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TOMOYO Linux Cross Reference
Linux/fs/btrfs/extent_io.c

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  1 #include <linux/bitops.h>
  2 #include <linux/slab.h>
  3 #include <linux/bio.h>
  4 #include <linux/mm.h>
  5 #include <linux/pagemap.h>
  6 #include <linux/page-flags.h>
  7 #include <linux/spinlock.h>
  8 #include <linux/blkdev.h>
  9 #include <linux/swap.h>
 10 #include <linux/writeback.h>
 11 #include <linux/pagevec.h>
 12 #include <linux/prefetch.h>
 13 #include <linux/cleancache.h>
 14 #include "extent_io.h"
 15 #include "extent_map.h"
 16 #include "ctree.h"
 17 #include "btrfs_inode.h"
 18 #include "volumes.h"
 19 #include "check-integrity.h"
 20 #include "locking.h"
 21 #include "rcu-string.h"
 22 #include "backref.h"
 23 
 24 static struct kmem_cache *extent_state_cache;
 25 static struct kmem_cache *extent_buffer_cache;
 26 static struct bio_set *btrfs_bioset;
 27 
 28 static inline bool extent_state_in_tree(const struct extent_state *state)
 29 {
 30         return !RB_EMPTY_NODE(&state->rb_node);
 31 }
 32 
 33 #ifdef CONFIG_BTRFS_DEBUG
 34 static LIST_HEAD(buffers);
 35 static LIST_HEAD(states);
 36 
 37 static DEFINE_SPINLOCK(leak_lock);
 38 
 39 static inline
 40 void btrfs_leak_debug_add(struct list_head *new, struct list_head *head)
 41 {
 42         unsigned long flags;
 43 
 44         spin_lock_irqsave(&leak_lock, flags);
 45         list_add(new, head);
 46         spin_unlock_irqrestore(&leak_lock, flags);
 47 }
 48 
 49 static inline
 50 void btrfs_leak_debug_del(struct list_head *entry)
 51 {
 52         unsigned long flags;
 53 
 54         spin_lock_irqsave(&leak_lock, flags);
 55         list_del(entry);
 56         spin_unlock_irqrestore(&leak_lock, flags);
 57 }
 58 
 59 static inline
 60 void btrfs_leak_debug_check(void)
 61 {
 62         struct extent_state *state;
 63         struct extent_buffer *eb;
 64 
 65         while (!list_empty(&states)) {
 66                 state = list_entry(states.next, struct extent_state, leak_list);
 67                 pr_err("BTRFS: state leak: start %llu end %llu state %u in tree %d refs %d\n",
 68                        state->start, state->end, state->state,
 69                        extent_state_in_tree(state),
 70                        atomic_read(&state->refs));
 71                 list_del(&state->leak_list);
 72                 kmem_cache_free(extent_state_cache, state);
 73         }
 74 
 75         while (!list_empty(&buffers)) {
 76                 eb = list_entry(buffers.next, struct extent_buffer, leak_list);
 77                 printk(KERN_ERR "BTRFS: buffer leak start %llu len %lu "
 78                        "refs %d\n",
 79                        eb->start, eb->len, atomic_read(&eb->refs));
 80                 list_del(&eb->leak_list);
 81                 kmem_cache_free(extent_buffer_cache, eb);
 82         }
 83 }
 84 
 85 #define btrfs_debug_check_extent_io_range(tree, start, end)             \
 86         __btrfs_debug_check_extent_io_range(__func__, (tree), (start), (end))
 87 static inline void __btrfs_debug_check_extent_io_range(const char *caller,
 88                 struct extent_io_tree *tree, u64 start, u64 end)
 89 {
 90         struct inode *inode;
 91         u64 isize;
 92 
 93         if (!tree->mapping)
 94                 return;
 95 
 96         inode = tree->mapping->host;
 97         isize = i_size_read(inode);
 98         if (end >= PAGE_SIZE && (end % 2) == 0 && end != isize - 1) {
 99                 btrfs_debug_rl(BTRFS_I(inode)->root->fs_info,
100                     "%s: ino %llu isize %llu odd range [%llu,%llu]",
101                                 caller, btrfs_ino(inode), isize, start, end);
102         }
103 }
104 #else
105 #define btrfs_leak_debug_add(new, head) do {} while (0)
106 #define btrfs_leak_debug_del(entry)     do {} while (0)
107 #define btrfs_leak_debug_check()        do {} while (0)
108 #define btrfs_debug_check_extent_io_range(c, s, e)      do {} while (0)
109 #endif
110 
111 #define BUFFER_LRU_MAX 64
112 
113 struct tree_entry {
114         u64 start;
115         u64 end;
116         struct rb_node rb_node;
117 };
118 
119 struct extent_page_data {
120         struct bio *bio;
121         struct extent_io_tree *tree;
122         get_extent_t *get_extent;
123         unsigned long bio_flags;
124 
125         /* tells writepage not to lock the state bits for this range
126          * it still does the unlocking
127          */
128         unsigned int extent_locked:1;
129 
130         /* tells the submit_bio code to use a WRITE_SYNC */
131         unsigned int sync_io:1;
132 };
133 
134 static void add_extent_changeset(struct extent_state *state, unsigned bits,
135                                  struct extent_changeset *changeset,
136                                  int set)
137 {
138         int ret;
139 
140         if (!changeset)
141                 return;
142         if (set && (state->state & bits) == bits)
143                 return;
144         if (!set && (state->state & bits) == 0)
145                 return;
146         changeset->bytes_changed += state->end - state->start + 1;
147         ret = ulist_add(changeset->range_changed, state->start, state->end,
148                         GFP_ATOMIC);
149         /* ENOMEM */
150         BUG_ON(ret < 0);
151 }
152 
153 static noinline void flush_write_bio(void *data);
154 static inline struct btrfs_fs_info *
155 tree_fs_info(struct extent_io_tree *tree)
156 {
157         if (!tree->mapping)
158                 return NULL;
159         return btrfs_sb(tree->mapping->host->i_sb);
160 }
161 
162 int __init extent_io_init(void)
163 {
164         extent_state_cache = kmem_cache_create("btrfs_extent_state",
165                         sizeof(struct extent_state), 0,
166                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
167         if (!extent_state_cache)
168                 return -ENOMEM;
169 
170         extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
171                         sizeof(struct extent_buffer), 0,
172                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
173         if (!extent_buffer_cache)
174                 goto free_state_cache;
175 
176         btrfs_bioset = bioset_create(BIO_POOL_SIZE,
177                                      offsetof(struct btrfs_io_bio, bio));
178         if (!btrfs_bioset)
179                 goto free_buffer_cache;
180 
181         if (bioset_integrity_create(btrfs_bioset, BIO_POOL_SIZE))
182                 goto free_bioset;
183 
184         return 0;
185 
186 free_bioset:
187         bioset_free(btrfs_bioset);
188         btrfs_bioset = NULL;
189 
190 free_buffer_cache:
191         kmem_cache_destroy(extent_buffer_cache);
192         extent_buffer_cache = NULL;
193 
194 free_state_cache:
195         kmem_cache_destroy(extent_state_cache);
196         extent_state_cache = NULL;
197         return -ENOMEM;
198 }
199 
200 void extent_io_exit(void)
201 {
202         btrfs_leak_debug_check();
203 
204         /*
205          * Make sure all delayed rcu free are flushed before we
206          * destroy caches.
207          */
208         rcu_barrier();
209         kmem_cache_destroy(extent_state_cache);
210         kmem_cache_destroy(extent_buffer_cache);
211         if (btrfs_bioset)
212                 bioset_free(btrfs_bioset);
213 }
214 
215 void extent_io_tree_init(struct extent_io_tree *tree,
216                          struct address_space *mapping)
217 {
218         tree->state = RB_ROOT;
219         tree->ops = NULL;
220         tree->dirty_bytes = 0;
221         spin_lock_init(&tree->lock);
222         tree->mapping = mapping;
223 }
224 
225 static struct extent_state *alloc_extent_state(gfp_t mask)
226 {
227         struct extent_state *state;
228 
229         state = kmem_cache_alloc(extent_state_cache, mask);
230         if (!state)
231                 return state;
232         state->state = 0;
233         state->failrec = NULL;
234         RB_CLEAR_NODE(&state->rb_node);
235         btrfs_leak_debug_add(&state->leak_list, &states);
236         atomic_set(&state->refs, 1);
237         init_waitqueue_head(&state->wq);
238         trace_alloc_extent_state(state, mask, _RET_IP_);
239         return state;
240 }
241 
242 void free_extent_state(struct extent_state *state)
243 {
244         if (!state)
245                 return;
246         if (atomic_dec_and_test(&state->refs)) {
247                 WARN_ON(extent_state_in_tree(state));
248                 btrfs_leak_debug_del(&state->leak_list);
249                 trace_free_extent_state(state, _RET_IP_);
250                 kmem_cache_free(extent_state_cache, state);
251         }
252 }
253 
254 static struct rb_node *tree_insert(struct rb_root *root,
255                                    struct rb_node *search_start,
256                                    u64 offset,
257                                    struct rb_node *node,
258                                    struct rb_node ***p_in,
259                                    struct rb_node **parent_in)
260 {
261         struct rb_node **p;
262         struct rb_node *parent = NULL;
263         struct tree_entry *entry;
264 
265         if (p_in && parent_in) {
266                 p = *p_in;
267                 parent = *parent_in;
268                 goto do_insert;
269         }
270 
271         p = search_start ? &search_start : &root->rb_node;
272         while (*p) {
273                 parent = *p;
274                 entry = rb_entry(parent, struct tree_entry, rb_node);
275 
276                 if (offset < entry->start)
277                         p = &(*p)->rb_left;
278                 else if (offset > entry->end)
279                         p = &(*p)->rb_right;
280                 else
281                         return parent;
282         }
283 
284 do_insert:
285         rb_link_node(node, parent, p);
286         rb_insert_color(node, root);
287         return NULL;
288 }
289 
290 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
291                                       struct rb_node **prev_ret,
292                                       struct rb_node **next_ret,
293                                       struct rb_node ***p_ret,
294                                       struct rb_node **parent_ret)
295 {
296         struct rb_root *root = &tree->state;
297         struct rb_node **n = &root->rb_node;
298         struct rb_node *prev = NULL;
299         struct rb_node *orig_prev = NULL;
300         struct tree_entry *entry;
301         struct tree_entry *prev_entry = NULL;
302 
303         while (*n) {
304                 prev = *n;
305                 entry = rb_entry(prev, struct tree_entry, rb_node);
306                 prev_entry = entry;
307 
308                 if (offset < entry->start)
309                         n = &(*n)->rb_left;
310                 else if (offset > entry->end)
311                         n = &(*n)->rb_right;
312                 else
313                         return *n;
314         }
315 
316         if (p_ret)
317                 *p_ret = n;
318         if (parent_ret)
319                 *parent_ret = prev;
320 
321         if (prev_ret) {
322                 orig_prev = prev;
323                 while (prev && offset > prev_entry->end) {
324                         prev = rb_next(prev);
325                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
326                 }
327                 *prev_ret = prev;
328                 prev = orig_prev;
329         }
330 
331         if (next_ret) {
332                 prev_entry = rb_entry(prev, struct tree_entry, rb_node);
333                 while (prev && offset < prev_entry->start) {
334                         prev = rb_prev(prev);
335                         prev_entry = rb_entry(prev, struct tree_entry, rb_node);
336                 }
337                 *next_ret = prev;
338         }
339         return NULL;
340 }
341 
342 static inline struct rb_node *
343 tree_search_for_insert(struct extent_io_tree *tree,
344                        u64 offset,
345                        struct rb_node ***p_ret,
346                        struct rb_node **parent_ret)
347 {
348         struct rb_node *prev = NULL;
349         struct rb_node *ret;
350 
351         ret = __etree_search(tree, offset, &prev, NULL, p_ret, parent_ret);
352         if (!ret)
353                 return prev;
354         return ret;
355 }
356 
357 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
358                                           u64 offset)
359 {
360         return tree_search_for_insert(tree, offset, NULL, NULL);
361 }
362 
363 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
364                      struct extent_state *other)
365 {
366         if (tree->ops && tree->ops->merge_extent_hook)
367                 tree->ops->merge_extent_hook(tree->mapping->host, new,
368                                              other);
369 }
370 
371 /*
372  * utility function to look for merge candidates inside a given range.
373  * Any extents with matching state are merged together into a single
374  * extent in the tree.  Extents with EXTENT_IO in their state field
375  * are not merged because the end_io handlers need to be able to do
376  * operations on them without sleeping (or doing allocations/splits).
377  *
378  * This should be called with the tree lock held.
