EBUSY)
3438                         wbc->pages_skipped++;
3439                 else
3440                         redirty_page_for_writepage(wbc, page);
3441 
3442                 update_nr_written(wbc, nr_written);
3443                 unlock_page(page);
3444                 return 1;
3445         }
3446 
3447         /*
3448          * we don't want to touch the inode after unlocking the page,
3449          * so we update the mapping writeback index now
3450          */
3451         update_nr_written(wbc, nr_written + 1);
3452 
3453         end = page_end;
3454         if (i_size <= start) {
3455                 btrfs_writepage_endio_finish_ordered(page, start, page_end, 1);
3456                 goto done;
3457         }
3458 
3459         blocksize = inode->i_sb->s_blocksize;
3460 
3461         while (cur <= end) {
3462                 u64 em_end;
3463                 u64 offset;
3464 
3465                 if (cur >= i_size) {
3466                         btrfs_writepage_endio_finish_ordered(page, cur,
3467                                                              page_end, 1);
3468                         break;
3469                 }
3470                 em = btrfs_get_extent(BTRFS_I(inode), page, pg_offset, cur,
3471                                      end - cur + 1, 1);
3472                 if (IS_ERR_OR_NULL(em)) {
3473                         SetPageError(page);
3474                         ret = PTR_ERR_OR_ZERO(em);
3475                         break;
3476                 }
3477 
3478                 extent_offset = cur - em->start;
3479                 em_end = extent_map_end(em);
3480                 BUG_ON(em_end <= cur);
3481                 BUG_ON(end < cur);
3482                 iosize = min(em_end - cur, end - cur + 1);
3483                 iosize = ALIGN(iosize, blocksize);
3484                 offset = em->block_start + extent_offset;
3485                 bdev = em->bdev;
3486                 block_start = em->block_start;
3487                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
3488                 free_extent_map(em);
3489                 em = NULL;
3490 
3491                 /*
3492                  * compressed and inline extents are written through other
3493                  * paths in the FS
3494                  */
3495                 if (compressed || block_start == EXTENT_MAP_HOLE ||
3496                     block_start == EXTENT_MAP_INLINE) {
3497                         /*
3498                          * end_io notification does not happen here for
3499                          * compressed extents
3500                          */
3501                         if (!compressed)
3502                                 btrfs_writepage_endio_finish_ordered(page, cur,
3503                                                             cur + iosize - 1,
3504                                                             1);
3505                         else if (compressed) {
3506                                 /* we don't want to end_page_writeback on
3507                                  * a compressed extent.  this happens
3508                                  * elsewhere
3509                                  */
3510                                 nr++;
3511                         }
3512 
3513                         cur += iosize;
3514                         pg_offset += iosize;
3515                         continue;
3516                 }
3517 
3518                 btrfs_set_range_writeback(tree, cur, cur + iosize - 1);
3519                 if (!PageWriteback(page)) {
3520                         btrfs_err(BTRFS_I(inode)->root->fs_info,
3521                                    "page %lu not writeback, cur %llu end %llu",
3522                                page->index, cur, end);
3523                 }
3524 
3525                 ret = submit_extent_page(REQ_OP_WRITE | write_flags, tree, wbc,
3526                                          page, offset, iosize, pg_offset,
3527                                          bdev, &epd->bio,
3528                                          end_bio_extent_writepage,
3529                                          0, 0, 0, false);
3530                 if (ret) {
3531                         SetPageError(page);
3532                         if (PageWriteback(page))
3533                                 end_page_writeback(page);
3534                 }
3535 
3536                 cur = cur + iosize;
3537                 pg_offset += iosize;
3538                 nr++;
3539         }
3540 done:
3541         *nr_ret = nr;
3542         return ret;
3543 }
3544 
3545 /*
3546  * the writepage semantics are similar to regular writepage.  extent
3547  * records are inserted to lock ranges in the tree, and as dirty areas
3548  * are found, they are marked writeback.  Then the lock bits are removed
3549  * and the end_io handler clears the writeback ranges
3550  *
3551  * Return 0 if everything goes well.
3552  * Return <0 for error.
3553  */
3554 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
3555                               struct extent_page_data *epd)
3556 {
3557         struct inode *inode = page->mapping->host;
3558         u64 start = page_offset(page);
3559         u64 page_end = start + PAGE_SIZE - 1;
3560         int ret;
3561         int nr = 0;
3562         size_t pg_offset = 0;
3563         loff_t i_size = i_size_read(inode);
3564         unsigned long end_index = i_size >> PAGE_SHIFT;
3565         unsigned int write_flags = 0;
3566         unsigned long nr_written = 0;
3567 
3568         write_flags = wbc_to_write_flags(wbc);
3569 
3570         trace___extent_writepage(page, inode, wbc);
3571 
3572         WARN_ON(!PageLocked(page));
3573 
3574         ClearPageError(page);
3575 
3576         pg_offset = offset_in_page(i_size);
3577         if (page->index > end_index ||
3578            (page->index == end_index && !pg_offset)) {
3579                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
3580                 unlock_page(page);
3581                 return 0;
3582         }
3583 
3584         if (page->index == end_index) {
3585                 char *userpage;
3586 
3587                 userpage = kmap_atomic(page);
3588                 memset(userpage + pg_offset, 0,
3589                        PAGE_SIZE - pg_offset);
3590                 kunmap_atomic(userpage);
3591                 flush_dcache_page(page);
3592         }
3593 
3594         pg_offset = 0;
3595 
3596         set_page_extent_mapped(page);
3597 
3598         if (!epd->extent_locked) {
3599                 ret = writepage_delalloc(inode, page, wbc, start, &nr_written);
3600                 if (ret == 1)
3601                         goto done_unlocked;
3602                 if (ret)
3603                         goto done;
3604         }
3605 
3606         ret = __extent_writepage_io(inode, page, wbc, epd,
3607                                     i_size, nr_written, write_flags, &nr);
3608         if (ret == 1)
3609                 goto done_unlocked;
3610 
3611 done:
3612         if (nr == 0) {
3613                 /* make sure the mapping tag for page dirty gets cleared */
3614                 set_page_writeback(page);
3615                 end_page_writeback(page);
3616         }
3617         if (PageError(page)) {
3618                 ret = ret < 0 ? ret : -EIO;
3619                 end_extent_writepage(page, ret, start, page_end);
3620         }
3621         unlock_page(page);
3622         ASSERT(ret <= 0);
3623         return ret;
3624 
3625 done_unlocked:
3626         return 0;
3627 }
3628 
3629 void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
3630 {
3631         wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
3632                        TASK_UNINTERRUPTIBLE);
3633 }
3634 
3635 static void end_extent_buffer_writeback(struct extent_buffer *eb)
3636 {
3637         clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3638         smp_mb__after_atomic();
3639         wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
3640 }
3641 
3642 /*
3643  * Lock eb pages and flush the bio if we can't the locks
3644  *
3645  * Return  0 if nothing went wrong
3646  * Return >0 is same as 0, except bio is not submitted
3647  * Return <0 if something went wrong, no page is locked
3648  */
3649 static noinline_for_stack int lock_extent_buffer_for_io(struct extent_buffer *eb,
3650                           struct extent_page_data *epd)
3651 {
3652         struct btrfs_fs_info *fs_info = eb->fs_info;
3653         int i, num_pages, failed_page_nr;
3654         int flush = 0;
3655         int ret = 0;
3656 
3657         if (!btrfs_try_tree_write_lock(eb)) {
3658                 ret = flush_write_bio(epd);
3659                 if (ret < 0)
3660                         return ret;
3661                 flush = 1;
3662                 btrfs_tree_lock(eb);
3663         }
3664 
3665         if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
3666                 btrfs_tree_unlock(eb);
3667                 if (!epd->sync_io)
3668                         return 0;
3669                 if (!flush) {
3670                         ret = flush_write_bio(epd);
3671                         if (ret < 0)
3672                                 return ret;
3673                         flush = 1;
3674                 }
3675                 while (1) {
3676                         wait_on_extent_buffer_writeback(eb);
3677                         btrfs_tree_lock(eb);
3678                         if (!test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags))
3679                                 break;
3680                         btrfs_tree_unlock(eb);
3681                 }
3682         }
3683 
3684         /*
3685          * We need to do this to prevent races in people who check if the eb is
3686          * under IO since we can end up having no IO bits set for a short period
3687          * of time.
3688          */
3689         spin_lock(&eb->refs_lock);
3690         if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3691                 set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3692                 spin_unlock(&eb->refs_lock);
3693                 btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
3694                 percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
3695                                          -eb->len,
3696                                          fs_info->dirty_metadata_batch);
3697                 ret = 1;
3698         } else {
3699                 spin_unlock(&eb->refs_lock);
3700         }
3701 
3702         btrfs_tree_unlock(eb);
3703 
3704         if (!ret)
3705                 return ret;
3706 
3707         num_pages = num_extent_pages(eb);
3708         for (i = 0; i < num_pages; i++) {
3709                 struct page *p = eb->pages[i];
3710 
3711                 if (!trylock_page(p)) {
3712                         if (!flush) {
3713                                 int err;
3714 
3715                                 err = flush_write_bio(epd);
3716                                 if (err < 0) {
3717                                         ret = err;
3718                                         failed_page_nr = i;
3719                                         goto err_unlock;
3720                                 }
3721                                 flush = 1;
3722                         }
3723                         lock_page(p);
3724                 }
3725         }
3726 
3727         return ret;
3728 err_unlock:
3729         /* Unlock already locked pages */
3730         for (i = 0; i < failed_page_nr; i++)
3731                 unlock_page(eb->pages[i]);
3732         /*
3733          * Clear EXTENT_BUFFER_WRITEBACK and wake up anyone waiting on it.
3734          * Also set back EXTENT_BUFFER_DIRTY so future attempts to this eb can
3735          * be made and undo everything done before.
3736          */
3737         btrfs_tree_lock(eb);
3738         spin_lock(&eb->refs_lock);
3739         set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
3740         end_extent_buffer_writeback(eb);
3741         spin_unlock(&eb->refs_lock);
3742         percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, eb->len,
3743                                  fs_info->dirty_metadata_batch);
3744         btrfs_clear_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
3745         btrfs_tree_unlock(eb);
3746         return ret;
3747 }
3748 
3749 static void set_btree_ioerr(struct page *page)
3750 {
3751         struct extent_buffer *eb = (struct extent_buffer *)page->private;
3752         struct btrfs_fs_info *fs_info;
3753 
3754         SetPageError(page);
3755         if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
3756                 return;
3757 
3758         /*
3759          * If we error out, we should add back the dirty_metadata_bytes
3760          * to make it consistent.
3761          */
3762         fs_info = eb->fs_info;
3763         percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
3764                                  eb->len, fs_info->dirty_metadata_batch);
3765 
3766         /*
3767          * If writeback for a btree extent that doesn't belong to a log tree
3768          * failed, increment the counter transaction->eb_write_errors.
3769          * We do this because while the transaction is running and before it's
3770          * committing (when we call filemap_fdata[write|wait]_range against
3771          * the btree inode), we might have
3772          * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
3773          * returns an error or an error happens during writeback, when we're
3774          * committing the transaction we wouldn't know about it, since the pages
3775          * can be no longer dirty nor marked anymore for writeback (if a
3776          * subsequent modification to the extent buffer didn't happen before the
3777          * transaction commit), which makes filemap_fdata[write|wait]_range not
3778          * able to find the pages tagged with SetPageError at transaction
3779          * commit time. So if this happens we must abort the transaction,
3780          * otherwise we commit a super block with btree roots that point to
3781          * btree nodes/leafs whose content on disk is invalid - either garbage
3782          * or the content of some node/leaf from a past generation that got
3783          * cowed or deleted and is no longer valid.