379  */
380 static void merge_state(struct extent_io_tree *tree,
381                         struct extent_state *state)
382 {
383         struct extent_state *other;
384         struct rb_node *other_node;
385 
386         if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
387                 return;
388 
389         other_node = rb_prev(&state->rb_node);
390         if (other_node) {
391                 other = rb_entry(other_node, struct extent_state, rb_node);
392                 if (other->end == state->start - 1 &&
393                     other->state == state->state) {
394                         merge_cb(tree, state, other);
395                         state->start = other->start;
396                         rb_erase(&other->rb_node, &tree->state);
397                         RB_CLEAR_NODE(&other->rb_node);
398                         free_extent_state(other);
399                 }
400         }
401         other_node = rb_next(&state->rb_node);
402         if (other_node) {
403                 other = rb_entry(other_node, struct extent_state, rb_node);
404                 if (other->start == state->end + 1 &&
405                     other->state == state->state) {
406                         merge_cb(tree, state, other);
407                         state->end = other->end;
408                         rb_erase(&other->rb_node, &tree->state);
409                         RB_CLEAR_NODE(&other->rb_node);
410                         free_extent_state(other);
411                 }
412         }
413 }
414 
415 static void set_state_cb(struct extent_io_tree *tree,
416                          struct extent_state *state, unsigned *bits)
417 {
418         if (tree->ops && tree->ops->set_bit_hook)
419                 tree->ops->set_bit_hook(tree->mapping->host, state, bits);
420 }
421 
422 static void clear_state_cb(struct extent_io_tree *tree,
423                            struct extent_state *state, unsigned *bits)
424 {
425         if (tree->ops && tree->ops->clear_bit_hook)
426                 tree->ops->clear_bit_hook(tree->mapping->host, state, bits);
427 }
428 
429 static void set_state_bits(struct extent_io_tree *tree,
430                            struct extent_state *state, unsigned *bits,
431                            struct extent_changeset *changeset);
432 
433 /*
434  * insert an extent_state struct into the tree.  'bits' are set on the
435  * struct before it is inserted.
436  *
437  * This may return -EEXIST if the extent is already there, in which case the
438  * state struct is freed.
439  *
440  * The tree lock is not taken internally.  This is a utility function and
441  * probably isn't what you want to call (see set/clear_extent_bit).
442  */
443 static int insert_state(struct extent_io_tree *tree,
444                         struct extent_state *state, u64 start, u64 end,
445                         struct rb_node ***p,
446                         struct rb_node **parent,
447                         unsigned *bits, struct extent_changeset *changeset)
448 {
449         struct rb_node *node;
450 
451         if (end < start)
452                 WARN(1, KERN_ERR "BTRFS: end < start %llu %llu\n",
453                        end, start);
454         state->start = start;
455         state->end = end;
456 
457         set_state_bits(tree, state, bits, changeset);
458 
459         node = tree_insert(&tree->state, NULL, end, &state->rb_node, p, parent);
460         if (node) {
461                 struct extent_state *found;
462                 found = rb_entry(node, struct extent_state, rb_node);
463                 printk(KERN_ERR "BTRFS: found node %llu %llu on insert of "
464                        "%llu %llu\n",
465                        found->start, found->end, start, end);
466                 return -EEXIST;
467         }
468         merge_state(tree, state);
469         return 0;
470 }
471 
472 static void split_cb(struct extent_io_tree *tree, struct extent_state *orig,
473                      u64 split)
474 {
475         if (tree->ops && tree->ops->split_extent_hook)
476                 tree->ops->split_extent_hook(tree->mapping->host, orig, split);
477 }
478 
479 /*
480  * split a given extent state struct in two, inserting the preallocated
481  * struct 'prealloc' as the newly created second half.  'split' indicates an
482  * offset inside 'orig' where it should be split.
483  *
484  * Before calling,
485  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
486  * are two extent state structs in the tree:
487  * prealloc: [orig->start, split - 1]
488  * orig: [ split, orig->end ]
489  *
490  * The tree locks are not taken by this function. They need to be held
491  * by the caller.
492  */
493 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
494                        struct extent_state *prealloc, u64 split)
495 {
496         struct rb_node *node;
497 
498         split_cb(tree, orig, split);
499 
500         prealloc->start = orig->start;
501         prealloc->end = split - 1;
502         prealloc->state = orig->state;
503         orig->start = split;
504 
505         node = tree_insert(&tree->state, &orig->rb_node, prealloc->end,
506                            &prealloc->rb_node, NULL, NULL);
507         if (node) {
508                 free_extent_state(prealloc);
509                 return -EEXIST;
510         }
511         return 0;
512 }
513 
514 static struct extent_state *next_state(struct extent_state *state)
515 {
516         struct rb_node *next = rb_next(&state->rb_node);
517         if (next)
518                 return rb_entry(next, struct extent_state, rb_node);
519         else
520                 return NULL;
521 }
522 
523 /*
524  * utility function to clear some bits in an extent state struct.
525  * it will optionally wake up any one waiting on this state (wake == 1).
526  *
527  * If no bits are set on the state struct after clearing things, the
528  * struct is freed and removed from the tree
529  */
530 static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
531                                             struct extent_state *state,
532                                             unsigned *bits, int wake,
533                                             struct extent_changeset *changeset)
534 {
535         struct extent_state *next;
536         unsigned bits_to_clear = *bits & ~EXTENT_CTLBITS;
537 
538         if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
539                 u64 range = state->end - state->start + 1;
540                 WARN_ON(range > tree->dirty_bytes);
541                 tree->dirty_bytes -= range;
542         }
543         clear_state_cb(tree, state, bits);
544         add_extent_changeset(state, bits_to_clear, changeset, 0);
545         state->state &= ~bits_to_clear;
546         if (wake)
547                 wake_up(&state->wq);
548         if (state->state == 0) {
549                 next = next_state(state);
550                 if (extent_state_in_tree(state)) {
551                         rb_erase(&state->rb_node, &tree->state);
552                         RB_CLEAR_NODE(&state->rb_node);
553                         free_extent_state(state);
554                 } else {
555                         WARN_ON(1);
556                 }
557         } else {
558                 merge_state(tree, state);
559                 next = next_state(state);
560         }
561         return next;
562 }
563 
564 static struct extent_state *
565 alloc_extent_state_atomic(struct extent_state *prealloc)
566 {
567         if (!prealloc)
568                 prealloc = alloc_extent_state(GFP_ATOMIC);
569 
570         return prealloc;
571 }
572 
573 static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
574 {
575         btrfs_panic(tree_fs_info(tree), err, "Locking error: "
576                     "Extent tree was modified by another "
577                     "thread while locked.");
578 }
579 
580 /*
581  * clear some bits on a range in the tree.  This may require splitting
582  * or inserting elements in the tree, so the gfp mask is used to
583  * indicate which allocations or sleeping are allowed.
584  *
585  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
586  * the given range from the tree regardless of state (ie for truncate).
587  *
588  * the range [start, end] is inclusive.
589  *
590  * This takes the tree lock, and returns 0 on success and < 0 on error.
591  */
592 static int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
593                               unsigned bits, int wake, int delete,
594                               struct extent_state **cached_state,
595                               gfp_t mask, struct extent_changeset *changeset)
596 {
597         struct extent_state *state;
598         struct extent_state *cached;
599         struct extent_state *prealloc = NULL;
600         struct rb_node *node;
601         u64 last_end;
602         int err;
603         int clear = 0;
604 
605         btrfs_debug_check_extent_io_range(tree, start, end);
606 
607         if (bits & EXTENT_DELALLOC)
608                 bits |= EXTENT_NORESERVE;
609 
610         if (delete)
611                 bits |= ~EXTENT_CTLBITS;
612         bits |= EXTENT_FIRST_DELALLOC;
613 
614         if (bits & (EXTENT_IOBITS | EXTENT_BOUNDARY))
615                 clear = 1;
616 again:
617         if (!prealloc && gfpflags_allow_blocking(mask)) {
618                 /*
619                  * Don't care for allocation failure here because we might end
620                  * up not needing the pre-allocated extent state at all, which
621                  * is the case if we only have in the tree extent states that
622                  * cover our input range and don't cover too any other range.
623                  * If we end up needing a new extent state we allocate it later.
624                  */
625                 prealloc = alloc_extent_state(mask);
626         }
627 
628         spin_lock(&tree->lock);
629         if (cached_state) {
630                 cached = *cached_state;
631 
632                 if (clear) {
633                         *cached_state = NULL;
634                         cached_state = NULL;
635                 }
636 
637                 if (cached && extent_state_in_tree(cached) &&
638                     cached->start <= start && cached->end > start) {
639                         if (clear)
640                                 atomic_dec(&cached->refs);
641                         state = cached;
642                         goto hit_next;
643                 }
644                 if (clear)
645                         free_extent_state(cached);
646         }
647         /*
648          * this search will find the extents that end after
649          * our range starts
650          */
651         node = tree_search(tree, start);
652         if (!node)
653                 goto out;
654         state = rb_entry(node, struct extent_state, rb_node);
655 hit_next:
656         if (state->start > end)
657                 goto out;
658         WARN_ON(state->end < start);
659         last_end = state->end;
660 
661         /* the state doesn't have the wanted bits, go ahead */
662         if (!(state->state & bits)) {
663                 state = next_state(state);
664                 goto next;
665         }
666 
667         /*
668          *     | ---- desired range ---- |
669          *  | state | or
670          *  | ------------- state -------------- |
671          *
672          * We need to split the extent we found, and may flip
673          * bits on second half.
674          *
675          * If the extent we found extends past our range, we
676          * just split and search again.  It'll get split again
677          * the next time though.
678          *
679          * If the extent we found is inside our range, we clear
680          * the desired bit on it.
681          */
682 
683         if (state->start < start) {
684                 prealloc = alloc_extent_state_atomic(prealloc);
685                 BUG_ON(!prealloc);
686                 err = split_state(tree, state, prealloc, start);
687                 if (err)
688                         extent_io_tree_panic(tree, err);
689 
690                 prealloc = NULL;
691                 if (err)
692                         goto out;
693                 if (state->end <= end) {
694                         state = clear_state_bit(tree, state, &bits, wake,
695                                                 changeset);
696                         goto next;
697                 }
698                 goto search_again;
699         }
700         /*
701          * | ---- desired range ---- |
702          *                        | state |
703          * We need to split the extent, and clear the bit
704          * on the first half
705          */
706         if (state->start <= end && state->end > end) {
707                 prealloc = alloc_extent_state_atomic(prealloc);
708                 BUG_ON(!prealloc);
709                 err = split_state(tree, state, prealloc, end + 1);
710                 if (err)
711                         extent_io_tree_panic(tree, err);
712 
713                 if (wake)
714                         wake_up(&state->wq);
715 
716                 clear_state_bit(tree, prealloc, &bits, wake, changeset);
717 
718                 prealloc = NULL;
719                 goto out;
720         }
721 
722         state = clear_state_bit(tree, state, &bits, wake, changeset);
723 next:
724         if (last_end == (u64)-1)
725                 goto out;
726         start = last_end + 1;
727         if (start <= end && state && !need_resched())
728                 goto hit_next;
729         goto search_again;
730 
731 out:
732         spin_unlock(&tree->lock);
733         if (prealloc)
734                 free_extent_state(prealloc);
735 
736         return 0;
737 
738 search_again:
739         if (start > end)
740                 goto out;
741         spin_unlock(&tree->lock);
742         if (gfpflags_allow_blocking(mask))
743                 cond_resched();
744         goto again;
745 }
746 
747 static void wait_on_state(struct extent_io_tree *tree,
748                           struct extent_state *state)
749                 __releases(tree->lock)
750                 __acquires(tree->lock)
751 {
752         DEFINE_WAIT(wait);
753         prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
754         spin_unlock(&tree->lock);
755         schedule();
756         spin_lock(&tree->lock);
757         finish_wait(&state->wq, &wait);
758 }
759 
760 /*
761  * waits for one or more bits to clear on a range in the state tree.
762  * The range [start, end] is inclusive.
763  * The tree lock is taken by this function
764  */
765 static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
766                             unsigned long bits)
767 {
768         struct extent_state *state;
769         struct rb_node *node;
770 
771         btrfs_debug_check_extent_io_range(tree, start, end);
772 
773         spin_lock(&tree->lock);
774 again:
775         while (1) {
776                 /*
777                  * this search will find all the extents that end after
778                  * our range starts
779                  */
780                 node = tree_search(tree, start);
781 process_node:
782                 if (!node)
783                         break;
784 
785                 state = rb_entry(node, struct extent_state, rb_node);
786 
787                 if (state->start > end)
788                         goto out;
789 
790                 if (state->state & bits) {
791                         start = state->start;
792                         atomic_inc(&state->refs);
793                         wait_on_state(tree, state);
794                         free_extent_state(state);
795                         goto again;
796                 }
797                 start = state->end + 1;
798 
799                 if (start > end)
800                         break;
801 
802                 if (!cond_resched_lock(&tree->lock)) {
803                         node = rb_next(node);
804                         goto process_node;
805                 }
806         }
807 out:
808         spin_unlock(&tree->lock);
809 }
810 
811 static void set_state_bits(struct extent_io_tree *tree,
812                            struct extent_state *state,
813                            unsigned *bits, struct extent_changeset *changeset)
814 {
815         unsigned bits_to_set = *bits & ~EXTENT_CTLBITS;
816 
817         set_state_cb(tree, state, bits);
818         if ((bits_to_set & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
819                 u64 range = state->end - state->start + 1;
820                 tree->dirty_bytes += range;
821         }
822         add_extent_changeset(state, bits_to_set, changeset, 1);
823         state->state |= bits_to_set;
824 }
825 
826 static void cache_state_if_flags(struct extent_state *state,
827                                  struct extent_state **cached_ptr,
828                                  unsigned flags)
829 {
830         if (cached_ptr && !(*cached_ptr)) {
831                 if (!flags || (state->state & flags)) {
832                         *cached_ptr = state;
833                         atomic_inc(&state->refs);
834                 }
835         }
836 }
837 
838 static void cache_state(struct extent_state *state,
839                         struct extent_state **cached_ptr)
840 {
841         return cache_state_if_flags(state, cached_ptr,
842                                     EXTENT_IOBITS | EXTENT_BOUNDARY);
843 }
844 
845 /*
846  * set some bits on a range in the tree.  This may require allocations or
847  * sleeping, so the gfp mask is used to indicate what is allowed.
848  *
849  * If any of the exclusive bits are set, this will fail with -EEXIST if some
850  * part of the range already has the desired bits set.  The start of the
851  * existing range is returned in failed_start in this case.
852  *
853  * [start, end] is inclusive This takes the tree lock.
854  */
855 
856 static int __must_check
857 __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
858                  unsigned bits, unsigned exclusive_bits,
859                  u64 *failed_start, struct extent_state **cached_state,
860                  gfp_t mask, struct extent_changeset *changeset)
861 {
862         struct extent_state *state;
863         struct extent_state *prealloc = NULL;
864         struct rb_node *node;
865         struct rb_node **p;
866         struct rb_node *parent;
867         int err = 0;
868         u64 last_start;
869         u64 last_end;
870 
871         btrfs_debug_check_extent_io_range(tree, start, end);
872 
873         bits |= EXTENT_FIRST_DELALLOC;
874 again:
875         if (!prealloc && gfpflags_allow_blocking(mask)) {
876                 prealloc = alloc_extent_state(mask);
877                 BUG_ON(!prealloc);
878         }
879 
880         spin_lock(&tree->lock);
881         if (cached_state && *cached_state) {
882                 state = *cached_state;
883                 if (state->start <= start && state->end > start &&
884                     extent_state_in_tree(state)) {
885                         node = &state->rb_node;
886                         goto hit_next;
887                 }
888         }
889         /*
890          * this search will find all the extents that end after
891          * our range starts.
892          */
893         node = tree_search_for_insert(tree, start, &p, &parent);
894         if (!node) {
895                 prealloc = alloc_extent_state_atomic(prealloc);
896                 BUG_ON(!prealloc);
897                 err = insert_state(tree, prealloc, start, end,
898                                    &p, &parent, &bits, changeset);
899                 if (err)
900                         extent_io_tree_panic(tree, err);
901 
902                 cache_state(prealloc, cached_state);
903                 prealloc = NULL;
904                 goto out;
905         }
906         state = rb_entry(node, struct extent_state, rb_node);
907 hit_next:
908         last_start = state->start;
909         last_end = state->end;
910 
911         /*
912          * | ---- desired range ---- |
913          * | state |
914          *
915          * Just lock what we found and keep going
916          */
917         if (state->start == start && state->end <= end) {
918                 if (state->state & exclusive_bits) {
919                         *failed_start = state->start;
920                         err = -EEXIST;
921                         goto out;
922                 }
923 
924                 set_state_bits(tree, state, &bits, changeset);
925                 cache_state(state, cached_state);
926                 merge_state(tree, state);
927                 if (last_end == (u64)-1)
928                         goto out;
929                 start = last_end + 1;
930                 state = next_state(state);
931                 if (start < end && state && state->start == start &&
932                     !need_resched())
933                         goto hit_next;
934                 goto search_again;
935         }
936 
937         /*
938          *     | ---- desired range ---- |
939          * | state |
940          *   or
941          * | ------------- state -------------- |
942          *
943          * We need to split the extent we found, and may flip bits on
944          * second half.
945          *
946          * If the extent we found extends past our
947          * range, we just split and search again.  It'll get split
948          * again the next time though.
949          *
950          * If the extent we found is inside our range, we set the
951          * desired bit on it.
952          */
953         if (state->start < start) {
954                 if (state->state & exclusive_bits) {
955                         *failed_start = start;
956                         err = -EEXIST;
957                         goto out;
958                 }
959 
960                 prealloc = alloc_extent_state_atomic(prealloc);
961                 BUG_ON(!prealloc);
962                 err = split_state(tree, state, prealloc, start);
963                 if (err)
964                         extent_io_tree_panic(tree, err);
965 
966                 prealloc = NULL;
967                 if (err)
968                         goto out;
969                 if (state->end <= end) {
970                         set_state_bits(tree, state, &bits, changeset);
971                         cache_state(state, cached_state);
972                         merge_state(tree, state);
973                         if (last_end == (u64)-1)
974                                 goto out;
975                         start = last_end + 1;
976                         state = next_state(state);
977                         if (start < end && state && state->start == start &&
978                             !need_resched())
979                                 goto hit_next;
980                 }
981                 goto search_again;
982         }
983         /*
984          * | ---- desired range ---- |
985          *     | state | or               | state |
986          *
987          * There's a hole, we need to insert something in it and
988          * ignore the extent we found.
989          */
990         if (state->start > start) {
991                 u64 this_end;
992                 if (end < last_start)
993                         this_end = end;
994                 else
995                         this_end = last_start - 1;
996 
997                 prealloc = alloc_extent_state_atomic(prealloc);
998                 BUG_ON(!prealloc);
999 
1000                 /*
1001                  * Avoid to free 'prealloc' if it can be merged with
1002                  * the later extent.
1003                  */
1004                 err = insert_state(tree, prealloc, start, this_end,
1005                                    NULL, NULL, &bits, changeset);
1006                 if (err)
1007                         extent_io_tree_panic(tree, err);
1008 
1009                 cache_state(prealloc, cached_state);
1010                 prealloc = NULL;
1011                 start = this_end + 1;
1012                 goto search_again;
1013         }
1014         /*
1015          * | ---- desired range ---- |
1016          *                        | state |
1017          * We need to split the extent, and set the bit
1018          * on the first half
1019          */
1020         if (state->start <= end && state->end > end) {
1021                 if (state->state & exclusive_bits) {
1022                         *failed_start = start;
1023                         err = -EEXIST;
1024                         goto out;
1025                 }
1026 
1027                 prealloc = alloc_extent_state_atomic(prealloc);
1028                 BUG_ON(!prealloc);
1029                 err = split_state(tree, state, prealloc, end + 1);
1030                 if (err)
1031                         extent_io_tree_panic(tree, err);
1032 
1033                 set_state_bits(tree, prealloc, &bits, changeset);
1034                 cache_state(prealloc, cached_state);
1035                 merge_state(tree, prealloc);
1036                 prealloc = NULL;
1037                 goto out;
1038         }
1039 
1040         goto search_again;
1041 
1042 out:
1043         spin_unlock(&tree->lock);
1044         if (prealloc)
1045                 free_extent_state(prealloc);
1046 
1047         return err;
1048 
1049 search_again:
1050         if (start > end)
1051                 goto out;
1052         spin_unlock(&tree->lock);
1053         if (gfpflags_allow_blocking(mask))
1054                 cond_resched();
1055         goto again;
1056 }
1057 
1058 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1059                    unsigned bits, u64 * failed_start,
1060                    struct extent_state **cached_state, gfp_t mask)
1061 {
1062         return __set_extent_bit(tree, start, end, bits, 0, failed_start,
1063                                 cached_state, mask, NULL);
1064 }
1065 
1066 
1067 /**
1068  * convert_extent_bit - convert all bits in a given range from one bit to
1069  *                      another
1070  * @tree:       the io tree to search
1071  * @start:      the start offset in bytes
1072  * @end:        the end offset in bytes (inclusive)
1073  * @bits:       the bits to set in this range
1074  * @clear_bits: the bits to clear in this range
1075  * @cached_state:       state that we're going to cache
1076  * @mask:       the allocation mask
1077  *
1078  * This will go through and set bits for the given range.  If any states exist
1079  * already in this range they are set with the given bit and cleared of the
1080  * clear_bits.  This is only meant to be used by things that are mergeable, ie
1081  * converting from say DELALLOC to DIRTY.  This is not meant to be used with
1082  * boundary bits like LOCK.
1083  */
1084 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1085                        unsigned bits, unsigned clear_bits,
1086                        struct extent_state **cached_state, gfp_t mask)
1087 {
1088         struct extent_state *state;
1089         struct extent_state *prealloc = NULL;
1090         struct rb_node *node;
1091         struct rb_node **p;
1092         struct rb_node *parent;
1093         int err = 0;
1094         u64 last_start;
1095         u64 last_end;
1096         bool first_iteration = true;
1097 
1098         btrfs_debug_check_extent_io_range(tree, start, end);
1099 
1100 again:
1101         if (!prealloc && gfpflags_allow_blocking(mask)) {
1102                 /*
1103                  * Best effort, don't worry if extent state allocation fails
1104                  * here for the first iteration. We might have a cached state
1105                  * that matches exactly the target range, in which case no
1106                  * extent state allocations are needed. We'll only know this
1107                  * after locking the tree.
1108                  */
1109                 prealloc = alloc_extent_state(mask);
1110                 if (!prealloc && !first_iteration)
1111                         return -ENOMEM;
1112         }
1113 
1114         spin_lock(&tree->lock);
1115         if (cached_state && *cached_state) {
1116                 state = *cached_state;
1117                 if (state->start <= start && state->end > start &&
1118                     extent_state_in_tree(state)) {
1119                         node = &state->rb_node;
1120                         goto hit_next;
1121                 }
1122         }
1123 
1124         /*
1125          * this search will find all the extents that end after
1126          * our range starts.
1127          */
1128         node = tree_search_for_insert(tree, start, &p, &parent);
1129         if (!node) {
1130                 prealloc = alloc_extent_state_atomic(prealloc);
1131                 if (!prealloc) {
1132                         err = -ENOMEM;
1133                         goto out;
1134                 }
1135                 err = insert_state(tree, prealloc, start, end,
1136                                    &p, &parent, &bits, NULL);
1137                 if (err)
1138                         extent_io_tree_panic(tree, err);
1139                 cache_state(prealloc, cached_state);
1140                 prealloc = NULL;
1141                 goto out;
1142         }
1143         state = rb_entry(node, struct extent_state, rb_node);
1144 hit_next:
1145         last_start = state->start;
1146         last_end = state->end;
1147 
1148         /*
1149          * | ---- desired range ---- |
1150          * | state |
1151          *
1152          * Just lock what we found and keep going
1153          */
1154         if (state->start == start && state->end <= end) {
1155                 set_state_bits(tree, state, &bits, NULL);
1156                 cache_state(state, cached_state);
1157                 state = clear_state_bit(tree, state, &clear_bits, 0, NULL);
1158                 if (last_end == (u64)-1)
1159                         goto out;
1160                 start = last_end + 1;
1161                 if (start < end && state && state->start == start &&
1162                     !need_resched())
1163                         goto hit_next;
1164                 goto search_again;
1165         }
1166 
1167         /*
1168          *     | ---- desired range ---- |
1169          * | state |
1170          *   or
1171          * | ------------- state -------------- |
1172          *
1173          * We need to split the extent we found, and may flip bits on
1174          * second half.
1175          *
1176          * If the extent we found extends past our
1177          * range, we just split and search again.  It'll get split
1178          * again the next time though.
1179          *
1180          * If the extent we found is inside our range, we set the
1181          * desired bit on it.
1182          */
1183         if (state->start < start) {
1184                 prealloc = alloc_extent_state_atomic(prealloc);
1185                 if (!prealloc) {
1186                         err = -ENOMEM;
1187                         goto out;
1188                 }
1189                 err = split_state(tree, state, prealloc, start);
1190                 if (err)
1191                         extent_io_tree_panic(tree, err);
1192                 prealloc = NULL;
1193                 if (err)
1194                         goto out;
1195                 if (state->end <= end) {
1196                         set_state_bits(tree, state, &bits, NULL);
1197                         cache_state(state, cached_state);
1198                         state = clear_state_bit(tree, state, &clear_bits, 0,
1199                                                 NULL);
1200                         if (last_end == (u64)-1)
1201                                 goto out;
1202                         start = last_end + 1;
1203                         if (start < end && state && state->start == start &&
1204                             !need_resched())
1205                                 goto hit_next;
1206                 }
1207                 goto search_again;
1208         }
1209         /*
1210          * | ---- desired range ---- |
1211          *     | state | or               | state |
1212          *
1213          * There's a hole, we need to insert something in it and
1214          * ignore the extent we found.