3784          *
3785          * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
3786          * not be enough - we need to distinguish between log tree extents vs
3787          * non-log tree extents, and the next filemap_fdatawait_range() call
3788          * will catch and clear such errors in the mapping - and that call might
3789          * be from a log sync and not from a transaction commit. Also, checking
3790          * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
3791          * not done and would not be reliable - the eb might have been released
3792          * from memory and reading it back again means that flag would not be
3793          * set (since it's a runtime flag, not persisted on disk).
3794          *
3795          * Using the flags below in the btree inode also makes us achieve the
3796          * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
3797          * writeback for all dirty pages and before filemap_fdatawait_range()
3798          * is called, the writeback for all dirty pages had already finished
3799          * with errors - because we were not using AS_EIO/AS_ENOSPC,
3800          * filemap_fdatawait_range() would return success, as it could not know
3801          * that writeback errors happened (the pages were no longer tagged for
3802          * writeback).
3803          */
3804         switch (eb->log_index) {
3805         case -1:
3806                 set_bit(BTRFS_FS_BTREE_ERR, &eb->fs_info->flags);
3807                 break;
3808         case 0:
3809                 set_bit(BTRFS_FS_LOG1_ERR, &eb->fs_info->flags);
3810                 break;
3811         case 1:
3812                 set_bit(BTRFS_FS_LOG2_ERR, &eb->fs_info->flags);
3813                 break;
3814         default:
3815                 BUG(); /* unexpected, logic error */
3816         }
3817 }
3818 
3819 static void end_bio_extent_buffer_writepage(struct bio *bio)
3820 {
3821         struct bio_vec *bvec;
3822         struct extent_buffer *eb;
3823         int done;
3824         struct bvec_iter_all iter_all;
3825 
3826         ASSERT(!bio_flagged(bio, BIO_CLONED));
3827         bio_for_each_segment_all(bvec, bio, iter_all) {
3828                 struct page *page = bvec->bv_page;
3829 
3830                 eb = (struct extent_buffer *)page->private;
3831                 BUG_ON(!eb);
3832                 done = atomic_dec_and_test(&eb->io_pages);
3833 
3834                 if (bio->bi_status ||
3835                     test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
3836                         ClearPageUptodate(page);
3837                         set_btree_ioerr(page);
3838                 }
3839 
3840                 end_page_writeback(page);
3841 
3842                 if (!done)
3843                         continue;
3844 
3845                 end_extent_buffer_writeback(eb);
3846         }
3847 
3848         bio_put(bio);
3849 }
3850 
3851 static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
3852                         struct writeback_control *wbc,
3853                         struct extent_page_data *epd)
3854 {
3855         struct btrfs_fs_info *fs_info = eb->fs_info;
3856         struct block_device *bdev = fs_info->fs_devices->latest_bdev;
3857         struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
3858         u64 offset = eb->start;
3859         u32 nritems;
3860         int i, num_pages;
3861         unsigned long start, end;
3862         unsigned int write_flags = wbc_to_write_flags(wbc) | REQ_META;
3863         int ret = 0;
3864 
3865         clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
3866         num_pages = num_extent_pages(eb);
3867         atomic_set(&eb->io_pages, num_pages);
3868 
3869         /* set btree blocks beyond nritems with 0 to avoid stale content. */
3870         nritems = btrfs_header_nritems(eb);
3871         if (btrfs_header_level(eb) > 0) {
3872                 end = btrfs_node_key_ptr_offset(nritems);
3873 
3874                 memzero_extent_buffer(eb, end, eb->len - end);
3875         } else {
3876                 /*
3877                  * leaf:
3878                  * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0
3879                  */
3880                 start = btrfs_item_nr_offset(nritems);
3881                 end = BTRFS_LEAF_DATA_OFFSET + leaf_data_end(eb);
3882                 memzero_extent_buffer(eb, start, end - start);
3883         }
3884 
3885         for (i = 0; i < num_pages; i++) {
3886                 struct page *p = eb->pages[i];
3887 
3888                 clear_page_dirty_for_io(p);
3889                 set_page_writeback(p);
3890                 ret = submit_extent_page(REQ_OP_WRITE | write_flags, tree, wbc,
3891                                          p, offset, PAGE_SIZE, 0, bdev,
3892                                          &epd->bio,
3893                                          end_bio_extent_buffer_writepage,
3894                                          0, 0, 0, false);
3895                 if (ret) {
3896                         set_btree_ioerr(p);
3897                         if (PageWriteback(p))
3898                                 end_page_writeback(p);
3899                         if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
3900                                 end_extent_buffer_writeback(eb);
3901                         ret = -EIO;
3902                         break;
3903                 }
3904                 offset += PAGE_SIZE;
3905                 update_nr_written(wbc, 1);
3906                 unlock_page(p);
3907         }
3908 
3909         if (unlikely(ret)) {
3910                 for (; i < num_pages; i++) {
3911                         struct page *p = eb->pages[i];
3912                         clear_page_dirty_for_io(p);
3913                         unlock_page(p);
3914                 }
3915         }
3916 
3917         return ret;
3918 }
3919 
3920 int btree_write_cache_pages(struct address_space *mapping,
3921                                    struct writeback_control *wbc)
3922 {
3923         struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
3924         struct extent_buffer *eb, *prev_eb = NULL;
3925         struct extent_page_data epd = {
3926                 .bio = NULL,
3927                 .tree = tree,
3928                 .extent_locked = 0,
3929                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
3930         };
3931         struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
3932         int ret = 0;
3933         int done = 0;
3934         int nr_to_write_done = 0;
3935         struct pagevec pvec;
3936         int nr_pages;
3937         pgoff_t index;
3938         pgoff_t end;            /* Inclusive */
3939         int scanned = 0;
3940         xa_mark_t tag;
3941 
3942         pagevec_init(&pvec);
3943         if (wbc->range_cyclic) {
3944                 index = mapping->writeback_index; /* Start from prev offset */
3945                 end = -1;
3946                 /*
3947                  * Start from the beginning does not need to cycle over the
3948                  * range, mark it as scanned.
3949                  */
3950                 scanned = (index == 0);
3951         } else {
3952                 index = wbc->range_start >> PAGE_SHIFT;
3953                 end = wbc->range_end >> PAGE_SHIFT;
3954                 scanned = 1;
3955         }
3956         if (wbc->sync_mode == WB_SYNC_ALL)
3957                 tag = PAGECACHE_TAG_TOWRITE;
3958         else
3959                 tag = PAGECACHE_TAG_DIRTY;
3960 retry:
3961         if (wbc->sync_mode == WB_SYNC_ALL)
3962                 tag_pages_for_writeback(mapping, index, end);
3963         while (!done && !nr_to_write_done && (index <= end) &&
3964                (nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
3965                         tag))) {
3966                 unsigned i;
3967 
3968                 for (i = 0; i < nr_pages; i++) {
3969                         struct page *page = pvec.pages[i];
3970 
3971                         if (!PagePrivate(page))
3972                                 continue;
3973 
3974                         spin_lock(&mapping->private_lock);
3975                         if (!PagePrivate(page)) {
3976                                 spin_unlock(&mapping->private_lock);
3977                                 continue;
3978                         }
3979 
3980                         eb = (struct extent_buffer *)page->private;
3981 
3982                         /*
3983                          * Shouldn't happen and normally this would be a BUG_ON
3984                          * but no sense in crashing the users box for something
3985                          * we can survive anyway.
3986                          */
3987                         if (WARN_ON(!eb)) {
3988                                 spin_unlock(&mapping->private_lock);
3989                                 continue;
3990                         }
3991 
3992                         if (eb == prev_eb) {
3993                                 spin_unlock(&mapping->private_lock);
3994                                 continue;
3995                         }
3996 
3997                         ret = atomic_inc_not_zero(&eb->refs);
3998                         spin_unlock(&mapping->private_lock);
3999                         if (!ret)
4000                                 continue;
4001 
4002                         prev_eb = eb;
4003                         ret = lock_extent_buffer_for_io(eb, &epd);
4004                         if (!ret) {
4005                                 free_extent_buffer(eb);
4006                                 continue;
4007                         } else if (ret < 0) {
4008                                 done = 1;
4009                                 free_extent_buffer(eb);
4010                                 break;
4011                         }
4012 
4013                         ret = write_one_eb(eb, wbc, &epd);
4014                         if (ret) {
4015                                 done = 1;
4016                                 free_extent_buffer(eb);
4017                                 break;
4018                         }
4019                         free_extent_buffer(eb);
4020 
4021                         /*
4022                          * the filesystem may choose to bump up nr_to_write.
4023                          * We have to make sure to honor the new nr_to_write
4024                          * at any time
4025                          */
4026                         nr_to_write_done = wbc->nr_to_write <= 0;
4027                 }
4028                 pagevec_release(&pvec);
4029                 cond_resched();
4030         }
4031         if (!scanned && !done) {
4032                 /*
4033                  * We hit the last page and there is more work to be done: wrap
4034                  * back to the start of the file
4035                  */
4036                 scanned = 1;
4037                 index = 0;
4038                 goto retry;
4039         }
4040         ASSERT(ret <= 0);
4041         if (ret < 0) {
4042                 end_write_bio(&epd, ret);
4043                 return ret;
4044         }
4045         /*
4046          * If something went wrong, don't allow any metadata write bio to be
4047          * submitted.
4048          *
4049          * This would prevent use-after-free if we had dirty pages not
4050          * cleaned up, which can still happen by fuzzed images.
4051          *
4052          * - Bad extent tree
4053          *   Allowing existing tree block to be allocated for other trees.
4054          *
4055          * - Log tree operations
4056          *   Exiting tree blocks get allocated to log tree, bumps its
4057          *   generation, then get cleaned in tree re-balance.
4058          *   Such tree block will not be written back, since it's clean,
4059          *   thus no WRITTEN flag set.
4060          *   And after log writes back, this tree block is not traced by
4061          *   any dirty extent_io_tree.
4062          *
4063          * - Offending tree block gets re-dirtied from its original owner
4064          *   Since it has bumped generation, no WRITTEN flag, it can be
4065          *   reused without COWing. This tree block will not be traced
4066          *   by btrfs_transaction::dirty_pages.
4067          *
4068          *   Now such dirty tree block will not be cleaned by any dirty
4069          *   extent io tree. Thus we don't want to submit such wild eb
4070          *   if the fs already has error.
4071          */
4072         if (!test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
4073                 ret = flush_write_bio(&epd);
4074         } else {
4075                 ret = -EUCLEAN;
4076                 end_write_bio(&epd, ret);
4077         }
4078         return ret;
4079 }
4080 
4081 /**
4082  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
4083  * @mapping: address space structure to write
4084  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
4085  * @data: data passed to __extent_writepage function
4086  *
4087  * If a page is already under I/O, write_cache_pages() skips it, even
4088  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
4089  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
4090  * and msync() need to guarantee that all the data which was dirty at the time
4091  * the call was made get new I/O started against them.  If wbc->sync_mode is
4092  * WB_SYNC_ALL then we were called for data integrity and we must wait for
4093  * existing IO to complete.