1215          */
1216         if (state->start > start) {
1217                 u64 this_end;
1218                 if (end < last_start)
1219                         this_end = end;
1220                 else
1221                         this_end = last_start - 1;
1222 
1223                 prealloc = alloc_extent_state_atomic(prealloc);
1224                 if (!prealloc) {
1225                         err = -ENOMEM;
1226                         goto out;
1227                 }
1228 
1229                 /*
1230                  * Avoid to free 'prealloc' if it can be merged with
1231                  * the later extent.
1232                  */
1233                 err = insert_state(tree, prealloc, start, this_end,
1234                                    NULL, NULL, &bits, NULL);
1235                 if (err)
1236                         extent_io_tree_panic(tree, err);
1237                 cache_state(prealloc, cached_state);
1238                 prealloc = NULL;
1239                 start = this_end + 1;
1240                 goto search_again;
1241         }
1242         /*
1243          * | ---- desired range ---- |
1244          *                        | state |
1245          * We need to split the extent, and set the bit
1246          * on the first half
1247          */
1248         if (state->start <= end && state->end > end) {
1249                 prealloc = alloc_extent_state_atomic(prealloc);
1250                 if (!prealloc) {
1251                         err = -ENOMEM;
1252                         goto out;
1253                 }
1254 
1255                 err = split_state(tree, state, prealloc, end + 1);
1256                 if (err)
1257                         extent_io_tree_panic(tree, err);
1258 
1259                 set_state_bits(tree, prealloc, &bits, NULL);
1260                 cache_state(prealloc, cached_state);
1261                 clear_state_bit(tree, prealloc, &clear_bits, 0, NULL);
1262                 prealloc = NULL;
1263                 goto out;
1264         }
1265 
1266         goto search_again;
1267 
1268 out:
1269         spin_unlock(&tree->lock);
1270         if (prealloc)
1271                 free_extent_state(prealloc);
1272 
1273         return err;
1274 
1275 search_again:
1276         if (start > end)
1277                 goto out;
1278         spin_unlock(&tree->lock);
1279         if (gfpflags_allow_blocking(mask))
1280                 cond_resched();
1281         first_iteration = false;
1282         goto again;
1283 }
1284 
1285 /* wrappers around set/clear extent bit */
1286 int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1287                            unsigned bits, gfp_t mask,
1288                            struct extent_changeset *changeset)
1289 {
1290         /*
1291          * We don't support EXTENT_LOCKED yet, as current changeset will
1292          * record any bits changed, so for EXTENT_LOCKED case, it will
1293          * either fail with -EEXIST or changeset will record the whole
1294          * range.
1295          */
1296         BUG_ON(bits & EXTENT_LOCKED);
1297 
1298         return __set_extent_bit(tree, start, end, bits, 0, NULL, NULL, mask,
1299                                 changeset);
1300 }
1301 
1302 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1303                      unsigned bits, int wake, int delete,
1304                      struct extent_state **cached, gfp_t mask)
1305 {
1306         return __clear_extent_bit(tree, start, end, bits, wake, delete,
1307                                   cached, mask, NULL);
1308 }
1309 
1310 int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1311                              unsigned bits, gfp_t mask,
1312                              struct extent_changeset *changeset)
1313 {
1314         /*
1315          * Don't support EXTENT_LOCKED case, same reason as
1316          * set_record_extent_bits().
1317          */
1318         BUG_ON(bits & EXTENT_LOCKED);
1319 
1320         return __clear_extent_bit(tree, start, end, bits, 0, 0, NULL, mask,
1321                                   changeset);
1322 }
1323 
1324 /*
1325  * either insert or lock state struct between start and end use mask to tell
1326  * us if waiting is desired.
1327  */
1328 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1329                      struct extent_state **cached_state)
1330 {
1331         int err;
1332         u64 failed_start;
1333 
1334         while (1) {
1335                 err = __set_extent_bit(tree, start, end, EXTENT_LOCKED,
1336                                        EXTENT_LOCKED, &failed_start,
1337                                        cached_state, GFP_NOFS, NULL);
1338                 if (err == -EEXIST) {
1339                         wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1340                         start = failed_start;
1341                 } else
1342                         break;
1343                 WARN_ON(start > end);
1344         }
1345         return err;
1346 }
1347 
1348 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1349 {
1350         int err;
1351         u64 failed_start;
1352 
1353         err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1354                                &failed_start, NULL, GFP_NOFS, NULL);
1355         if (err == -EEXIST) {
1356                 if (failed_start > start)
1357                         clear_extent_bit(tree, start, failed_start - 1,
1358                                          EXTENT_LOCKED, 1, 0, NULL, GFP_NOFS);
1359                 return 0;
1360         }
1361         return 1;
1362 }
1363 
1364 void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
1365 {
1366         unsigned long index = start >> PAGE_SHIFT;
1367         unsigned long end_index = end >> PAGE_SHIFT;
1368         struct page *page;
1369 
1370         while (index <= end_index) {
1371                 page = find_get_page(inode->i_mapping, index);
1372                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1373                 clear_page_dirty_for_io(page);
1374                 put_page(page);
1375                 index++;
1376         }
1377 }
1378 
1379 void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
1380 {
1381         unsigned long index = start >> PAGE_SHIFT;
1382         unsigned long end_index = end >> PAGE_SHIFT;
1383         struct page *page;
1384 
1385         while (index <= end_index) {
1386                 page = find_get_page(inode->i_mapping, index);
1387                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1388                 __set_page_dirty_nobuffers(page);
1389                 account_page_redirty(page);
1390                 put_page(page);
1391                 index++;
1392         }
1393 }
1394 
1395 /*
1396  * helper function to set both pages and extents in the tree writeback
1397  */
1398 static void set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1399 {
1400         unsigned long index = start >> PAGE_SHIFT;
1401         unsigned long end_index = end >> PAGE_SHIFT;
1402         struct page *page;
1403 
1404         while (index <= end_index) {
1405                 page = find_get_page(tree->mapping, index);
1406                 BUG_ON(!page); /* Pages should be in the extent_io_tree */
1407                 set_page_writeback(page);
1408                 put_page(page);
1409                 index++;
1410         }
1411 }
1412 
1413 /* find the first state struct with 'bits' set after 'start', and
1414  * return it.  tree->lock must be held.  NULL will returned if
1415  * nothing was found after 'start'
1416  */
1417 static struct extent_state *
1418 find_first_extent_bit_state(struct extent_io_tree *tree,
1419                             u64 start, unsigned bits)
1420 {
1421         struct rb_node *node;
1422         struct extent_state *state;
1423 
1424         /*
1425          * this search will find all the extents that end after
1426          * our range starts.
1427          */
1428         node = tree_search(tree, start);
1429         if (!node)
1430                 goto out;
1431 
1432         while (1) {
1433                 state = rb_entry(node, struct extent_state, rb_node);
1434                 if (state->end >= start && (state->state & bits))
1435                         return state;
1436 
1437                 node = rb_next(node);
1438                 if (!node)
1439                         break;
1440         }
1441 out:
1442         return NULL;
1443 }
1444 
1445 /*
1446  * find the first offset in the io tree with 'bits' set. zero is
1447  * returned if we find something, and *start_ret and *end_ret are
1448  * set to reflect the state struct that was found.
1449  *
1450  * If nothing was found, 1 is returned. If found something, return 0.
1451  */
1452 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1453                           u64 *start_ret, u64 *end_ret, unsigned bits,
1454                           struct extent_state **cached_state)
1455 {
1456         struct extent_state *state;
1457         struct rb_node *n;
1458         int ret = 1;
1459 
1460         spin_lock(&tree->lock);
1461         if (cached_state && *cached_state) {
1462                 state = *cached_state;
1463                 if (state->end == start - 1 && extent_state_in_tree(state)) {
1464                         n = rb_next(&state->rb_node);
1465                         while (n) {
1466                                 state = rb_entry(n, struct extent_state,
1467                                                  rb_node);
1468                                 if (state->state & bits)
1469                                         goto got_it;
1470                                 n = rb_next(n);
1471                         }
1472                         free_extent_state(*cached_state);
1473                         *cached_state = NULL;
1474                         goto out;
1475                 }
1476                 free_extent_state(*cached_state);
1477                 *cached_state = NULL;
1478         }
1479 
1480         state = find_first_extent_bit_state(tree, start, bits);
1481 got_it:
1482         if (state) {
1483                 cache_state_if_flags(state, cached_state, 0);
1484                 *start_ret = state->start;
1485                 *end_ret = state->end;
1486                 ret = 0;
1487         }
1488 out:
1489         spin_unlock(&tree->lock);
1490         return ret;
1491 }
1492 
1493 /*
1494  * find a contiguous range of bytes in the file marked as delalloc, not
1495  * more than 'max_bytes'.  start and end are used to return the range,
1496  *
1497  * 1 is returned if we find something, 0 if nothing was in the tree
1498  */
1499 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1500                                         u64 *start, u64 *end, u64 max_bytes,
1501                                         struct extent_state **cached_state)
1502 {
1503         struct rb_node *node;
1504         struct extent_state *state;
1505         u64 cur_start = *start;
1506         u64 found = 0;
1507         u64 total_bytes = 0;
1508 
1509         spin_lock(&tree->lock);
1510 
1511         /*
1512          * this search will find all the extents that end after
1513          * our range starts.