4094  */
4095 static int extent_write_cache_pages(struct address_space *mapping,
4096                              struct writeback_control *wbc,
4097                              struct extent_page_data *epd)
4098 {
4099         struct inode *inode = mapping->host;
4100         int ret = 0;
4101         int done = 0;
4102         int nr_to_write_done = 0;
4103         struct pagevec pvec;
4104         int nr_pages;
4105         pgoff_t index;
4106         pgoff_t end;            /* Inclusive */
4107         pgoff_t done_index;
4108         int range_whole = 0;
4109         int scanned = 0;
4110         xa_mark_t tag;
4111 
4112         /*
4113          * We have to hold onto the inode so that ordered extents can do their
4114          * work when the IO finishes.  The alternative to this is failing to add
4115          * an ordered extent if the igrab() fails there and that is a huge pain
4116          * to deal with, so instead just hold onto the inode throughout the
4117          * writepages operation.  If it fails here we are freeing up the inode
4118          * anyway and we'd rather not waste our time writing out stuff that is
4119          * going to be truncated anyway.
4120          */
4121         if (!igrab(inode))
4122                 return 0;
4123 
4124         pagevec_init(&pvec);
4125         if (wbc->range_cyclic) {
4126                 index = mapping->writeback_index; /* Start from prev offset */
4127                 end = -1;
4128                 /*
4129                  * Start from the beginning does not need to cycle over the
4130                  * range, mark it as scanned.
4131                  */
4132                 scanned = (index == 0);
4133         } else {
4134                 index = wbc->range_start >> PAGE_SHIFT;
4135                 end = wbc->range_end >> PAGE_SHIFT;
4136                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
4137                         range_whole = 1;
4138                 scanned = 1;
4139         }
4140 
4141         /*
4142          * We do the tagged writepage as long as the snapshot flush bit is set
4143          * and we are the first one who do the filemap_flush() on this inode.
4144          *
4145          * The nr_to_write == LONG_MAX is needed to make sure other flushers do
4146          * not race in and drop the bit.
4147          */
4148         if (range_whole && wbc->nr_to_write == LONG_MAX &&
4149             test_and_clear_bit(BTRFS_INODE_SNAPSHOT_FLUSH,
4150                                &BTRFS_I(inode)->runtime_flags))
4151                 wbc->tagged_writepages = 1;
4152 
4153         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
4154                 tag = PAGECACHE_TAG_TOWRITE;
4155         else
4156                 tag = PAGECACHE_TAG_DIRTY;
4157 retry:
4158         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
4159                 tag_pages_for_writeback(mapping, index, end);
4160         done_index = index;
4161         while (!done && !nr_to_write_done && (index <= end) &&
4162                         (nr_pages = pagevec_lookup_range_tag(&pvec, mapping,
4163                                                 &index, end, tag))) {
4164                 unsigned i;
4165 
4166                 for (i = 0; i < nr_pages; i++) {
4167                         struct page *page = pvec.pages[i];
4168 
4169                         done_index = page->index + 1;
4170                         /*
4171                          * At this point we hold neither the i_pages lock nor
4172                          * the page lock: the page may be truncated or
4173                          * invalidated (changing page->mapping to NULL),
4174                          * or even swizzled back from swapper_space to
4175                          * tmpfs file mapping
4176                          */
4177                         if (!trylock_page(page)) {
4178                                 ret = flush_write_bio(epd);
4179                                 BUG_ON(ret < 0);
4180                                 lock_page(page);
4181                         }
4182 
4183                         if (unlikely(page->mapping != mapping)) {
4184                                 unlock_page(page);
4185                                 continue;
4186                         }
4187 
4188                         if (wbc->sync_mode != WB_SYNC_NONE) {
4189                                 if (PageWriteback(page)) {
4190                                         ret = flush_write_bio(epd);
4191                                         BUG_ON(ret < 0);
4192                                 }
4193                                 wait_on_page_writeback(page);
4194                         }
4195 
4196                         if (PageWriteback(page) ||
4197                             !clear_page_dirty_for_io(page)) {
4198                                 unlock_page(page);
4199                                 continue;
4200                         }
4201 
4202                         ret = __extent_writepage(page, wbc, epd);
4203                         if (ret < 0) {
4204                                 done = 1;
4205                                 break;
4206                         }
4207 
4208                         /*
4209                          * the filesystem may choose to bump up nr_to_write.
4210                          * We have to make sure to honor the new nr_to_write
4211                          * at any time
4212                          */
4213                         nr_to_write_done = wbc->nr_to_write <= 0;
4214                 }
4215                 pagevec_release(&pvec);
4216                 cond_resched();
4217         }
4218         if (!scanned && !done) {
4219                 /*
4220                  * We hit the last page and there is more work to be done: wrap
4221                  * back to the start of the file
4222                  */
4223                 scanned = 1;
4224                 index = 0;
4225 
4226                 /*
4227                  * If we're looping we could run into a page that is locked by a
4228                  * writer and that writer could be waiting on writeback for a
4229                  * page in our current bio, and thus deadlock, so flush the
4230                  * write bio here.
4231                  */
4232                 ret = flush_write_bio(epd);
4233                 if (!ret)
4234                         goto retry;
4235         }
4236 
4237         if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole))
4238                 mapping->writeback_index = done_index;
4239 
4240         btrfs_add_delayed_iput(inode);
4241         return ret;
4242 }
4243 
4244 int extent_write_full_page(struct page *page, struct writeback_control *wbc)
4245 {
4246         int ret;
4247         struct extent_page_data epd = {
4248                 .bio = NULL,
4249                 .tree = &BTRFS_I(page->mapping->host)->io_tree,
4250                 .extent_locked = 0,
4251                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4252         };
4253 
4254         ret = __extent_writepage(page, wbc, &epd);
4255         ASSERT(ret <= 0);
4256         if (ret < 0) {
4257                 end_write_bio(&epd, ret);
4258                 return ret;
4259         }
4260 
4261         ret = flush_write_bio(&epd);
4262         ASSERT(ret <= 0);
4263         return ret;
4264 }
4265 
4266 int extent_write_locked_range(struct inode *inode, u64 start, u64 end,
4267                               int mode)
4268 {
4269         int ret = 0;
4270         struct address_space *mapping = inode->i_mapping;
4271         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
4272         struct page *page;
4273         unsigned long nr_pages = (end - start + PAGE_SIZE) >>
4274                 PAGE_SHIFT;
4275 
4276         struct extent_page_data epd = {
4277                 .bio = NULL,
4278                 .tree = tree,
4279                 .extent_locked = 1,
4280                 .sync_io = mode == WB_SYNC_ALL,
4281         };
4282         struct writeback_control wbc_writepages = {
4283                 .sync_mode      = mode,
4284                 .nr_to_write    = nr_pages * 2,
4285                 .range_start    = start,
4286                 .range_end      = end + 1,
4287         };
4288 
4289         while (start <= end) {
4290                 page = find_get_page(mapping, start >> PAGE_SHIFT);
4291                 if (clear_page_dirty_for_io(page))
4292                         ret = __extent_writepage(page, &wbc_writepages, &epd);
4293                 else {
4294                         btrfs_writepage_endio_finish_ordered(page, start,
4295                                                     start + PAGE_SIZE - 1, 1);
4296                         unlock_page(page);
4297                 }
4298                 put_page(page);
4299                 start += PAGE_SIZE;
4300         }
4301 
4302         ASSERT(ret <= 0);
4303         if (ret < 0) {
4304                 end_write_bio(&epd, ret);
4305                 return ret;
4306         }
4307         ret = flush_write_bio(&epd);
4308         return ret;
4309 }
4310 
4311 int extent_writepages(struct address_space *mapping,
4312                       struct writeback_control *wbc)
4313 {
4314         int ret = 0;
4315         struct extent_page_data epd = {
4316                 .bio = NULL,
4317                 .tree = &BTRFS_I(mapping->host)->io_tree,
4318                 .extent_locked = 0,
4319                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4320         };
4321 
4322         ret = extent_write_cache_pages(mapping, wbc, &epd);
4323         ASSERT(ret <= 0);
4324         if (ret < 0) {
4325                 end_write_bio(&epd, ret);
4326                 return ret;
4327         }
4328         ret = flush_write_bio(&epd);
4329         return ret;
4330 }
4331 
4332 int extent_readpages(struct address_space *mapping, struct list_head *pages,
4333                      unsigned nr_pages)
4334 {
4335         struct bio *bio = NULL;
4336         unsigned long bio_flags = 0;
4337         struct page *pagepool[16];
4338         struct extent_map *em_cached = NULL;
4339         struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
4340         int nr = 0;
4341         u64 prev_em_start = (u64)-1;
4342 
4343         while (!list_empty(pages)) {
4344                 u64 contig_end = 0;
4345 
4346                 for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) {
4347                         struct page *page = lru_to_page(pages);
4348 
4349                         prefetchw(&page->flags);
4350                         list_del(&page->lru);
4351                         if (add_to_page_cache_lru(page, mapping, page->index,
4352                                                 readahead_gfp_mask(mapping))) {
4353                                 put_page(page);
4354                                 break;
4355                         }
4356 
4357                         pagepool[nr++] = page;
4358                         contig_end = page_offset(page) + PAGE_SIZE - 1;
4359                 }
4360 
4361                 if (nr) {
4362                         u64 contig_start = page_offset(pagepool[0]);
4363 
4364                         ASSERT(contig_start + nr * PAGE_SIZE - 1 == contig_end);
4365 
4366                         contiguous_readpages(tree, pagepool, nr, contig_start,
4367                                      contig_end, &em_cached, &bio, &bio_flags,
4368                                      &prev_em_start);
4369                 }
4370         }
4371 
4372         if (em_cached)
4373                 free_extent_map(em_cached);
4374 
4375         if (bio)
4376                 return submit_one_bio(bio, 0, bio_flags);
4377         return 0;
4378 }
4379 
4380 /*
4381  * basic invalidatepage code, this waits on any locked or writeback
4382  * ranges corresponding to the page, and then deletes any extent state
4383  * records from the tree
4384  */
4385 int extent_invalidatepage(struct extent_io_tree *tree,
4386                           struct page *page, unsigned long offset)
4387 {
4388         struct extent_state *cached_state = NULL;
4389         u64 start = page_offset(page);
4390         u64 end = start + PAGE_SIZE - 1;
4391         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
4392 
4393         start += ALIGN(offset, blocksize);
4394         if (start > end)
4395                 return 0;
4396 
4397         lock_extent_bits(tree, start, end, &cached_state);
4398         wait_on_page_writeback(page);
4399         clear_extent_bit(tree, start, end, EXTENT_LOCKED | EXTENT_DELALLOC |
4400                          EXTENT_DO_ACCOUNTING, 1, 1, &cached_state);
4401         return 0;
4402 }
4403 
4404 /*
4405  * a helper for releasepage, this tests for areas of the page that
4406  * are locked or under IO and drops the related state bits if it is safe
4407  * to drop the page.
4408  */
4409 static int try_release_extent_state(struct extent_io_tree *tree,
4410                                     struct page *page, gfp_t mask)
4411 {
4412         u64 start = page_offset(page);
4413         u64 end = start + PAGE_SIZE - 1;
4414         int ret = 1;
4415 
4416         if (test_range_bit(tree, start, end, EXTENT_LOCKED, 0, NULL)) {
4417                 ret = 0;
4418         } else {
4419                 /*
4420                  * at this point we can safely clear everything except the
4421                  * locked bit and the nodatasum bit
4422                  */
4423                 ret = __clear_extent_bit(tree, start, end,
4424                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
4425                                  0, 0, NULL, mask, NULL);
4426 
4427                 /* if clear_extent_bit failed for enomem reasons,
4428                  * we can't allow the release to continue.
4429                  */
4430                 if (ret < 0)
4431                         ret = 0;
4432                 else
4433                         ret = 1;
4434         }
4435         return ret;
4436 }
4437 
4438 /*
4439  * a helper for releasepage.  As long as there are no locked extents
4440  * in the range corresponding to the page, both state records and extent
4441  * map records are removed
4442  */
4443 int try_release_extent_mapping(struct page *page, gfp_t mask)
4444 {
4445         struct extent_map *em;
4446         u64 start = page_offset(page);
4447         u64 end = start + PAGE_SIZE - 1;
4448         struct btrfs_inode *btrfs_inode = BTRFS_I(page->mapping->host);
4449         struct extent_io_tree *tree = &btrfs_inode->io_tree;
4450         struct extent_map_tree *map = &btrfs_inode->extent_tree;
4451 
4452         if (gfpflags_allow_blocking(mask) &&
4453             page->mapping->host->i_size > SZ_16M) {
4454                 u64 len;
4455                 while (start <= end) {
4456                         len = end - start + 1;
4457                         write_lock(&map->lock);
4458                         em = lookup_extent_mapping(map, start, len);
4459                         if (!em) {
4460                                 write_unlock(&map->lock);
4461                                 break;
4462                         }
4463                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
4464                             em->start != start) {
4465                                 write_unlock(&map->lock);
4466                                 free_extent_map(em);
4467                                 break;
4468                         }
4469                         if (!test_range_bit(tree, em->start,
4470                                             extent_map_end(em) - 1,
4471                                             EXTENT_LOCKED, 0, NULL)) {
4472                                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
4473                                         &btrfs_inode->runtime_flags);
4474                                 remove_extent_mapping(map, em);
4475                                 /* once for the rb tree */
4476                                 free_extent_map(em);
4477                         }
4478                         start = extent_map_end(em);
4479                         write_unlock(&map->lock);
4480 
4481                         /* once for us */
4482                         free_extent_map(em);
4483                 }
4484         }
4485         return try_release_extent_state(tree, page, mask);
4486 }
4487 
4488 /*
4489  * helper function for fiemap, which doesn't want to see any holes.
4490  * This maps until we find something past 'last'
4491  */
4492 static struct extent_map *get_extent_skip_holes(struct inode *inode,
4493                                                 u64 offset, u64 last)
4494 {
4495         u64 sectorsize = btrfs_inode_sectorsize(inode);
4496         struct extent_map *em;
4497         u64 len;
4498 
4499         if (offset >= last)
4500                 return NULL;
4501 
4502         while (1) {
4503                 len = last - offset;
4504                 if (len == 0)
4505                         break;
4506                 len = ALIGN(len, sectorsize);
4507                 em = btrfs_get_extent_fiemap(BTRFS_I(inode), offset, len);
4508                 if (IS_ERR_OR_NULL(em))
4509                         return em;
4510 
4511                 /* if this isn't a hole return it */
4512                 if (em->block_start != EXTENT_MAP_HOLE)
4513                         return em;
4514 
4515                 /* this is a hole, advance to the next extent */
4516                 offset = extent_map_end(em);
4517                 free_extent_map(em);
4518                 if (offset >= last)
4519                         break;
4520         }
4521         return NULL;
4522 }
4523 
4524 /*
4525  * To cache previous fiemap extent
4526  *
4527  * Will be used for merging fiemap extent
4528  */
4529 struct fiemap_cache {
4530         u64 offset;
4531         u64 phys;
4532         u64 len;
4533         u32 flags;
4534         bool cached;
4535 };
4536 
4537 /*
4538  * Helper to submit fiemap extent.
4539  *
4540  * Will try to merge current fiemap extent specified by @offset, @phys,
4541  * @len and @flags with cached one.
4542  * And only when we fails to merge, cached one will be submitted as
4543  * fiemap extent.
4544  *
4545  * Return value is the same as fiemap_fill_next_extent().
4546  */
4547 static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
4548                                 struct fiemap_cache *cache,
4549                                 u64 offset, u64 phys, u64 len, u32 flags)
4550 {
4551         int ret = 0;
4552 
4553         if (!cache->cached)
4554                 goto assign;
4555 
4556         /*
4557          * Sanity check, extent_fiemap() should have ensured that new
4558          * fiemap extent won't overlap with cached one.
4559          * Not recoverable.
4560          *
4561          * NOTE: Physical address can overlap, due to compression
4562          */
4563         if (cache->offset + cache->len > offset) {
4564                 WARN_ON(1);
4565                 return -EINVAL;
4566         }
4567 
4568         /*
4569          * Only merges fiemap extents if
4570          * 1) Their logical addresses are continuous
4571          *
4572          * 2) Their physical addresses are continuous
4573          *    So truly compressed (physical size smaller than logical size)
4574          *    extents won't get merged with each other
4575          *
4576          * 3) Share same flags except FIEMAP_EXTENT_LAST
4577          *    So regular extent won't get merged with prealloc extent
4578          */
4579         if (cache->offset + cache->len  == offset &&
4580             cache->phys + cache->len == phys  &&
4581             (cache->flags & ~FIEMAP_EXTENT_LAST) ==
4582                         (flags & ~FIEMAP_EXTENT_LAST)) {
4583                 cache->len += len;
4584                 cache->flags |= flags;
4585                 goto try_submit_last;
4586         }
4587 
4588         /* Not mergeable, need to submit cached one */
4589         ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
4590                                       cache->len, cache->flags);
4591         cache->cached = false;
4592         if (ret)
4593                 return ret;
4594 assign:
4595         cache->cached = true;
4596         cache->offset = offset;
4597         cache->phys = phys;
4598         cache->len = len;
4599         cache->flags = flags;
4600 try_submit_last:
4601         if (cache->flags & FIEMAP_EXTENT_LAST) {
4602                 ret = fiemap_fill_next_extent(fieinfo, cache->offset,
4603                                 cache->phys, cache->len, cache->flags);
4604                 cache->cached = false;
4605         }
4606         return ret;
4607 }
4608 
4609 /*
4610  * Emit last fiemap cache
4611  *
4612  * The last fiemap cache may still be cached in the following case:
4613  * 0                  4k                    8k
4614  * |<- Fiemap range ->|
4615  * |<------------  First extent ----------->|
4616  *
4617  * In this case, the first extent range will be cached but not emitted.
4618  * So we must emit it before ending extent_fiemap().
4619  */
4620 static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo,
4621                                   struct fiemap_cache *cache)
4622 {
4623         int ret;
4624 
4625         if (!cache->cached)
4626                 return 0;
4627 
4628         ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
4629                                       cache->len, cache->flags);
4630         cache->cached = false;
4631         if (ret > 0)
4632                 ret = 0;
4633         return ret;
4634 }
4635 
4636 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
4637                 __u64 start, __u64 len)
4638 {
4639         int ret = 0;
4640         u64 off = start;
4641         u64 max = start + len;
4642         u32 flags = 0;
4643         u32 found_type;
4644         u64 last;
4645         u64 last_for_get_extent = 0;
4646         u64 disko = 0;
4647         u64 isize = i_size_read(inode);
4648         struct btrfs_key found_key;
4649         struct extent_map *em = NULL;
4650         struct extent_state *cached_state = NULL;
4651         struct btrfs_path *path;
4652         struct btrfs_root *root = BTRFS_I(inode)->root;
4653         struct fiemap_cache cache = { 0 };
4654         struct ulist *roots;
4655         struct ulist *tmp_ulist;
4656         int end = 0;
4657         u64 em_start = 0;
4658         u64 em_len = 0;
4659         u64 em_end = 0;
4660 
4661         if (len == 0)
4662                 return -EINVAL;
4663 
4664         path = btrfs_alloc_path();
4665         if (!path)
4666                 return -ENOMEM;
4667         path->leave_spinning = 1;
4668 
4669         roots = ulist_alloc(GFP_KERNEL);
4670         tmp_ulist = ulist_alloc(GFP_KERNEL);
4671         if (!roots || !tmp_ulist) {
4672                 ret = -ENOMEM;
4673                 goto out_free_ulist;
4674         }
4675 
4676         start = round_down(start, btrfs_inode_sectorsize(inode));
4677         len = round_up(max, btrfs_inode_sectorsize(inode)) - start;
4678 
4679         /*
4680          * lookup the last file extent.  We're not using i_size here
4681          * because there might be preallocation past i_size
4682          */
4683         ret = btrfs_lookup_file_extent(NULL, root, path,
4684                         btrfs_ino(BTRFS_I(inode)), -1, 0);
4685         if (ret < 0) {
4686                 goto out_free_ulist;
4687         } else {
4688                 WARN_ON(!ret);
4689                 if (ret == 1)
4690                         ret = 0;
4691         }
4692 
4693         path->slots[0]--;
4694         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
4695         found_type = found_key.type;
4696 
4697         /* No extents, but there might be delalloc bits */
4698         if (found_key.objectid != btrfs_ino(BTRFS_I(inode)) ||
4699             found_type != BTRFS_EXTENT_DATA_KEY) {
4700                 /* have to trust i_size as the end */
4701                 last = (u64)-1;
4702                 last_for_get_extent = isize;
4703         } else {
4704                 /*
4705                  * remember the start of the last extent.  There are a
4706                  * bunch of different factors that go into the length of the
4707                  * extent, so its much less complex to remember where it started
4708                  */
4709                 last = found_key.offset;
4710                 last_for_get_extent = last + 1;
4711         }
4712         btrfs_release_path(path);
4713 
4714         /*
4715          * we might have some extents allocated but more delalloc past those
4716          * extents.  so, we trust isize unless the start of the last extent is
4717          * beyond isize
4718          */
4719         if (last < isize) {
4720                 last = (u64)-1;
4721                 last_for_get_extent = isize;
4722         }
4723 
4724         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4725                          &cached_state);
4726 
4727         em = get_extent_skip_holes(inode, start, last_for_get_extent);
4728         if (!em)
4729                 goto out;
4730         if (IS_ERR(em)) {
4731                 ret = PTR_ERR(em);
4732                 goto out;
4733         }
4734 
4735         while (!end) {
4736                 u64 offset_in_extent = 0;
4737 
4738                 /* break if the extent we found is outside the range */
4739                 if (em->start >= max || extent_map_end(em) < off)
4740                         break;
4741 
4742                 /*
4743                  * get_extent may return an extent that starts before our
4744                  * requested range.  We have to make sure the ranges
4745                  * we return to fiemap always move forward and don't
4746                  * overlap, so adjust the offsets here
4747                  */
4748                 em_start = max(em->start, off);
4749 
4750                 /*
4751                  * record the offset from the start of the extent
4752                  * for adjusting the disk offset below.  Only do this if the
4753                  * extent isn't compressed since our in ram offset may be past
4754                  * what we have actually allocated on disk.