1514          */
1515         node = tree_search(tree, cur_start);
1516         if (!node) {
1517                 if (!found)
1518                         *end = (u64)-1;
1519                 goto out;
1520         }
1521 
1522         while (1) {
1523                 state = rb_entry(node, struct extent_state, rb_node);
1524                 if (found && (state->start != cur_start ||
1525                               (state->state & EXTENT_BOUNDARY))) {
1526                         goto out;
1527                 }
1528                 if (!(state->state & EXTENT_DELALLOC)) {
1529                         if (!found)
1530                                 *end = state->end;
1531                         goto out;
1532                 }
1533                 if (!found) {
1534                         *start = state->start;
1535                         *cached_state = state;
1536                         atomic_inc(&state->refs);
1537                 }
1538                 found++;
1539                 *end = state->end;
1540                 cur_start = state->end + 1;
1541                 node = rb_next(node);
1542                 total_bytes += state->end - state->start + 1;
1543                 if (total_bytes >= max_bytes)
1544                         break;
1545                 if (!node)
1546                         break;
1547         }
1548 out:
1549         spin_unlock(&tree->lock);
1550         return found;
1551 }
1552 
1553 static noinline void __unlock_for_delalloc(struct inode *inode,
1554                                            struct page *locked_page,
1555                                            u64 start, u64 end)
1556 {
1557         int ret;
1558         struct page *pages[16];
1559         unsigned long index = start >> PAGE_SHIFT;
1560         unsigned long end_index = end >> PAGE_SHIFT;
1561         unsigned long nr_pages = end_index - index + 1;
1562         int i;
1563 
1564         if (index == locked_page->index && end_index == index)
1565                 return;
1566 
1567         while (nr_pages > 0) {
1568                 ret = find_get_pages_contig(inode->i_mapping, index,
1569                                      min_t(unsigned long, nr_pages,
1570                                      ARRAY_SIZE(pages)), pages);
1571                 for (i = 0; i < ret; i++) {
1572                         if (pages[i] != locked_page)
1573                                 unlock_page(pages[i]);
1574                         put_page(pages[i]);
1575                 }
1576                 nr_pages -= ret;
1577                 index += ret;
1578                 cond_resched();
1579         }
1580 }
1581 
1582 static noinline int lock_delalloc_pages(struct inode *inode,
1583                                         struct page *locked_page,
1584                                         u64 delalloc_start,
1585                                         u64 delalloc_end)
1586 {
1587         unsigned long index = delalloc_start >> PAGE_SHIFT;
1588         unsigned long start_index = index;
1589         unsigned long end_index = delalloc_end >> PAGE_SHIFT;
1590         unsigned long pages_locked = 0;
1591         struct page *pages[16];
1592         unsigned long nrpages;
1593         int ret;
1594         int i;
1595 
1596         /* the caller is responsible for locking the start index */
1597         if (index == locked_page->index && index == end_index)
1598                 return 0;
1599 
1600         /* skip the page at the start index */
1601         nrpages = end_index - index + 1;
1602         while (nrpages > 0) {
1603                 ret = find_get_pages_contig(inode->i_mapping, index,
1604                                      min_t(unsigned long,
1605                                      nrpages, ARRAY_SIZE(pages)), pages);
1606                 if (ret == 0) {
1607                         ret = -EAGAIN;
1608                         goto done;
1609                 }
1610                 /* now we have an array of pages, lock them all */
1611                 for (i = 0; i < ret; i++) {
1612                         /*
1613                          * the caller is taking responsibility for
1614                          * locked_page
1615                          */
1616                         if (pages[i] != locked_page) {
1617                                 lock_page(pages[i]);
1618                                 if (!PageDirty(pages[i]) ||
1619                                     pages[i]->mapping != inode->i_mapping) {
1620                                         ret = -EAGAIN;
1621                                         unlock_page(pages[i]);
1622                                         put_page(pages[i]);
1623                                         goto done;
1624                                 }
1625                         }
1626                         put_page(pages[i]);
1627                         pages_locked++;
1628                 }
1629                 nrpages -= ret;
1630                 index += ret;
1631                 cond_resched();
1632         }
1633         ret = 0;
1634 done:
1635         if (ret && pages_locked) {
1636                 __unlock_for_delalloc(inode, locked_page,
1637                               delalloc_start,
1638                               ((u64)(start_index + pages_locked - 1)) <<
1639                               PAGE_SHIFT);
1640         }
1641         return ret;
1642 }
1643 
1644 /*
1645  * find a contiguous range of bytes in the file marked as delalloc, not
1646  * more than 'max_bytes'.  start and end are used to return the range,
1647  *
1648  * 1 is returned if we find something, 0 if nothing was in the tree
1649  */
1650 STATIC u64 find_lock_delalloc_range(struct inode *inode,
1651                                     struct extent_io_tree *tree,
1652                                     struct page *locked_page, u64 *start,
1653                                     u64 *end, u64 max_bytes)
1654 {
1655         u64 delalloc_start;
1656         u64 delalloc_end;
1657         u64 found;
1658         struct extent_state *cached_state = NULL;
1659         int ret;
1660         int loops = 0;
1661 
1662 again:
1663         /* step one, find a bunch of delalloc bytes starting at start */
1664         delalloc_start = *start;
1665         delalloc_end = 0;
1666         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1667                                     max_bytes, &cached_state);
1668         if (!found || delalloc_end <= *start) {
1669                 *start = delalloc_start;
1670                 *end = delalloc_end;
1671                 free_extent_state(cached_state);
1672                 return 0;
1673         }
1674 
1675         /*
1676          * start comes from the offset of locked_page.  We have to lock
1677          * pages in order, so we can't process delalloc bytes before
1678          * locked_page
1679          */
1680         if (delalloc_start < *start)
1681                 delalloc_start = *start;
1682 
1683         /*
1684          * make sure to limit the number of pages we try to lock down
1685          */
1686         if (delalloc_end + 1 - delalloc_start > max_bytes)
1687                 delalloc_end = delalloc_start + max_bytes - 1;
1688 
1689         /* step two, lock all the pages after the page that has start */
1690         ret = lock_delalloc_pages(inode, locked_page,
1691                                   delalloc_start, delalloc_end);
1692         if (ret == -EAGAIN) {
1693                 /* some of the pages are gone, lets avoid looping by
1694                  * shortening the size of the delalloc range we're searching
1695                  */
1696                 free_extent_state(cached_state);
1697                 cached_state = NULL;
1698                 if (!loops) {
1699                         max_bytes = PAGE_SIZE;
1700                         loops = 1;
1701                         goto again;
1702                 } else {
1703                         found = 0;
1704                         goto out_failed;
1705                 }
1706         }
1707         BUG_ON(ret); /* Only valid values are 0 and -EAGAIN */
1708 
1709         /* step three, lock the state bits for the whole range */
1710         lock_extent_bits(tree, delalloc_start, delalloc_end, &cached_state);
1711 
1712         /* then test to make sure it is all still delalloc */
1713         ret = test_range_bit(tree, delalloc_start, delalloc_end,
1714                              EXTENT_DELALLOC, 1, cached_state);
1715         if (!ret) {
1716                 unlock_extent_cached(tree, delalloc_start, delalloc_end,
1717                                      &cached_state, GFP_NOFS);
1718                 __unlock_for_delalloc(inode, locked_page,
1719                               delalloc_start, delalloc_end);
1720                 cond_resched();
1721                 goto again;
1722         }
1723         free_extent_state(cached_state);
1724         *start = delalloc_start;
1725         *end = delalloc_end;
1726 out_failed:
1727         return found;
1728 }
1729 
1730 void extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
1731                                  struct page *locked_page,
1732                                  unsigned clear_bits,
1733                                  unsigned long page_ops)
1734 {
1735         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
1736         int ret;
1737         struct page *pages[16];
1738         unsigned long index = start >> PAGE_SHIFT;
1739         unsigned long end_index = end >> PAGE_SHIFT;
1740         unsigned long nr_pages = end_index - index + 1;
1741         int i;
1742 
1743         clear_extent_bit(tree, start, end, clear_bits, 1, 0, NULL, GFP_NOFS);
1744         if (page_ops == 0)
1745                 return;
1746 
1747         if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
1748                 mapping_set_error(inode->i_mapping, -EIO);
1749 
1750         while (nr_pages > 0) {
1751                 ret = find_get_pages_contig(inode->i_mapping, index,
1752                                      min_t(unsigned long,
1753                                      nr_pages, ARRAY_SIZE(pages)), pages);
1754                 for (i = 0; i < ret; i++) {
1755 
1756                         if (page_ops & PAGE_SET_PRIVATE2)
1757                                 SetPagePrivate2(pages[i]);
1758 
1759                         if (pages[i] == locked_page) {
1760                                 put_page(pages[i]);
1761                                 continue;
1762                         }
1763                         if (page_ops & PAGE_CLEAR_DIRTY)
1764                                 clear_page_dirty_for_io(pages[i]);
1765                         if (page_ops & PAGE_SET_WRITEBACK)
1766                                 set_page_writeback(pages[i]);
1767                         if (page_ops & PAGE_SET_ERROR)
1768                                 SetPageError(pages[i]);
1769                         if (page_ops & PAGE_END_WRITEBACK)
1770                                 end_page_writeback(pages[i]);
1771                         if (page_ops & PAGE_UNLOCK)
1772                                 unlock_page(pages[i]);
1773                         put_page(pages[i]);
1774                 }
1775                 nr_pages -= ret;
1776                 index += ret;
1777                 cond_resched();
1778         }
1779 }
1780 
1781 /*
1782  * count the number of bytes in the tree that have a given bit(s)
1783  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1784  * cached.  The total number found is returned.
1785  */
1786 u64 count_range_bits(struct extent_io_tree *tree,
1787                      u64 *start, u64 search_end, u64 max_bytes,
1788                      unsigned bits, int contig)
1789 {
1790         struct rb_node *node;
1791         struct extent_state *state;
1792         u64 cur_start = *start;
1793         u64 total_bytes = 0;
1794         u64 last = 0;
1795         int found = 0;
1796 
1797         if (WARN_ON(search_end <= cur_start))
1798                 return 0;
1799 
1800         spin_lock(&tree->lock);
1801         if (cur_start == 0 && bits == EXTENT_DIRTY) {
1802                 total_bytes = tree->dirty_bytes;
1803                 goto out;
1804         }
1805         /*
1806          * this search will find all the extents that end after
1807          * our range starts.
1808          */
1809         node = tree_search(tree, cur_start);
1810         if (!node)
1811                 goto out;
1812 
1813         while (1) {
1814                 state = rb_entry(node, struct extent_state, rb_node);
1815                 if (state->start > search_end)
1816                         break;
1817                 if (contig && found && state->start > last + 1)
1818                         break;
1819                 if (state->end >= cur_start && (state->state & bits) == bits) {
1820                         total_bytes += min(search_end, state->end) + 1 -
1821                                        max(cur_start, state->start);
1822                         if (total_bytes >= max_bytes)
1823                                 break;
1824                         if (!found) {
1825                                 *start = max(cur_start, state->start);
1826                                 found = 1;
1827                         }
1828                         last = state->end;
1829                 } else if (contig && found) {
1830                         break;
1831                 }
1832                 node = rb_next(node);
1833                 if (!node)
1834                         break;
1835         }
1836 out:
1837         spin_unlock(&tree->lock);
1838         return total_bytes;
1839 }
1840 
1841 /*
1842  * set the private field for a given byte offset in the tree.  If there isn't
1843  * an extent_state there already, this does nothing.
1844  */
1845 static noinline int set_state_failrec(struct extent_io_tree *tree, u64 start,
1846                 struct io_failure_record *failrec)
1847 {
1848         struct rb_node *node;
1849         struct extent_state *state;
1850         int ret = 0;
1851 
1852         spin_lock(&tree->lock);
1853         /*
1854          * this search will find all the extents that end after
1855          * our range starts.
1856          */
1857         node = tree_search(tree, start);
1858         if (!node) {
1859                 ret = -ENOENT;
1860                 goto out;
1861         }
1862         state = rb_entry(node, struct extent_state, rb_node);
1863         if (state->start != start) {
1864                 ret = -ENOENT;
1865                 goto out;
1866         }
1867         state->failrec = failrec;
1868 out:
1869         spin_unlock(&tree->lock);
1870         return ret;
1871 }
1872 
1873 static noinline int get_state_failrec(struct extent_io_tree *tree, u64 start,
1874                 struct io_failure_record **failrec)
1875 {
1876         struct rb_node *node;
1877         struct extent_state *state;
1878         int ret = 0;
1879 
1880         spin_lock(&tree->lock);
1881         /*
1882          * this search will find all the extents that end after
1883          * our range starts.
1884          */
1885         node = tree_search(tree, start);
1886         if (!node) {
1887                 ret = -ENOENT;
1888                 goto out;
1889         }
1890         state = rb_entry(node, struct extent_state, rb_node);
1891         if (state->start != start) {
1892                 ret = -ENOENT;
1893                 goto out;
1894         }
1895         *failrec = state->failrec;
1896 out:
1897         spin_unlock(&tree->lock);
1898         return ret;
1899 }
1900 
1901 /*
1902  * searches a range in the state tree for a given mask.
1903  * If 'filled' == 1, this returns 1 only if every extent in the tree
1904  * has the bits set.  Otherwise, 1 is returned if any bit in the
1905  * range is found set.
1906  */
1907 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
1908                    unsigned bits, int filled, struct extent_state *cached)
1909 {
1910         struct extent_state *state = NULL;
1911         struct rb_node *node;
1912         int bitset = 0;
1913 
1914         spin_lock(&tree->lock);
1915         if (cached && extent_state_in_tree(cached) && cached->start <= start &&
1916             cached->end > start)
1917                 node = &cached->rb_node;
1918         else
1919                 node = tree_search(tree, start);
1920         while (node && start <= end) {
1921                 state = rb_entry(node, struct extent_state, rb_node);
1922 
1923                 if (filled && state->start > start) {
1924                         bitset = 0;
1925                         break;
1926                 }
1927 
1928                 if (state->start > end)
1929                         break;
1930 
1931                 if (state->state & bits) {
1932                         bitset = 1;
1933                         if (!filled)
1934                                 break;
1935                 } else if (filled) {
1936                         bitset = 0;
1937                         break;
1938                 }
1939 
1940                 if (state->end == (u64)-1)
1941                         break;
1942 
1943                 start = state->end + 1;
1944                 if (start > end)
1945                         break;
1946                 node = rb_next(node);
1947                 if (!node) {
1948                         if (filled)
1949                                 bitset = 0;
1950                         break;
1951                 }
1952         }
1953         spin_unlock(&tree->lock);
1954         return bitset;
1955 }
1956 
1957 /*
1958  * helper function to set a given page up to date if all the
1959  * extents in the tree for that page are up to date
1960  */
1961 static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
1962 {
1963         u64 start = page_offset(page);
1964         u64 end = start + PAGE_SIZE - 1;
1965         if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
1966                 SetPageUptodate(page);
1967 }
1968 
1969 int free_io_failure(struct inode *inode, struct io_failure_record *rec)
1970 {
1971         int ret;
1972         int err = 0;
1973         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
1974 
1975         set_state_failrec(failure_tree, rec->start, NULL);
1976         ret = clear_extent_bits(failure_tree, rec->start,
1977                                 rec->start + rec->len - 1,
1978                                 EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
1979         if (ret)
1980                 err = ret;
1981 
1982         ret = clear_extent_bits(&BTRFS_I(inode)->io_tree, rec->start,
1983                                 rec->start + rec->len - 1,
1984                                 EXTENT_DAMAGED, GFP_NOFS);
1985         if (ret && !err)
1986                 err = ret;
1987 
1988         kfree(rec);
1989         return err;
1990 }
1991 
1992 /*
1993  * this bypasses the standard btrfs submit functions deliberately, as
1994  * the standard behavior is to write all copies in a raid setup. here we only
1995  * want to write the one bad copy. so we do the mapping for ourselves and issue
1996  * submit_bio directly.
1997  * to avoid any synchronization issues, wait for the data after writing, which
1998  * actually prevents the read that triggered the error from finishing.
1999  * currently, there can be no more than two copies of every data bit. thus,
2000  * exactly one rewrite is required.