4755                  */
4756                 if (!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4757                         offset_in_extent = em_start - em->start;
4758                 em_end = extent_map_end(em);
4759                 em_len = em_end - em_start;
4760                 flags = 0;
4761                 if (em->block_start < EXTENT_MAP_LAST_BYTE)
4762                         disko = em->block_start + offset_in_extent;
4763                 else
4764                         disko = 0;
4765 
4766                 /*
4767                  * bump off for our next call to get_extent
4768                  */
4769                 off = extent_map_end(em);
4770                 if (off >= max)
4771                         end = 1;
4772 
4773                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
4774                         end = 1;
4775                         flags |= FIEMAP_EXTENT_LAST;
4776                 } else if (em->block_start == EXTENT_MAP_INLINE) {
4777                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
4778                                   FIEMAP_EXTENT_NOT_ALIGNED);
4779                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
4780                         flags |= (FIEMAP_EXTENT_DELALLOC |
4781                                   FIEMAP_EXTENT_UNKNOWN);
4782                 } else if (fieinfo->fi_extents_max) {
4783                         u64 bytenr = em->block_start -
4784                                 (em->start - em->orig_start);
4785 
4786                         /*
4787                          * As btrfs supports shared space, this information
4788                          * can be exported to userspace tools via
4789                          * flag FIEMAP_EXTENT_SHARED.  If fi_extents_max == 0
4790                          * then we're just getting a count and we can skip the
4791                          * lookup stuff.
4792                          */
4793                         ret = btrfs_check_shared(root,
4794                                                  btrfs_ino(BTRFS_I(inode)),
4795                                                  bytenr, roots, tmp_ulist);
4796                         if (ret < 0)
4797                                 goto out_free;
4798                         if (ret)
4799                                 flags |= FIEMAP_EXTENT_SHARED;
4800                         ret = 0;
4801                 }
4802                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4803                         flags |= FIEMAP_EXTENT_ENCODED;
4804                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
4805                         flags |= FIEMAP_EXTENT_UNWRITTEN;
4806 
4807                 free_extent_map(em);
4808                 em = NULL;
4809                 if ((em_start >= last) || em_len == (u64)-1 ||
4810                    (last == (u64)-1 && isize <= em_end)) {
4811                         flags |= FIEMAP_EXTENT_LAST;
4812                         end = 1;
4813                 }
4814 
4815                 /* now scan forward to see if this is really the last extent. */
4816                 em = get_extent_skip_holes(inode, off, last_for_get_extent);
4817                 if (IS_ERR(em)) {
4818                         ret = PTR_ERR(em);
4819                         goto out;
4820                 }
4821                 if (!em) {
4822                         flags |= FIEMAP_EXTENT_LAST;
4823                         end = 1;
4824                 }
4825                 ret = emit_fiemap_extent(fieinfo, &cache, em_start, disko,
4826                                            em_len, flags);
4827                 if (ret) {
4828                         if (ret == 1)
4829                                 ret = 0;
4830                         goto out_free;
4831                 }
4832         }
4833 out_free:
4834         if (!ret)
4835                 ret = emit_last_fiemap_cache(fieinfo, &cache);
4836         free_extent_map(em);
4837 out:
4838         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4839                              &cached_state);
4840 
4841 out_free_ulist:
4842         btrfs_free_path(path);
4843         ulist_free(roots);
4844         ulist_free(tmp_ulist);
4845         return ret;
4846 }
4847 
4848 static void __free_extent_buffer(struct extent_buffer *eb)
4849 {
4850         btrfs_leak_debug_del(&eb->leak_list);
4851         kmem_cache_free(extent_buffer_cache, eb);
4852 }
4853 
4854 int extent_buffer_under_io(struct extent_buffer *eb)
4855 {
4856         return (atomic_read(&eb->io_pages) ||
4857                 test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
4858                 test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4859 }
4860 
4861 /*
4862  * Release all pages attached to the extent buffer.
4863  */
4864 static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb)
4865 {
4866         int i;
4867         int num_pages;
4868         int mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
4869 
4870         BUG_ON(extent_buffer_under_io(eb));
4871 
4872         num_pages = num_extent_pages(eb);
4873         for (i = 0; i < num_pages; i++) {
4874                 struct page *page = eb->pages[i];
4875 
4876                 if (!page)
4877                         continue;
4878                 if (mapped)
4879                         spin_lock(&page->mapping->private_lock);
4880                 /*
4881                  * We do this since we'll remove the pages after we've
4882                  * removed the eb from the radix tree, so we could race
4883                  * and have this page now attached to the new eb.  So
4884                  * only clear page_private if it's still connected to
4885                  * this eb.
4886                  */
4887                 if (PagePrivate(page) &&
4888                     page->private == (unsigned long)eb) {
4889                         BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4890                         BUG_ON(PageDirty(page));
4891                         BUG_ON(PageWriteback(page));
4892                         /*
4893                          * We need to make sure we haven't be attached
4894                          * to a new eb.
4895                          */
4896                         ClearPagePrivate(page);
4897                         set_page_private(page, 0);
4898                         /* One for the page private */
4899                         put_page(page);
4900                 }
4901 
4902                 if (mapped)
4903                         spin_unlock(&page->mapping->private_lock);
4904 
4905                 /* One for when we allocated the page */
4906                 put_page(page);
4907         }
4908 }
4909 
4910 /*
4911  * Helper for releasing the extent buffer.
4912  */
4913 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
4914 {
4915         btrfs_release_extent_buffer_pages(eb);
4916         __free_extent_buffer(eb);
4917 }
4918 
4919 static struct extent_buffer *
4920 __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
4921                       unsigned long len)
4922 {
4923         struct extent_buffer *eb = NULL;
4924 
4925         eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
4926         eb->start = start;
4927         eb->len = len;
4928         eb->fs_info = fs_info;
4929         eb->bflags = 0;
4930         rwlock_init(&eb->lock);
4931         atomic_set(&eb->blocking_readers, 0);
4932         eb->blocking_writers = 0;
4933         eb->lock_nested = false;
4934         init_waitqueue_head(&eb->write_lock_wq);
4935         init_waitqueue_head(&eb->read_lock_wq);
4936 
4937         btrfs_leak_debug_add(&eb->leak_list, &buffers);
4938 
4939         spin_lock_init(&eb->refs_lock);
4940         atomic_set(&eb->refs, 1);
4941         atomic_set(&eb->io_pages, 0);
4942 
4943         /*
4944          * Sanity checks, currently the maximum is 64k covered by 16x 4k pages
4945          */
4946         BUILD_BUG_ON(BTRFS_MAX_METADATA_BLOCKSIZE
4947                 > MAX_INLINE_EXTENT_BUFFER_SIZE);
4948         BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
4949 
4950 #ifdef CONFIG_BTRFS_DEBUG
4951         eb->spinning_writers = 0;
4952         atomic_set(&eb->spinning_readers, 0);
4953         atomic_set(&eb->read_locks, 0);
4954         eb->write_locks = 0;
4955 #endif
4956 
4957         return eb;
4958 }
4959 
4960 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
4961 {
4962         int i;
4963         struct page *p;
4964         struct extent_buffer *new;
4965         int num_pages = num_extent_pages(src);
4966 
4967         new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
4968         if (new == NULL)
4969                 return NULL;
4970 
4971         for (i = 0; i < num_pages; i++) {
4972                 p = alloc_page(GFP_NOFS);
4973                 if (!p) {
4974                         btrfs_release_extent_buffer(new);
4975                         return NULL;
4976                 }
4977                 attach_extent_buffer_page(new, p);
4978                 WARN_ON(PageDirty(p));
4979                 SetPageUptodate(p);
4980                 new->pages[i] = p;
4981                 copy_page(page_address(p), page_address(src->pages[i]));
4982         }
4983 
4984         set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
4985         set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);
4986 
4987         return new;
4988 }
4989 
4990 struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4991                                                   u64 start, unsigned long len)
4992 {
4993         struct extent_buffer *eb;
4994         int num_pages;
4995         int i;
4996 
4997         eb = __alloc_extent_buffer(fs_info, start, len);
4998         if (!eb)
4999                 return NULL;
5000 
5001         num_pages = num_extent_pages(eb);
5002         for (i = 0; i < num_pages; i++) {
5003                 eb->pages[i] = alloc_page(GFP_NOFS);
5004                 if (!eb->pages[i])
5005                         goto err;
5006         }
5007         set_extent_buffer_uptodate(eb);
5008         btrfs_set_header_nritems(eb, 0);
5009         set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
5010 
5011         return eb;
5012 err:
5013         for (; i > 0; i--)
5014                 __free_page(eb->pages[i - 1]);
5015         __free_extent_buffer(eb);
5016         return NULL;
5017 }
5018 
5019 struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
5020                                                 u64 start)
5021 {
5022         return __alloc_dummy_extent_buffer(fs_info, start, fs_info->nodesize);
5023 }
5024 
5025 static void check_buffer_tree_ref(struct extent_buffer *eb)
5026 {
5027         int refs;
5028         /* the ref bit is tricky.  We have to make sure it is set
5029          * if we have the buffer dirty.   Otherwise the
5030          * code to free a buffer can end up dropping a dirty
5031          * page
5032          *
5033          * Once the ref bit is set, it won't go away while the
5034          * buffer is dirty or in writeback, and it also won't
5035          * go away while we have the reference count on the
5036          * eb bumped.
5037          *
5038          * We can't just set the ref bit without bumping the
5039          * ref on the eb because free_extent_buffer might
5040          * see the ref bit and try to clear it.  If this happens
5041          * free_extent_buffer might end up dropping our original
5042          * ref by mistake and freeing the page before we are able
5043          * to add one more ref.
5044          *
5045          * So bump the ref count first, then set the bit.  If someone
5046          * beat us to it, drop the ref we added.
5047          */
5048         refs = atomic_read(&eb->refs);
5049         if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5050                 return;
5051 
5052         spin_lock(&eb->refs_lock);
5053         if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5054                 atomic_inc(&eb->refs);
5055         spin_unlock(&eb->refs_lock);
5056 }
5057 
5058 static void mark_extent_buffer_accessed(struct extent_buffer *eb,
5059                 struct page *accessed)
5060 {
5061         int num_pages, i;
5062 
5063         check_buffer_tree_ref(eb);
5064 
5065         num_pages = num_extent_pages(eb);
5066         for (i = 0; i < num_pages; i++) {
5067                 struct page *p = eb->pages[i];
5068 
5069                 if (p != accessed)
5070                         mark_page_accessed(p);
5071         }
5072 }
5073 
5074 struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
5075                                          u64 start)
5076 {
5077         struct extent_buffer *eb;
5078 
5079         rcu_read_lock();
5080         eb = radix_tree_lookup(&fs_info->buffer_radix,
5081                                start >> PAGE_SHIFT);
5082         if (eb && atomic_inc_not_zero(&eb->refs)) {
5083                 rcu_read_unlock();
5084                 /*
5085                  * Lock our eb's refs_lock to avoid races with
5086                  * free_extent_buffer. When we get our eb it might be flagged
5087                  * with EXTENT_BUFFER_STALE and another task running
5088                  * free_extent_buffer might have seen that flag set,
5089                  * eb->refs == 2, that the buffer isn't under IO (dirty and
5090                  * writeback flags not set) and it's still in the tree (flag
5091                  * EXTENT_BUFFER_TREE_REF set), therefore being in the process
5092                  * of decrementing the extent buffer's reference count twice.
5093                  * So here we could race and increment the eb's reference count,
5094                  * clear its stale flag, mark it as dirty and drop our reference
5095                  * before the other task finishes executing free_extent_buffer,
5096                  * which would later result in an attempt to free an extent
5097                  * buffer that is dirty.
5098                  */
5099                 if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
5100                         spin_lock(&eb->refs_lock);
5101                         spin_unlock(&eb->refs_lock);
5102                 }
5103                 mark_extent_buffer_accessed(eb, NULL);
5104                 return eb;
5105         }
5106         rcu_read_unlock();
5107 
5108         return NULL;
5109 }
5110 
5111 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
5112 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
5113                                         u64 start)
5114 {
5115         struct extent_buffer *eb, *exists = NULL;
5116         int ret;
5117 
5118         eb = find_extent_buffer(fs_info, start);
5119         if (eb)
5120                 return eb;
5121         eb = alloc_dummy_extent_buffer(fs_info, start);
5122         if (!eb)
5123                 return ERR_PTR(-ENOMEM);
5124         eb->fs_info = fs_info;
5125 again:
5126         ret = radix_tree_preload(GFP_NOFS);
5127         if (ret) {
5128                 exists = ERR_PTR(ret);
5129                 goto free_eb;
5130         }
5131         spin_lock(&fs_info->buffer_lock);
5132         ret = radix_tree_insert(&fs_info->buffer_radix,
5133                                 start >> PAGE_SHIFT, eb);
5134         spin_unlock(&fs_info->buffer_lock);
5135         radix_tree_preload_end();
5136         if (ret == -EEXIST) {
5137                 exists = find_extent_buffer(fs_info, start);
5138                 if (exists)
5139                         goto free_eb;
5140                 else
5141                         goto again;
5142         }
5143         check_buffer_tree_ref(eb);
5144         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
5145 
5146         return eb;
5147 free_eb:
5148         btrfs_release_extent_buffer(eb);
5149         return exists;
5150 }
5151 #endif
5152 
5153 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
5154                                           u64 start)
5155 {
5156         unsigned long len = fs_info->nodesize;
5157         int num_pages;
5158         int i;
5159         unsigned long index = start >> PAGE_SHIFT;
5160         struct extent_buffer *eb;
5161         struct extent_buffer *exists = NULL;
5162         struct page *p;
5163         struct address_space *mapping = fs_info->btree_inode->i_mapping;
5164         int uptodate = 1;
5165         int ret;
5166 
5167         if (!IS_ALIGNED(start, fs_info->sectorsize)) {
5168                 btrfs_err(fs_info, "bad tree block start %llu", start);
5169                 return ERR_PTR(-EINVAL);
5170         }
5171 
5172         eb = find_extent_buffer(fs_info, start);
5173         if (eb)
5174                 return eb;
5175 
5176         eb = __alloc_extent_buffer(fs_info, start, len);
5177         if (!eb)
5178                 return ERR_PTR(-ENOMEM);
5179 
5180         num_pages = num_extent_pages(eb);
5181         for (i = 0; i < num_pages; i++, index++) {
5182                 p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL);
5183                 if (!p) {
5184                         exists = ERR_PTR(-ENOMEM);
5185                         goto free_eb;
5186                 }
5187 
5188                 spin_lock(&mapping->private_lock);
5189                 if (PagePrivate(p)) {
5190                         /*
5191                          * We could have already allocated an eb for this page
5192                          * and attached one so lets see if we can get a ref on
5193                          * the existing eb, and if we can we know it's good and
5194                          * we can just return that one, else we know we can just
5195                          * overwrite page->private.
5196                          */
5197                         exists = (struct extent_buffer *)p->private;
5198                         if (atomic_inc_not_zero(&exists->refs)) {
5199                                 spin_unlock(&mapping->private_lock);
5200                                 unlock_page(p);
5201                                 put_page(p);
5202                                 mark_extent_buffer_accessed(exists, p);
5203                                 goto free_eb;
5204                         }
5205                         exists = NULL;
5206 
5207                         /*
5208                          * Do this so attach doesn't complain and we need to
5209                          * drop the ref the old guy had.
5210                          */
5211                         ClearPagePrivate(p);
5212                         WARN_ON(PageDirty(p));
5213                         put_page(p);
5214                 }
5215                 attach_extent_buffer_page(eb, p);
5216                 spin_unlock(&mapping->private_lock);
5217                 WARN_ON(PageDirty(p));
5218                 eb->pages[i] = p;
5219                 if (!PageUptodate(p))
5220                         uptodate = 0;
5221 
5222                 /*
5223                  * We can't unlock the pages just yet since the extent buffer
5224                  * hasn't been properly inserted in the radix tree, this
5225                  * opens a race with btree_releasepage which can free a page
5226                  * while we are still filling in all pages for the buffer and
5227                  * we could crash.
5228                  */
5229         }
5230         if (uptodate)
5231                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5232 again:
5233         ret = radix_tree_preload(GFP_NOFS);
5234         if (ret) {
5235                 exists = ERR_PTR(ret);
5236                 goto free_eb;
5237         }
5238 
5239         spin_lock(&fs_info->buffer_lock);
5240         ret = radix_tree_insert(&fs_info->buffer_radix,
5241                                 start >> PAGE_SHIFT, eb);
5242         spin_unlock(&fs_info->buffer_lock);
5243         radix_tree_preload_end();
5244         if (ret == -EEXIST) {
5245                 exists = find_extent_buffer(fs_info, start);
5246                 if (exists)
5247                         goto free_eb;
5248                 else
5249                         goto again;
5250         }
5251         /* add one reference for the tree */
5252         check_buffer_tree_ref(eb);
5253         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
5254 
5255         /*
5256          * Now it's safe to unlock the pages because any calls to
5257          * btree_releasepage will correctly detect that a page belongs to a
5258          * live buffer and won't free them prematurely.
5259          */
5260         for (i = 0; i < num_pages; i++)
5261                 unlock_page(eb->pages[i]);
5262         return eb;
5263 
5264 free_eb:
5265         WARN_ON(!atomic_dec_and_test(&eb->refs));
5266         for (i = 0; i < num_pages; i++) {
5267                 if (eb->pages[i])
5268                         unlock_page(eb->pages[i]);
5269         }
5270 
5271         btrfs_release_extent_buffer(eb);
5272         return exists;
5273 }
5274 
5275 static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
5276 {
5277         struct extent_buffer *eb =
5278                         container_of(head, struct extent_buffer, rcu_head);
5279 
5280         __free_extent_buffer(eb);
5281 }
5282 
5283 static int release_extent_buffer(struct extent_buffer *eb)
5284 {
5285         lockdep_assert_held(&eb->refs_lock);
5286 
5287         WARN_ON(atomic_read(&eb->refs) == 0);
5288         if (atomic_dec_and_test(&eb->refs)) {
5289                 if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) {
5290                         struct btrfs_fs_info *fs_info = eb->fs_info;
5291 
5292                         spin_unlock(&eb->refs_lock);
5293 
5294                         spin_lock(&fs_info->buffer_lock);
5295                         radix_tree_delete(&fs_info->buffer_radix,
5296                                           eb->start >> PAGE_SHIFT);
5297                         spin_unlock(&fs_info->buffer_lock);
5298                 } else {
5299                         spin_unlock(&eb->refs_lock);
5300                 }
5301 
5302                 /* Should be safe to release our pages at this point */
5303                 btrfs_release_extent_buffer_pages(eb);
5304 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
5305                 if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags))) {
5306                         __free_extent_buffer(eb);
5307                         return 1;
5308                 }
5309 #endif
5310                 call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
5311                 return 1;
5312         }
5313         spin_unlock(&eb->refs_lock);
5314 
5315         return 0;
5316 }
5317 
5318 void free_extent_buffer(struct extent_buffer *eb)
5319 {
5320         int refs;
5321         int old;
5322         if (!eb)
5323                 return;
5324 
5325         while (1) {
5326                 refs = atomic_read(&eb->refs);
5327                 if ((!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs <= 3)
5328                     || (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) &&
5329                         refs == 1))
5330                         break;
5331                 old = atomic_cmpxchg(&eb->refs, refs, refs - 1);
5332                 if (old == refs)
5333                         return;
5334         }
5335 
5336         spin_lock(&eb->refs_lock);
5337         if (atomic_read(&eb->refs) == 2 &&
5338             test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
5339             !extent_buffer_under_io(eb) &&
5340             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5341                 atomic_dec(&eb->refs);
5342 
5343         /*
5344          * I know this is terrible, but it's temporary until we stop tracking
5345          * the uptodate bits and such for the extent buffers.
5346          */
5347         release_extent_buffer(eb);
5348 }
5349 
5350 void free_extent_buffer_stale(struct extent_buffer *eb)
5351 {
5352         if (!eb)
5353                 return;
5354 
5355         spin_lock(&eb->refs_lock);
5356         set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
5357 
5358         if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
5359             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5360                 atomic_dec(&eb->refs);
5361         release_extent_buffer(eb);
5362 }
5363 
5364 void clear_extent_buffer_dirty(struct extent_buffer *eb)
5365 {
5366         int i;
5367         int num_pages;
5368         struct page *page;
5369 
5370         num_pages = num_extent_pages(eb);
5371 
5372         for (i = 0; i < num_pages; i++) {
5373                 page = eb->pages[i];
5374                 if (!PageDirty(page))
5375                         continue;
5376 
5377                 lock_page(page);
5378                 WARN_ON(!PagePrivate(page));
5379 
5380                 clear_page_dirty_for_io(page);
5381                 xa_lock_irq(&page->mapping->i_pages);
5382                 if (!PageDirty(page))
5383                         __xa_clear_mark(&page->mapping->i_pages,
5384                                         page_index(page), PAGECACHE_TAG_DIRTY);
5385                 xa_unlock_irq(&page->mapping->i_pages);
5386                 ClearPageError(page);
5387                 unlock_page(page);
5388         }
5389         WARN_ON(atomic_read(&eb->refs) == 0);
5390 }
5391 
5392 bool set_extent_buffer_dirty(struct extent_buffer *eb)
5393 {
5394         int i;
5395         int num_pages;
5396         bool was_dirty;
5397 
5398         check_buffer_tree_ref(eb);
5399 
5400         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
5401 
5402         num_pages = num_extent_pages(eb);
5403         WARN_ON(atomic_read(&eb->refs) == 0);
5404         WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
5405 
5406         if (!was_dirty)
5407                 for (i = 0; i < num_pages; i++)
5408                         set_page_dirty(eb->pages[i]);
5409 
5410 #ifdef CONFIG_BTRFS_DEBUG
5411         for (i = 0; i < num_pages; i++)
5412                 ASSERT(PageDirty(eb->pages[i]));
5413 #endif
5414 
5415         return was_dirty;
5416 }
5417 
5418 void clear_extent_buffer_uptodate(struct extent_buffer *eb)
5419 {
5420         int i;
5421         struct page *page;
5422         int num_pages;
5423 
5424         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5425         num_pages = num_extent_pages(eb);
5426         for (i = 0; i < num_pages; i++) {
5427                 page = eb->pages[i];
5428                 if (page)
5429                         ClearPageUptodate(page);
5430         }
5431 }
5432 
5433 void set_extent_buffer_uptodate(struct extent_buffer *eb)
5434 {
5435         int i;
5436         struct page *page;
5437         int num_pages;
5438 
5439         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5440         num_pages = num_extent_pages(eb);
5441         for (i = 0; i < num_pages; i++) {
5442                 page = eb->pages[i];
5443                 SetPageUptodate(page);
5444         }
5445 }
5446 
5447 int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num)
5448 {
5449         int i;
5450         struct page *page;
5451         int err;
5452         int ret = 0;
5453         int locked_pages = 0;
5454         int all_uptodate = 1;
5455         int num_pages;
5456         unsigned long num_reads = 0;
5457         struct bio *bio = NULL;
5458         unsigned long bio_flags = 0;
5459         struct extent_io_tree *tree = &BTRFS_I(eb->fs_info->btree_inode)->io_tree;
5460 
5461         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
5462                 return 0;
5463 
5464         num_pages = num_extent_pages(eb);
5465         for (i = 0; i < num_pages; i++) {
5466                 page = eb->pages[i];
5467                 if (wait == WAIT_NONE) {
5468                         if (!trylock_page(page))
5469                                 goto unlock_exit;
5470                 } else {
5471                         lock_page(page);
5472                 }
5473                 locked_pages++;
5474         }
5475         /*
5476          * We need to firstly lock all pages to make sure that
5477          * the uptodate bit of our pages won't be affected by
5478          * clear_extent_buffer_uptodate().