2001  */
2002 int repair_io_failure(struct inode *inode, u64 start, u64 length, u64 logical,
2003                       struct page *page, unsigned int pg_offset, int mirror_num)
2004 {
2005         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2006         struct bio *bio;
2007         struct btrfs_device *dev;
2008         u64 map_length = 0;
2009         u64 sector;
2010         struct btrfs_bio *bbio = NULL;
2011         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
2012         int ret;
2013 
2014         ASSERT(!(fs_info->sb->s_flags & MS_RDONLY));
2015         BUG_ON(!mirror_num);
2016 
2017         /* we can't repair anything in raid56 yet */
2018         if (btrfs_is_parity_mirror(map_tree, logical, length, mirror_num))
2019                 return 0;
2020 
2021         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2022         if (!bio)
2023                 return -EIO;
2024         bio->bi_iter.bi_size = 0;
2025         map_length = length;
2026 
2027         ret = btrfs_map_block(fs_info, WRITE, logical,
2028                               &map_length, &bbio, mirror_num);
2029         if (ret) {
2030                 bio_put(bio);
2031                 return -EIO;
2032         }
2033         BUG_ON(mirror_num != bbio->mirror_num);
2034         sector = bbio->stripes[mirror_num-1].physical >> 9;
2035         bio->bi_iter.bi_sector = sector;
2036         dev = bbio->stripes[mirror_num-1].dev;
2037         btrfs_put_bbio(bbio);
2038         if (!dev || !dev->bdev || !dev->writeable) {
2039                 bio_put(bio);
2040                 return -EIO;
2041         }
2042         bio->bi_bdev = dev->bdev;
2043         bio_add_page(bio, page, length, pg_offset);
2044 
2045         if (btrfsic_submit_bio_wait(WRITE_SYNC, bio)) {
2046                 /* try to remap that extent elsewhere? */
2047                 bio_put(bio);
2048                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
2049                 return -EIO;
2050         }
2051 
2052         btrfs_info_rl_in_rcu(fs_info,
2053                 "read error corrected: ino %llu off %llu (dev %s sector %llu)",
2054                                   btrfs_ino(inode), start,
2055                                   rcu_str_deref(dev->name), sector);
2056         bio_put(bio);
2057         return 0;
2058 }
2059 
2060 int repair_eb_io_failure(struct btrfs_root *root, struct extent_buffer *eb,
2061                          int mirror_num)
2062 {
2063         u64 start = eb->start;
2064         unsigned long i, num_pages = num_extent_pages(eb->start, eb->len);
2065         int ret = 0;
2066 
2067         if (root->fs_info->sb->s_flags & MS_RDONLY)
2068                 return -EROFS;
2069 
2070         for (i = 0; i < num_pages; i++) {
2071                 struct page *p = eb->pages[i];
2072 
2073                 ret = repair_io_failure(root->fs_info->btree_inode, start,
2074                                         PAGE_SIZE, start, p,
2075                                         start - page_offset(p), mirror_num);
2076                 if (ret)
2077                         break;
2078                 start += PAGE_SIZE;
2079         }
2080 
2081         return ret;
2082 }
2083 
2084 /*
2085  * each time an IO finishes, we do a fast check in the IO failure tree
2086  * to see if we need to process or clean up an io_failure_record
2087  */
2088 int clean_io_failure(struct inode *inode, u64 start, struct page *page,
2089                      unsigned int pg_offset)
2090 {
2091         u64 private;
2092         struct io_failure_record *failrec;
2093         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2094         struct extent_state *state;
2095         int num_copies;
2096         int ret;
2097 
2098         private = 0;
2099         ret = count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
2100                                 (u64)-1, 1, EXTENT_DIRTY, 0);
2101         if (!ret)
2102                 return 0;
2103 
2104         ret = get_state_failrec(&BTRFS_I(inode)->io_failure_tree, start,
2105                         &failrec);
2106         if (ret)
2107                 return 0;
2108 
2109         BUG_ON(!failrec->this_mirror);
2110 
2111         if (failrec->in_validation) {
2112                 /* there was no real error, just free the record */
2113                 pr_debug("clean_io_failure: freeing dummy error at %llu\n",
2114                          failrec->start);
2115                 goto out;
2116         }
2117         if (fs_info->sb->s_flags & MS_RDONLY)
2118                 goto out;
2119 
2120         spin_lock(&BTRFS_I(inode)->io_tree.lock);
2121         state = find_first_extent_bit_state(&BTRFS_I(inode)->io_tree,
2122                                             failrec->start,
2123                                             EXTENT_LOCKED);
2124         spin_unlock(&BTRFS_I(inode)->io_tree.lock);
2125 
2126         if (state && state->start <= failrec->start &&
2127             state->end >= failrec->start + failrec->len - 1) {
2128                 num_copies = btrfs_num_copies(fs_info, failrec->logical,
2129                                               failrec->len);
2130                 if (num_copies > 1)  {
2131                         repair_io_failure(inode, start, failrec->len,
2132                                           failrec->logical, page,
2133                                           pg_offset, failrec->failed_mirror);
2134                 }
2135         }
2136 
2137 out:
2138         free_io_failure(inode, failrec);
2139 
2140         return 0;
2141 }
2142 
2143 /*
2144  * Can be called when
2145  * - hold extent lock
2146  * - under ordered extent
2147  * - the inode is freeing
2148  */
2149 void btrfs_free_io_failure_record(struct inode *inode, u64 start, u64 end)
2150 {
2151         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2152         struct io_failure_record *failrec;
2153         struct extent_state *state, *next;
2154 
2155         if (RB_EMPTY_ROOT(&failure_tree->state))
2156                 return;
2157 
2158         spin_lock(&failure_tree->lock);
2159         state = find_first_extent_bit_state(failure_tree, start, EXTENT_DIRTY);
2160         while (state) {
2161                 if (state->start > end)
2162                         break;
2163 
2164                 ASSERT(state->end <= end);
2165 
2166                 next = next_state(state);
2167 
2168                 failrec = state->failrec;
2169                 free_extent_state(state);
2170                 kfree(failrec);
2171 
2172                 state = next;
2173         }
2174         spin_unlock(&failure_tree->lock);
2175 }
2176 
2177 int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
2178                 struct io_failure_record **failrec_ret)
2179 {
2180         struct io_failure_record *failrec;
2181         struct extent_map *em;
2182         struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2183         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2184         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2185         int ret;
2186         u64 logical;
2187 
2188         ret = get_state_failrec(failure_tree, start, &failrec);
2189         if (ret) {
2190                 failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
2191                 if (!failrec)
2192                         return -ENOMEM;
2193 
2194                 failrec->start = start;
2195                 failrec->len = end - start + 1;
2196                 failrec->this_mirror = 0;
2197                 failrec->bio_flags = 0;
2198                 failrec->in_validation = 0;
2199 
2200                 read_lock(&em_tree->lock);
2201                 em = lookup_extent_mapping(em_tree, start, failrec->len);
2202                 if (!em) {
2203                         read_unlock(&em_tree->lock);
2204                         kfree(failrec);
2205                         return -EIO;
2206                 }
2207 
2208                 if (em->start > start || em->start + em->len <= start) {
2209                         free_extent_map(em);
2210                         em = NULL;
2211                 }
2212                 read_unlock(&em_tree->lock);
2213                 if (!em) {
2214                         kfree(failrec);
2215                         return -EIO;
2216                 }
2217 
2218                 logical = start - em->start;
2219                 logical = em->block_start + logical;
2220                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2221                         logical = em->block_start;
2222                         failrec->bio_flags = EXTENT_BIO_COMPRESSED;
2223                         extent_set_compress_type(&failrec->bio_flags,
2224                                                  em->compress_type);
2225                 }
2226 
2227                 pr_debug("Get IO Failure Record: (new) logical=%llu, start=%llu, len=%llu\n",
2228                          logical, start, failrec->len);
2229 
2230                 failrec->logical = logical;
2231                 free_extent_map(em);
2232 
2233                 /* set the bits in the private failure tree */
2234                 ret = set_extent_bits(failure_tree, start, end,
2235                                         EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
2236                 if (ret >= 0)
2237                         ret = set_state_failrec(failure_tree, start, failrec);
2238                 /* set the bits in the inode's tree */
2239                 if (ret >= 0)
2240                         ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED,
2241                                                 GFP_NOFS);
2242                 if (ret < 0) {
2243                         kfree(failrec);
2244                         return ret;
2245                 }
2246         } else {
2247                 pr_debug("Get IO Failure Record: (found) logical=%llu, start=%llu, len=%llu, validation=%d\n",
2248                          failrec->logical, failrec->start, failrec->len,
2249                          failrec->in_validation);
2250                 /*
2251                  * when data can be on disk more than twice, add to failrec here
2252                  * (e.g. with a list for failed_mirror) to make
2253                  * clean_io_failure() clean all those errors at once.
2254                  */
2255         }
2256 
2257         *failrec_ret = failrec;
2258 
2259         return 0;
2260 }
2261 
2262 int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
2263                            struct io_failure_record *failrec, int failed_mirror)
2264 {
2265         int num_copies;
2266 
2267         num_copies = btrfs_num_copies(BTRFS_I(inode)->root->fs_info,
2268                                       failrec->logical, failrec->len);
2269         if (num_copies == 1) {
2270                 /*
2271                  * we only have a single copy of the data, so don't bother with
2272                  * all the retry and error correction code that follows. no
2273                  * matter what the error is, it is very likely to persist.
2274                  */
2275                 pr_debug("Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d\n",
2276                          num_copies, failrec->this_mirror, failed_mirror);
2277                 return 0;
2278         }
2279 
2280         /*
2281          * there are two premises:
2282          *      a) deliver good data to the caller
2283          *      b) correct the bad sectors on disk
2284          */
2285         if (failed_bio->bi_vcnt > 1) {
2286                 /*
2287                  * to fulfill b), we need to know the exact failing sectors, as
2288                  * we don't want to rewrite any more than the failed ones. thus,
2289                  * we need separate read requests for the failed bio
2290                  *
2291                  * if the following BUG_ON triggers, our validation request got
2292                  * merged. we need separate requests for our algorithm to work.
2293                  */
2294                 BUG_ON(failrec->in_validation);
2295                 failrec->in_validation = 1;
2296                 failrec->this_mirror = failed_mirror;
2297         } else {
2298                 /*
2299                  * we're ready to fulfill a) and b) alongside. get a good copy
2300                  * of the failed sector and if we succeed, we have setup
2301                  * everything for repair_io_failure to do the rest for us.
2302                  */
2303                 if (failrec->in_validation) {
2304                         BUG_ON(failrec->this_mirror != failed_mirror);
2305                         failrec->in_validation = 0;
2306                         failrec->this_mirror = 0;
2307                 }
2308                 failrec->failed_mirror = failed_mirror;
2309                 failrec->this_mirror++;
2310                 if (failrec->this_mirror == failed_mirror)
2311                         failrec->this_mirror++;
2312         }
2313 
2314         if (failrec->this_mirror > num_copies) {
2315                 pr_debug("Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d\n",
2316                          num_copies, failrec->this_mirror, failed_mirror);
2317                 return 0;
2318         }
2319 
2320         return 1;
2321 }
2322 
2323 
2324 struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
2325                                     struct io_failure_record *failrec,
2326                                     struct page *page, int pg_offset, int icsum,
2327                                     bio_end_io_t *endio_func, void *data)
2328 {
2329         struct bio *bio;
2330         struct btrfs_io_bio *btrfs_failed_bio;
2331         struct btrfs_io_bio *btrfs_bio;
2332 
2333         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2334         if (!bio)
2335                 return NULL;
2336 
2337         bio->bi_end_io = endio_func;
2338         bio->bi_iter.bi_sector = failrec->logical >> 9;
2339         bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
2340         bio->bi_iter.bi_size = 0;
2341         bio->bi_private = data;
2342 
2343         btrfs_failed_bio = btrfs_io_bio(failed_bio);
2344         if (btrfs_failed_bio->csum) {
2345                 struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2346                 u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
2347 
2348                 btrfs_bio = btrfs_io_bio(bio);
2349                 btrfs_bio->csum = btrfs_bio->csum_inline;
2350                 icsum *= csum_size;
2351                 memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + icsum,
2352                        csum_size);
2353         }
2354 
2355         bio_add_page(bio, page, failrec->len, pg_offset);
2356 
2357         return bio;
2358 }
2359 
2360 /*
2361  * this is a generic handler for readpage errors (default
2362  * readpage_io_failed_hook). if other copies exist, read those and write back
2363  * good data to the failed position. does not investigate in remapping the
2364  * failed extent elsewhere, hoping the device will be smart enough to do this as
2365  * needed
2366  */
2367 
2368 static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
2369                               struct page *page, u64 start, u64 end,
2370                               int failed_mirror)
2371 {
2372         struct io_failure_record *failrec;
2373         struct inode *inode = page->mapping->host;
2374         struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2375         struct bio *bio;
2376         int read_mode;
2377         int ret;
2378 
2379         BUG_ON(failed_bio->bi_rw & REQ_WRITE);
2380 
2381         ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
2382         if (ret)
2383                 return ret;
2384 
2385         ret = btrfs_check_repairable(inode, failed_bio, failrec, failed_mirror);
2386         if (!ret) {
2387                 free_io_failure(inode, failrec);
2388                 return -EIO;
2389         }
2390 
2391         if (failed_bio->bi_vcnt > 1)
2392                 read_mode = READ_SYNC | REQ_FAILFAST_DEV;
2393         else
2394                 read_mode = READ_SYNC;
2395 
2396         phy_offset >>= inode->i_sb->s_blocksize_bits;
2397         bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
2398                                       start - page_offset(page),
2399                                       (int)phy_offset, failed_bio->bi_end_io,
2400                                       NULL);
2401         if (!bio) {
2402                 free_io_failure(inode, failrec);
2403                 return -EIO;
2404         }
2405 
2406         pr_debug("Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d\n",
2407                  read_mode, failrec->this_mirror, failrec->in_validation);
2408 
2409         ret = tree->ops->submit_bio_hook(inode, read_mode, bio,
2410                                          failrec->this_mirror,
2411                                          failrec->bio_flags, 0);
2412         if (ret) {
2413                 free_io_failure(inode, failrec);
2414                 bio_put(bio);
2415         }
2416 
2417         return ret;
2418 }
2419 
2420 /* lots and lots of room for performance fixes in the end_bio funcs */
2421 
2422 void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
2423 {
2424         int uptodate = (err == 0);
2425         struct extent_io_tree *tree;
2426         int ret = 0;
2427 
2428         tree = &BTRFS_I(page->mapping->host)->io_tree;
2429 
2430         if (tree->ops && tree->ops->writepage_end_io_hook) {
2431                 ret = tree->ops->writepage_end_io_hook(page, start,
2432                                                end, NULL, uptodate);
2433                 if (ret)
2434                         uptodate = 0;
2435         }
2436 
2437         if (!uptodate) {
2438                 ClearPageUptodate(page);
2439                 SetPageError(page);
2440                 ret = ret < 0 ? ret : -EIO;
2441                 mapping_set_error(page->mapping, ret);
2442         }
2443 }
2444 
2445 /*
2446  * after a writepage IO is done, we need to:
2447  * clear the uptodate bits on error
2448  * clear the writeback bits in the extent tree for this IO
2449  * end_page_writeback if the page has no more pending IO
2450  *
2451  * Scheduling is not allowed, so the extent state tree is expected
2452  * to have one and only one object corresponding to this IO.