5479          */
5480         for (i = 0; i < num_pages; i++) {
5481                 page = eb->pages[i];
5482                 if (!PageUptodate(page)) {
5483                         num_reads++;
5484                         all_uptodate = 0;
5485                 }
5486         }
5487 
5488         if (all_uptodate) {
5489                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5490                 goto unlock_exit;
5491         }
5492 
5493         clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
5494         eb->read_mirror = 0;
5495         atomic_set(&eb->io_pages, num_reads);
5496         for (i = 0; i < num_pages; i++) {
5497                 page = eb->pages[i];
5498 
5499                 if (!PageUptodate(page)) {
5500                         if (ret) {
5501                                 atomic_dec(&eb->io_pages);
5502                                 unlock_page(page);
5503                                 continue;
5504                         }
5505 
5506                         ClearPageError(page);
5507                         err = __extent_read_full_page(tree, page,
5508                                                       btree_get_extent, &bio,
5509                                                       mirror_num, &bio_flags,
5510                                                       REQ_META);
5511                         if (err) {
5512                                 ret = err;
5513                                 /*
5514                                  * We use &bio in above __extent_read_full_page,
5515                                  * so we ensure that if it returns error, the
5516                                  * current page fails to add itself to bio and
5517                                  * it's been unlocked.
5518                                  *
5519                                  * We must dec io_pages by ourselves.
5520                                  */
5521                                 atomic_dec(&eb->io_pages);
5522                         }
5523                 } else {
5524                         unlock_page(page);
5525                 }
5526         }
5527 
5528         if (bio) {
5529                 err = submit_one_bio(bio, mirror_num, bio_flags);
5530                 if (err)
5531                         return err;
5532         }
5533 
5534         if (ret || wait != WAIT_COMPLETE)
5535                 return ret;
5536 
5537         for (i = 0; i < num_pages; i++) {
5538                 page = eb->pages[i];
5539                 wait_on_page_locked(page);
5540                 if (!PageUptodate(page))
5541                         ret = -EIO;
5542         }
5543 
5544         return ret;
5545 
5546 unlock_exit:
5547         while (locked_pages > 0) {
5548                 locked_pages--;
5549                 page = eb->pages[locked_pages];
5550                 unlock_page(page);
5551         }
5552         return ret;
5553 }
5554 
5555 void read_extent_buffer(const struct extent_buffer *eb, void *dstv,
5556                         unsigned long start, unsigned long len)
5557 {
5558         size_t cur;
5559         size_t offset;
5560         struct page *page;
5561         char *kaddr;
5562         char *dst = (char *)dstv;
5563         size_t start_offset = offset_in_page(eb->start);
5564         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5565 
5566         if (start + len > eb->len) {
5567                 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, wanted %lu %lu\n",
5568                      eb->start, eb->len, start, len);
5569                 memset(dst, 0, len);
5570                 return;
5571         }
5572 
5573         offset = offset_in_page(start_offset + start);
5574 
5575         while (len > 0) {
5576                 page = eb->pages[i];
5577 
5578                 cur = min(len, (PAGE_SIZE - offset));
5579                 kaddr = page_address(page);
5580                 memcpy(dst, kaddr + offset, cur);
5581 
5582                 dst += cur;
5583                 len -= cur;
5584                 offset = 0;
5585                 i++;
5586         }
5587 }
5588 
5589 int read_extent_buffer_to_user(const struct extent_buffer *eb,
5590                                void __user *dstv,
5591                                unsigned long start, unsigned long len)
5592 {
5593         size_t cur;
5594         size_t offset;
5595         struct page *page;
5596         char *kaddr;
5597         char __user *dst = (char __user *)dstv;
5598         size_t start_offset = offset_in_page(eb->start);
5599         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5600         int ret = 0;
5601 
5602         WARN_ON(start > eb->len);
5603         WARN_ON(start + len > eb->start + eb->len);
5604 
5605         offset = offset_in_page(start_offset + start);
5606 
5607         while (len > 0) {
5608                 page = eb->pages[i];
5609 
5610                 cur = min(len, (PAGE_SIZE - offset));
5611                 kaddr = page_address(page);
5612                 if (copy_to_user(dst, kaddr + offset, cur)) {
5613                         ret = -EFAULT;
5614                         break;
5615                 }
5616 
5617                 dst += cur;
5618                 len -= cur;
5619                 offset = 0;
5620                 i++;
5621         }
5622 
5623         return ret;
5624 }
5625 
5626 /*
5627  * return 0 if the item is found within a page.
5628  * return 1 if the item spans two pages.
5629  * return -EINVAL otherwise.
5630  */
5631 int map_private_extent_buffer(const struct extent_buffer *eb,
5632                               unsigned long start, unsigned long min_len,
5633                               char **map, unsigned long *map_start,
5634                               unsigned long *map_len)
5635 {
5636         size_t offset;
5637         char *kaddr;
5638         struct page *p;
5639         size_t start_offset = offset_in_page(eb->start);
5640         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5641         unsigned long end_i = (start_offset + start + min_len - 1) >>
5642                 PAGE_SHIFT;
5643 
5644         if (start + min_len > eb->len) {
5645                 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, wanted %lu %lu\n",
5646                        eb->start, eb->len, start, min_len);
5647                 return -EINVAL;
5648         }
5649 
5650         if (i != end_i)
5651                 return 1;
5652 
5653         if (i == 0) {
5654                 offset = start_offset;
5655                 *map_start = 0;
5656         } else {
5657                 offset = 0;
5658                 *map_start = ((u64)i << PAGE_SHIFT) - start_offset;
5659         }
5660 
5661         p = eb->pages[i];
5662         kaddr = page_address(p);
5663         *map = kaddr + offset;
5664         *map_len = PAGE_SIZE - offset;
5665         return 0;
5666 }
5667 
5668 int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
5669                          unsigned long start, unsigned long len)
5670 {
5671         size_t cur;
5672         size_t offset;
5673         struct page *page;
5674         char *kaddr;
5675         char *ptr = (char *)ptrv;
5676         size_t start_offset = offset_in_page(eb->start);
5677         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5678         int ret = 0;
5679 
5680         WARN_ON(start > eb->len);
5681         WARN_ON(start + len > eb->start + eb->len);
5682 
5683         offset = offset_in_page(start_offset + start);
5684 
5685         while (len > 0) {
5686                 page = eb->pages[i];
5687 
5688                 cur = min(len, (PAGE_SIZE - offset));
5689 
5690                 kaddr = page_address(page);
5691                 ret = memcmp(ptr, kaddr + offset, cur);
5692                 if (ret)
5693                         break;
5694 
5695                 ptr += cur;
5696                 len -= cur;
5697                 offset = 0;
5698                 i++;
5699         }
5700         return ret;
5701 }
5702 
5703 void write_extent_buffer_chunk_tree_uuid(struct extent_buffer *eb,
5704                 const void *srcv)
5705 {
5706         char *kaddr;
5707 
5708         WARN_ON(!PageUptodate(eb->pages[0]));
5709         kaddr = page_address(eb->pages[0]);
5710         memcpy(kaddr + offsetof(struct btrfs_header, chunk_tree_uuid), srcv,
5711                         BTRFS_FSID_SIZE);
5712 }
5713 
5714 void write_extent_buffer_fsid(struct extent_buffer *eb, const void *srcv)
5715 {
5716         char *kaddr;
5717 
5718         WARN_ON(!PageUptodate(eb->pages[0]));
5719         kaddr = page_address(eb->pages[0]);
5720         memcpy(kaddr + offsetof(struct btrfs_header, fsid), srcv,
5721                         BTRFS_FSID_SIZE);
5722 }
5723 
5724 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
5725                          unsigned long start, unsigned long len)
5726 {
5727         size_t cur;
5728         size_t offset;
5729         struct page *page;
5730         char *kaddr;
5731         char *src = (char *)srcv;
5732         size_t start_offset = offset_in_page(eb->start);
5733         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5734 
5735         WARN_ON(start > eb->len);
5736         WARN_ON(start + len > eb->start + eb->len);
5737 
5738         offset = offset_in_page(start_offset + start);
5739 
5740         while (len > 0) {
5741                 page = eb->pages[i];
5742                 WARN_ON(!PageUptodate(page));
5743 
5744                 cur = min(len, PAGE_SIZE - offset);
5745                 kaddr = page_address(page);
5746                 memcpy(kaddr + offset, src, cur);
5747 
5748                 src += cur;
5749                 len -= cur;
5750                 offset = 0;
5751                 i++;
5752         }
5753 }
5754 
5755 void memzero_extent_buffer(struct extent_buffer *eb, unsigned long start,
5756                 unsigned long len)
5757 {
5758         size_t cur;
5759         size_t offset;
5760         struct page *page;
5761         char *kaddr;
5762         size_t start_offset = offset_in_page(eb->start);
5763         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5764 
5765         WARN_ON(start > eb->len);
5766         WARN_ON(start + len > eb->start + eb->len);
5767 
5768         offset = offset_in_page(start_offset + start);
5769 
5770         while (len > 0) {
5771                 page = eb->pages[i];
5772                 WARN_ON(!PageUptodate(page));
5773 
5774                 cur = min(len, PAGE_SIZE - offset);
5775                 kaddr = page_address(page);
5776                 memset(kaddr + offset, 0, cur);
5777 
5778                 len -= cur;
5779                 offset = 0;
5780                 i++;
5781         }
5782 }
5783 
5784 void copy_extent_buffer_full(struct extent_buffer *dst,
5785                              struct extent_buffer *src)
5786 {
5787         int i;
5788         int num_pages;
5789 
5790         ASSERT(dst->len == src->len);
5791 
5792         num_pages = num_extent_pages(dst);
5793         for (i = 0; i < num_pages; i++)
5794                 copy_page(page_address(dst->pages[i]),
5795                                 page_address(src->pages[i]));
5796 }
5797 
5798 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
5799                         unsigned long dst_offset, unsigned long src_offset,
5800                         unsigned long len)
5801 {
5802         u64 dst_len = dst->len;
5803         size_t cur;
5804         size_t offset;
5805         struct page *page;
5806         char *kaddr;
5807         size_t start_offset = offset_in_page(dst->start);
5808         unsigned long i = (start_offset + dst_offset) >> PAGE_SHIFT;
5809 
5810         WARN_ON(src->len != dst_len);
5811 
5812         offset = offset_in_page(start_offset + dst_offset);
5813 
5814         while (len > 0) {
5815                 page = dst->pages[i];
5816                 WARN_ON(!PageUptodate(page));
5817 
5818                 cur = min(len, (unsigned long)(PAGE_SIZE - offset));
5819 
5820                 kaddr = page_address(page);
5821                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
5822 
5823                 src_offset += cur;
5824                 len -= cur;
5825                 offset = 0;
5826                 i++;
5827         }
5828 }
5829 
5830 /*
5831  * eb_bitmap_offset() - calculate the page and offset of the byte containing the
5832  * given bit number
5833  * @eb: the extent buffer
5834  * @start: offset of the bitmap item in the extent buffer
5835  * @nr: bit number
5836  * @page_index: return index of the page in the extent buffer that contains the
5837  * given bit number
5838  * @page_offset: return offset into the page given by page_index
5839  *
5840  * This helper hides the ugliness of finding the byte in an extent buffer which
5841  * contains a given bit.