2453  */
2454 static void end_bio_extent_writepage(struct bio *bio)
2455 {
2456         struct bio_vec *bvec;
2457         u64 start;
2458         u64 end;
2459         int i;
2460 
2461         bio_for_each_segment_all(bvec, bio, i) {
2462                 struct page *page = bvec->bv_page;
2463 
2464                 /* We always issue full-page reads, but if some block
2465                  * in a page fails to read, blk_update_request() will
2466                  * advance bv_offset and adjust bv_len to compensate.
2467                  * Print a warning for nonzero offsets, and an error
2468                  * if they don't add up to a full page.  */
2469                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2470                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2471                                 btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2472                                    "partial page write in btrfs with offset %u and length %u",
2473                                         bvec->bv_offset, bvec->bv_len);
2474                         else
2475                                 btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2476                                    "incomplete page write in btrfs with offset %u and "
2477                                    "length %u",
2478                                         bvec->bv_offset, bvec->bv_len);
2479                 }
2480 
2481                 start = page_offset(page);
2482                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2483 
2484                 end_extent_writepage(page, bio->bi_error, start, end);
2485                 end_page_writeback(page);
2486         }
2487 
2488         bio_put(bio);
2489 }
2490 
2491 static void
2492 endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
2493                               int uptodate)
2494 {
2495         struct extent_state *cached = NULL;
2496         u64 end = start + len - 1;
2497 
2498         if (uptodate && tree->track_uptodate)
2499                 set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
2500         unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
2501 }
2502 
2503 /*
2504  * after a readpage IO is done, we need to:
2505  * clear the uptodate bits on error
2506  * set the uptodate bits if things worked
2507  * set the page up to date if all extents in the tree are uptodate
2508  * clear the lock bit in the extent tree
2509  * unlock the page if there are no other extents locked for it
2510  *
2511  * Scheduling is not allowed, so the extent state tree is expected
2512  * to have one and only one object corresponding to this IO.
2513  */
2514 static void end_bio_extent_readpage(struct bio *bio)
2515 {
2516         struct bio_vec *bvec;
2517         int uptodate = !bio->bi_error;
2518         struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
2519         struct extent_io_tree *tree;
2520         u64 offset = 0;
2521         u64 start;
2522         u64 end;
2523         u64 len;
2524         u64 extent_start = 0;
2525         u64 extent_len = 0;
2526         int mirror;
2527         int ret;
2528         int i;
2529 
2530         bio_for_each_segment_all(bvec, bio, i) {
2531                 struct page *page = bvec->bv_page;
2532                 struct inode *inode = page->mapping->host;
2533 
2534                 pr_debug("end_bio_extent_readpage: bi_sector=%llu, err=%d, "
2535                          "mirror=%u\n", (u64)bio->bi_iter.bi_sector,
2536                          bio->bi_error, io_bio->mirror_num);
2537                 tree = &BTRFS_I(inode)->io_tree;
2538 
2539                 /* We always issue full-page reads, but if some block
2540                  * in a page fails to read, blk_update_request() will
2541                  * advance bv_offset and adjust bv_len to compensate.
2542                  * Print a warning for nonzero offsets, and an error
2543                  * if they don't add up to a full page.  */
2544                 if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
2545                         if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
2546                                 btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2547                                    "partial page read in btrfs with offset %u and length %u",
2548                                         bvec->bv_offset, bvec->bv_len);
2549                         else
2550                                 btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2551                                    "incomplete page read in btrfs with offset %u and "
2552                                    "length %u",
2553                                         bvec->bv_offset, bvec->bv_len);
2554                 }
2555 
2556                 start = page_offset(page);
2557                 end = start + bvec->bv_offset + bvec->bv_len - 1;
2558                 len = bvec->bv_len;
2559 
2560                 mirror = io_bio->mirror_num;
2561                 if (likely(uptodate && tree->ops &&
2562                            tree->ops->readpage_end_io_hook)) {
2563                         ret = tree->ops->readpage_end_io_hook(io_bio, offset,
2564                                                               page, start, end,
2565                                                               mirror);
2566                         if (ret)
2567                                 uptodate = 0;
2568                         else
2569                                 clean_io_failure(inode, start, page, 0);
2570                 }
2571 
2572                 if (likely(uptodate))
2573                         goto readpage_ok;
2574 
2575                 if (tree->ops && tree->ops->readpage_io_failed_hook) {
2576                         ret = tree->ops->readpage_io_failed_hook(page, mirror);
2577                         if (!ret && !bio->bi_error)
2578                                 uptodate = 1;
2579                 } else {
2580                         /*
2581                          * The generic bio_readpage_error handles errors the
2582                          * following way: If possible, new read requests are
2583                          * created and submitted and will end up in
2584                          * end_bio_extent_readpage as well (if we're lucky, not
2585                          * in the !uptodate case). In that case it returns 0 and
2586                          * we just go on with the next page in our bio. If it
2587                          * can't handle the error it will return -EIO and we
2588                          * remain responsible for that page.
2589                          */
2590                         ret = bio_readpage_error(bio, offset, page, start, end,
2591                                                  mirror);
2592                         if (ret == 0) {
2593                                 uptodate = !bio->bi_error;
2594                                 offset += len;
2595                                 continue;
2596                         }
2597                 }
2598 readpage_ok:
2599                 if (likely(uptodate)) {
2600                         loff_t i_size = i_size_read(inode);
2601                         pgoff_t end_index = i_size >> PAGE_SHIFT;
2602                         unsigned off;
2603 
2604                         /* Zero out the end if this page straddles i_size */
2605                         off = i_size & (PAGE_SIZE-1);
2606                         if (page->index == end_index && off)
2607                                 zero_user_segment(page, off, PAGE_SIZE);
2608                         SetPageUptodate(page);
2609                 } else {
2610                         ClearPageUptodate(page);
2611                         SetPageError(page);
2612                 }
2613                 unlock_page(page);
2614                 offset += len;
2615 
2616                 if (unlikely(!uptodate)) {
2617                         if (extent_len) {
2618                                 endio_readpage_release_extent(tree,
2619                                                               extent_start,
2620                                                               extent_len, 1);
2621                                 extent_start = 0;
2622                                 extent_len = 0;
2623                         }
2624                         endio_readpage_release_extent(tree, start,
2625                                                       end - start + 1, 0);
2626                 } else if (!extent_len) {
2627                         extent_start = start;
2628                         extent_len = end + 1 - start;
2629                 } else if (extent_start + extent_len == start) {
2630                         extent_len += end + 1 - start;
2631                 } else {
2632                         endio_readpage_release_extent(tree, extent_start,
2633                                                       extent_len, uptodate);
2634                         extent_start = start;
2635                         extent_len = end + 1 - start;
2636                 }
2637         }
2638 
2639         if (extent_len)
2640                 endio_readpage_release_extent(tree, extent_start, extent_len,
2641                                               uptodate);
2642         if (io_bio->end_io)
2643                 io_bio->end_io(io_bio, bio->bi_error);
2644         bio_put(bio);
2645 }
2646 
2647 /*
2648  * this allocates from the btrfs_bioset.  We're returning a bio right now
2649  * but you can call btrfs_io_bio for the appropriate container_of magic
2650  */
2651 struct bio *
2652 btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
2653                 gfp_t gfp_flags)
2654 {
2655         struct btrfs_io_bio *btrfs_bio;
2656         struct bio *bio;
2657 
2658         bio = bio_alloc_bioset(gfp_flags, nr_vecs, btrfs_bioset);
2659 
2660         if (bio == NULL && (current->flags & PF_MEMALLOC)) {
2661                 while (!bio && (nr_vecs /= 2)) {
2662                         bio = bio_alloc_bioset(gfp_flags,
2663                                                nr_vecs, btrfs_bioset);
2664                 }
2665         }
2666 
2667         if (bio) {
2668                 bio->bi_bdev = bdev;
2669                 bio->bi_iter.bi_sector = first_sector;
2670                 btrfs_bio = btrfs_io_bio(bio);
2671                 btrfs_bio->csum = NULL;
2672                 btrfs_bio->csum_allocated = NULL;
2673                 btrfs_bio->end_io = NULL;
2674         }
2675         return bio;
2676 }
2677 
2678 struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
2679 {
2680         struct btrfs_io_bio *btrfs_bio;
2681         struct bio *new;
2682 
2683         new = bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
2684         if (new) {
2685                 btrfs_bio = btrfs_io_bio(new);
2686                 btrfs_bio->csum = NULL;
2687                 btrfs_bio->csum_allocated = NULL;
2688                 btrfs_bio->end_io = NULL;
2689 
2690 #ifdef CONFIG_BLK_CGROUP
2691                 /* FIXME, put this into bio_clone_bioset */
2692                 if (bio->bi_css)
2693                         bio_associate_blkcg(new, bio->bi_css);
2694 #endif
2695         }
2696         return new;
2697 }
2698 
2699 /* this also allocates from the btrfs_bioset */
2700 struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
2701 {
2702         struct btrfs_io_bio *btrfs_bio;
2703         struct bio *bio;
2704 
2705         bio = bio_alloc_bioset(gfp_mask, nr_iovecs, btrfs_bioset);
2706         if (bio) {
2707                 btrfs_bio = btrfs_io_bio(bio);
2708                 btrfs_bio->csum = NULL;
2709                 btrfs_bio->csum_allocated = NULL;
2710                 btrfs_bio->end_io = NULL;
2711         }
2712         return bio;
2713 }
2714 
2715 
2716 static int __must_check submit_one_bio(int rw, struct bio *bio,
2717                                        int mirror_num, unsigned long bio_flags)
2718 {
2719         int ret = 0;
2720         struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
2721         struct page *page = bvec->bv_page;
2722         struct extent_io_tree *tree = bio->bi_private;
2723         u64 start;
2724 
2725         start = page_offset(page) + bvec->bv_offset;
2726 
2727         bio->bi_private = NULL;
2728 
2729         bio_get(bio);
2730 
2731         if (tree->ops && tree->ops->submit_bio_hook)
2732                 ret = tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
2733                                            mirror_num, bio_flags, start);
2734         else
2735                 btrfsic_submit_bio(rw, bio);
2736 
2737         bio_put(bio);
2738         return ret;
2739 }
2740 
2741 static int merge_bio(int rw, struct extent_io_tree *tree, struct page *page,
2742                      unsigned long offset, size_t size, struct bio *bio,
2743                      unsigned long bio_flags)
2744 {
2745         int ret = 0;
2746         if (tree->ops && tree->ops->merge_bio_hook)
2747                 ret = tree->ops->merge_bio_hook(rw, page, offset, size, bio,
2748                                                 bio_flags);
2749         BUG_ON(ret < 0);
2750         return ret;
2751 
2752 }
2753 
2754 static int submit_extent_page(int rw, struct extent_io_tree *tree,
2755                               struct writeback_control *wbc,
2756                               struct page *page, sector_t sector,
2757                               size_t size, unsigned long offset,
2758                               struct block_device *bdev,
2759                               struct bio **bio_ret,
2760                               unsigned long max_pages,
2761                               bio_end_io_t end_io_func,
2762                               int mirror_num,
2763                               unsigned long prev_bio_flags,
2764                               unsigned long bio_flags,
2765                               bool force_bio_submit)
2766 {
2767         int ret = 0;
2768         struct bio *bio;
2769         int contig = 0;
2770         int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
2771         size_t page_size = min_t(size_t, size, PAGE_SIZE);
2772 
2773         if (bio_ret && *bio_ret) {
2774                 bio = *bio_ret;
2775                 if (old_compressed)