5842  */
5843 static inline void eb_bitmap_offset(struct extent_buffer *eb,
5844                                     unsigned long start, unsigned long nr,
5845                                     unsigned long *page_index,
5846                                     size_t *page_offset)
5847 {
5848         size_t start_offset = offset_in_page(eb->start);
5849         size_t byte_offset = BIT_BYTE(nr);
5850         size_t offset;
5851 
5852         /*
5853          * The byte we want is the offset of the extent buffer + the offset of
5854          * the bitmap item in the extent buffer + the offset of the byte in the
5855          * bitmap item.
5856          */
5857         offset = start_offset + start + byte_offset;
5858 
5859         *page_index = offset >> PAGE_SHIFT;
5860         *page_offset = offset_in_page(offset);
5861 }
5862 
5863 /**
5864  * extent_buffer_test_bit - determine whether a bit in a bitmap item is set
5865  * @eb: the extent buffer
5866  * @start: offset of the bitmap item in the extent buffer
5867  * @nr: bit number to test
5868  */
5869 int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
5870                            unsigned long nr)
5871 {
5872         u8 *kaddr;
5873         struct page *page;
5874         unsigned long i;
5875         size_t offset;
5876 
5877         eb_bitmap_offset(eb, start, nr, &i, &offset);
5878         page = eb->pages[i];
5879         WARN_ON(!PageUptodate(page));
5880         kaddr = page_address(page);
5881         return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1)));
5882 }
5883 
5884 /**
5885  * extent_buffer_bitmap_set - set an area of a bitmap
5886  * @eb: the extent buffer
5887  * @start: offset of the bitmap item in the extent buffer
5888  * @pos: bit number of the first bit
5889  * @len: number of bits to set
5890  */
5891 void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
5892                               unsigned long pos, unsigned long len)
5893 {
5894         u8 *kaddr;
5895         struct page *page;
5896         unsigned long i;
5897         size_t offset;
5898         const unsigned int size = pos + len;
5899         int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5900         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(pos);
5901 
5902         eb_bitmap_offset(eb, start, pos, &i, &offset);
5903         page = eb->pages[i];
5904         WARN_ON(!PageUptodate(page));
5905         kaddr = page_address(page);
5906 
5907         while (len >= bits_to_set) {
5908                 kaddr[offset] |= mask_to_set;
5909                 len -= bits_to_set;
5910                 bits_to_set = BITS_PER_BYTE;
5911                 mask_to_set = ~0;
5912                 if (++offset >= PAGE_SIZE && len > 0) {
5913                         offset = 0;
5914                         page = eb->pages[++i];
5915                         WARN_ON(!PageUptodate(page));
5916                         kaddr = page_address(page);
5917                 }
5918         }
5919         if (len) {
5920                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
5921                 kaddr[offset] |= mask_to_set;
5922         }
5923 }
5924 
5925 
5926 /**
5927  * extent_buffer_bitmap_clear - clear an area of a bitmap
5928  * @eb: the extent buffer
5929  * @start: offset of the bitmap item in the extent buffer
5930  * @pos: bit number of the first bit
5931  * @len: number of bits to clear
5932  */
5933 void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
5934                                 unsigned long pos, unsigned long len)
5935 {
5936         u8 *kaddr;
5937         struct page *page;
5938         unsigned long i;
5939         size_t offset;
5940         const unsigned int size = pos + len;
5941         int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5942         u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos);
5943 
5944         eb_bitmap_offset(eb, start, pos, &i, &offset);
5945         page = eb->pages[i];
5946         WARN_ON(!PageUptodate(page));
5947         kaddr = page_address(page);
5948 
5949         while (len >= bits_to_clear) {
5950                 kaddr[offset] &= ~mask_to_clear;
5951                 len -= bits_to_clear;
5952                 bits_to_clear = BITS_PER_BYTE;
5953                 mask_to_clear = ~0;
5954                 if (++offset >= PAGE_SIZE && len > 0) {
5955                         offset = 0;
5956                         page = eb->pages[++i];
5957                         WARN_ON(!PageUptodate(page));
5958                         kaddr = page_address(page);
5959                 }
5960         }
5961         if (len) {
5962                 mask_to_clear &= BITMAP_LAST_BYTE_MASK(size);
5963                 kaddr[offset] &= ~mask_to_clear;
5964         }
5965 }
5966 
5967 static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
5968 {
5969         unsigned long distance = (src > dst) ? src - dst : dst - src;
5970         return distance < len;
5971 }
5972 
5973 static void copy_pages(struct page *dst_page, struct page *src_page,
5974                        unsigned long dst_off, unsigned long src_off,
5975                        unsigned long len)
5976 {
5977         char *dst_kaddr = page_address(dst_page);
5978         char *src_kaddr;
5979         int must_memmove = 0;
5980 
5981         if (dst_page != src_page) {
5982                 src_kaddr = page_address(src_page);
5983         } else {
5984                 src_kaddr = dst_kaddr;
5985                 if (areas_overlap(src_off, dst_off, len))
5986                         must_memmove = 1;
5987         }
5988 
5989         if (must_memmove)
5990                 memmove(dst_kaddr + dst_off, src_kaddr + src_off, len);
5991         else
5992                 memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
5993 }
5994 
5995 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5996                            unsigned long src_offset, unsigned long len)
5997 {
5998         struct btrfs_fs_info *fs_info = dst->fs_info;
5999         size_t cur;
6000         size_t dst_off_in_page;
6001         size_t src_off_in_page;
6002         size_t start_offset = offset_in_page(dst->start);
6003         unsigned long dst_i;
6004         unsigned long src_i;
6005 
6006         if (src_offset + len > dst->len) {
6007                 btrfs_err(fs_info,
6008                         "memmove bogus src_offset %lu move len %lu dst len %lu",
6009                          src_offset, len, dst->len);
6010                 BUG();
6011         }
6012         if (dst_offset + len > dst->len) {
6013                 btrfs_err(fs_info,
6014                         "memmove bogus dst_offset %lu move len %lu dst len %lu",
6015                          dst_offset, len, dst->len);
6016                 BUG();
6017         }
6018 
6019         while (len > 0) {
6020                 dst_off_in_page = offset_in_page(start_offset + dst_offset);
6021                 src_off_in_page = offset_in_page(start_offset + src_offset);
6022 
6023                 dst_i = (start_offset + dst_offset) >> PAGE_SHIFT;
6024                 src_i = (start_offset + src_offset) >> PAGE_SHIFT;
6025 
6026                 cur = min(len, (unsigned long)(PAGE_SIZE -
6027                                                src_off_in_page));
6028                 cur = min_t(unsigned long, cur,
6029                         (unsigned long)(PAGE_SIZE - dst_off_in_page));
6030 
6031                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
6032                            dst_off_in_page, src_off_in_page, cur);
6033 
6034                 src_offset += cur;
6035                 dst_offset += cur;
6036                 len -= cur;
6037         }
6038 }
6039 
6040 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
6041                            unsigned long src_offset, unsigned long len)
6042 {
6043         struct btrfs_fs_info *fs_info = dst->fs_info;
6044         size_t cur;
6045         size_t dst_off_in_page;
6046         size_t src_off_in_page;
6047         unsigned long dst_end = dst_offset + len - 1;
6048         unsigned long src_end = src_offset + len - 1;
6049         size_t start_offset = offset_in_page(dst->start);
6050         unsigned long dst_i;
6051         unsigned long src_i;
6052 
6053         if (src_offset + len > dst->len) {
6054                 btrfs_err(fs_info,
6055                           "memmove bogus src_offset %lu move len %lu len %lu",
6056                           src_offset, len, dst->len);
6057                 BUG();
6058         }
6059         if (dst_offset + len > dst->len) {
6060                 btrfs_err(fs_info,
6061                           "memmove bogus dst_offset %lu move len %lu len %lu",
6062                           dst_offset, len, dst->len);
6063                 BUG();
6064         }
6065         if (dst_offset < src_offset) {
6066                 memcpy_extent_buffer(dst, dst_offset, src_offset, len);
6067                 return;
6068         }
6069         while (len > 0) {
6070                 dst_i = (start_offset + dst_end) >> PAGE_SHIFT;
6071                 src_i = (start_offset + src_end) >> PAGE_SHIFT;
6072 
6073                 dst_off_in_page = offset_in_page(start_offset + dst_end);
6074                 src_off_in_page = offset_in_page(start_offset + src_end);
6075 
6076                 cur = min_t(unsigned long, len, src_off_in_page + 1);
6077                 cur = min(cur, dst_off_in_page + 1);
6078                 copy_pages(dst->pages[dst_i], dst->pages[src_i],
6079                            dst_off_in_page - cur + 1,
6080                            src_off_in_page - cur + 1, cur);
6081 
6082                 dst_end -= cur;
6083                 src_end -= cur;
6084                 len -= cur;
6085         }
6086 }
6087 
6088 int try_release_extent_buffer(struct page *page)
6089 {
6090         struct extent_buffer *eb;
6091 
6092         /*
6093          * We need to make sure nobody is attaching this page to an eb right
6094          * now.
6095          */
6096         spin_lock(&page->mapping->private_lock);
6097         if (!PagePrivate(page)) {
6098                 spin_unlock(&page->mapping->private_lock);
6099                 return 1;
6100         }
6101 
6102         eb = (struct extent_buffer *)page->private;
6103         BUG_ON(!eb);
6104 
6105         /*
6106          * This is a little awful but should be ok, we need to make sure that
6107          * the eb doesn't disappear out from under us while we're looking at
6108          * this page.
6109          */
6110         spin_lock(&eb->refs_lock);
6111         if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
6112                 spin_unlock(&eb->refs_lock);
6113                 spin_unlock(&page->mapping->private_lock);
6114                 return 0;
6115         }
6116         spin_unlock(&page->mapping->private_lock);
6117 
6118         /*
6119          * If tree ref isn't set then we know the ref on this eb is a real ref,
6120          * so just return, this page will likely be freed soon anyway.
6121          */
6122         if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
6123                 spin_unlock(&eb->refs_lock);
6124                 return 0;
6125         }
6126 
6127         return release_extent_buffer(eb);
6128 }
/* [<][>][^][v][top][bottom][index][help] */
root/fs/btrfs/extent_io.c

DEFINITIONS