2776                         contig = bio->bi_iter.bi_sector == sector;
2777                 else
2778                         contig = bio_end_sector(bio) == sector;
2779 
2780                 if (prev_bio_flags != bio_flags || !contig ||
2781                     force_bio_submit ||
2782                     merge_bio(rw, tree, page, offset, page_size, bio, bio_flags) ||
2783                     bio_add_page(bio, page, page_size, offset) < page_size) {
2784                         ret = submit_one_bio(rw, bio, mirror_num,
2785                                              prev_bio_flags);
2786                         if (ret < 0) {
2787                                 *bio_ret = NULL;
2788                                 return ret;
2789                         }
2790                         bio = NULL;
2791                 } else {
2792                         if (wbc)
2793                                 wbc_account_io(wbc, page, page_size);
2794                         return 0;
2795                 }
2796         }
2797 
2798         bio = btrfs_bio_alloc(bdev, sector, BIO_MAX_PAGES,
2799                         GFP_NOFS | __GFP_HIGH);
2800         if (!bio)
2801                 return -ENOMEM;
2802 
2803         bio_add_page(bio, page, page_size, offset);
2804         bio->bi_end_io = end_io_func;
2805         bio->bi_private = tree;
2806         if (wbc) {
2807                 wbc_init_bio(wbc, bio);
2808                 wbc_account_io(wbc, page, page_size);
2809         }
2810 
2811         if (bio_ret)
2812                 *bio_ret = bio;
2813         else
2814                 ret = submit_one_bio(rw, bio, mirror_num, bio_flags);
2815 
2816         return ret;
2817 }
2818 
2819 static void attach_extent_buffer_page(struct extent_buffer *eb,
2820                                       struct page *page)
2821 {
2822         if (!PagePrivate(page)) {
2823                 SetPagePrivate(page);
2824                 get_page(page);
2825                 set_page_private(page, (unsigned long)eb);
2826         } else {
2827                 WARN_ON(page->private != (unsigned long)eb);
2828         }
2829 }
2830 
2831 void set_page_extent_mapped(struct page *page)
2832 {
2833         if (!PagePrivate(page)) {
2834                 SetPagePrivate(page);
2835                 get_page(page);
2836                 set_page_private(page, EXTENT_PAGE_PRIVATE);
2837         }
2838 }
2839 
2840 static struct extent_map *
2841 __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
2842                  u64 start, u64 len, get_extent_t *get_extent,
2843                  struct extent_map **em_cached)
2844 {
2845         struct extent_map *em;
2846 
2847         if (em_cached && *em_cached) {
2848                 em = *em_cached;
2849                 if (extent_map_in_tree(em) && start >= em->start &&
2850                     start < extent_map_end(em)) {
2851                         atomic_inc(&em->refs);
2852                         return em;
2853                 }
2854 
2855                 free_extent_map(em);
2856                 *em_cached = NULL;
2857         }
2858 
2859         em = get_extent(inode, page, pg_offset, start, len, 0);
2860         if (em_cached && !IS_ERR_OR_NULL(em)) {
2861                 BUG_ON(*em_cached);
2862                 atomic_inc(&em->refs);
2863                 *em_cached = em;
2864         }
2865         return em;
2866 }
2867 /*
2868  * basic readpage implementation.  Locked extent state structs are inserted
2869  * into the tree that are removed when the IO is done (by the end_io
2870  * handlers)
2871  * XXX JDM: This needs looking at to ensure proper page locking
2872  */
2873 static int __do_readpage(struct extent_io_tree *tree,
2874                          struct page *page,
2875                          get_extent_t *get_extent,
2876                          struct extent_map **em_cached,
2877                          struct bio **bio, int mirror_num,
2878                          unsigned long *bio_flags, int rw,
2879                          u64 *prev_em_start)
2880 {
2881         struct inode *inode = page->mapping->host;
2882         u64 start = page_offset(page);
2883         u64 page_end = start + PAGE_SIZE - 1;
2884         u64 end;
2885         u64 cur = start;
2886         u64 extent_offset;
2887         u64 last_byte = i_size_read(inode);
2888         u64 block_start;
2889         u64 cur_end;
2890         sector_t sector;
2891         struct extent_map *em;
2892         struct block_device *bdev;
2893         int ret;
2894         int nr = 0;
2895         size_t pg_offset = 0;
2896         size_t iosize;
2897         size_t disk_io_size;
2898         size_t blocksize = inode->i_sb->s_blocksize;
2899         unsigned long this_bio_flag = 0;
2900 
2901         set_page_extent_mapped(page);
2902 
2903         end = page_end;
2904         if (!PageUptodate(page)) {
2905                 if (cleancache_get_page(page) == 0) {
2906                         BUG_ON(blocksize != PAGE_SIZE);
2907                         unlock_extent(tree, start, end);
2908                         goto out;
2909                 }
2910         }
2911 
2912         if (page->index == last_byte >> PAGE_SHIFT) {
2913                 char *userpage;
2914                 size_t zero_offset = last_byte & (PAGE_SIZE - 1);
2915 
2916                 if (zero_offset) {
2917                         iosize = PAGE_SIZE - zero_offset;
2918                         userpage = kmap_atomic(page);
2919                         memset(userpage + zero_offset, 0, iosize);
2920                         flush_dcache_page(page);
2921                         kunmap_atomic(userpage);
2922                 }
2923         }
2924         while (cur <= end) {
2925                 unsigned long pnr = (last_byte >> PAGE_SHIFT) + 1;
2926                 bool force_bio_submit = false;
2927 
2928                 if (cur >= last_byte) {
2929                         char *userpage;
2930                         struct extent_state *cached = NULL;
2931 
2932                         iosize = PAGE_SIZE - pg_offset;
2933                         userpage = kmap_atomic(page);
2934                         memset(userpage + pg_offset, 0, iosize);
2935                         flush_dcache_page(page);
2936                         kunmap_atomic(userpage);
2937                         set_extent_uptodate(tree, cur, cur + iosize - 1,
2938                                             &cached, GFP_NOFS);
2939                         unlock_extent_cached(tree, cur,
2940                                              cur + iosize - 1,
2941                                              &cached, GFP_NOFS);
2942                         break;
2943                 }
2944                 em = __get_extent_map(inode, page, pg_offset, cur,
2945                                       end - cur + 1, get_extent, em_cached);
2946                 if (IS_ERR_OR_NULL(em)) {
2947                         SetPageError(page);
2948                         unlock_extent(tree, cur, end);
2949                         break;
2950                 }
2951                 extent_offset = cur - em->start;
2952                 BUG_ON(extent_map_end(em) <= cur);
2953                 BUG_ON(end < cur);
2954 
2955                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2956                         this_bio_flag |= EXTENT_BIO_COMPRESSED;
2957                         extent_set_compress_type(&this_bio_flag,
2958                                                  em->compress_type);
2959                 }
2960 
2961                 iosize = min(extent_map_end(em) - cur, end - cur + 1);
2962                 cur_end = min(extent_map_end(em) - 1, end);
2963                 iosize = ALIGN(iosize, blocksize);
2964                 if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
2965                         disk_io_size = em->block_len;
2966                         sector = em->block_start >> 9;
2967                 } else {
2968                         sector = (em->block_start + extent_offset) >> 9;
2969                         disk_io_size = iosize;
2970                 }
2971                 bdev = em->bdev;
2972                 block_start = em->block_start;
2973                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
2974                         block_start = EXTENT_MAP_HOLE;
2975 
2976                 /*
2977                  * If we have a file range that points to a compressed extent
2978                  * and it's followed by a consecutive file range that points to
2979                  * to the same compressed extent (possibly with a different
2980                  * offset and/or length, so it either points to the whole extent
2981                  * or only part of it), we must make sure we do not submit a
2982                  * single bio to populate the pages for the 2 ranges because
2983                  * this makes the compressed extent read zero out the pages
2984                  * belonging to the 2nd range. Imagine the following scenario:
2985                  *
2986                  *  File layout
2987                  *  [0 - 8K]                     [8K - 24K]
2988                  *    |                               |
2989                  *    |                               |
2990                  * points to extent X,         points to extent X,
2991                  * offset 4K, length of 8K     offset 0, length 16K
2992                  *
2993                  * [extent X, compressed length = 4K uncompressed length = 16K]
2994                  *
2995                  * If the bio to read the compressed extent covers both ranges,
2996                  * it will decompress extent X into the pages belonging to the
2997                  * first range and then it will stop, zeroing out the remaining
2998                  * pages that belong to the other range that points to extent X.
2999                  * So here we make sure we submit 2 bios, one for the first
3000                  * range and another one for the third range. Both will target
3001                  * the same physical extent from disk, but we can't currently
3002                  * make the compressed bio endio callback populate the pages
3003                  * for both ranges because each compressed bio is tightly
3004                  * coupled with a single extent map, and each range can have
3005                  * an extent map with a different offset value relative to the
3006                  * uncompressed data of our extent and different lengths. This
3007                  * is a corner case so we prioritize correctness over
3008                  * non-optimal behavior (submitting 2 bios for the same extent).
3009                  */
3010                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) &&
3011                     prev_em_start && *prev_em_start != (u64)-1 &&
3012                     *prev_em_start != em->orig_start)
3013                         force_bio_submit = true;
3014 
3015                 if (prev_em_start)
3016                         *prev_em_start = em->orig_start;
3017 
3018                 free_extent_map(em);
3019                 em = NULL;
3020 
3021                 /* we've found a hole, just zero and go on */
3022                 if (block_start == EXTENT_MAP_HOLE) {
3023                         char *userpage;
3024                         struct extent_state *cached = NULL;
3025 
3026                         userpage = kmap_atomic(page);
3027                         memset(userpage + pg_offset, 0, iosize);
3028                         flush_dcache_page(page);
3029                         kunmap_atomic(userpage);
3030 
3031                         set_extent_uptodate(tree, cur, cur + iosize - 1,
3032                                             &cached, GFP_NOFS);
3033                         unlock_extent_cached(tree, cur,
3034                                              cur + iosize - 1,
3035                                              &cached, GFP_NOFS);
3036                         cur = cur + iosize;
3037                         pg_offset += iosize;
3038                         continue;
3039                 }
3040                 /* the get_extent function already copied into the page */
3041                 if (test_range_bit(tree, cur, cur_end,
3042                                    EXTENT_UPTODATE, 1, NULL)) {
3043                         check_page_uptodate(tree, page);
3044                         unlock_extent(tree, cur, cur + iosize - 1);
3045                         cur = cur + iosize;
3046                         pg_offset += iosize;
3047                         continue;
3048                 }
3049                 /* we have an inline extent but it didn't get marked up
3050                  * to date.  Error out
3051                  */
3052                 if (block_start == EXTENT_MAP_INLINE) {
3053                         SetPageError(page);
3054                         unlock_extent(tree, cur, cur + iosize - 1);
3055                         cur = cur + iosize;
3056                         pg_offset += iosize;
3057                         continue;
3058                 }
3059 
3060                 pnr -= page->index;
3061                 ret = submit_extent_page(rw, tree, NULL, page,
3062                                          sector, disk_io_size, pg_offset,
3063                                          bdev, bio, pnr,
3064                                          end_bio_extent_readpage, mirror_num,
3065                                          *bio_flags,
3066                                          this_bio_flag,
3067                                          force_bio_submit);
3068                 if (!ret) {
3069                         nr++;
3070                         *bio_flags = this_bio_flag;
3071                 } else {
3072                         SetPageError(page);
3073                         unlock_extent(tree, cur, cur + iosize - 1);
3074                 }
3075                 cur = cur + iosize;
3076                 pg_offset += iosize;
3077         }
3078 out:
3079         if (!nr) {
3080                 if (!PageError(page))
3081                         SetPageUptodate(page);
3082                 unlock_page(page);
3083         }
3084         return 0;
3085 }
3086 
3087 static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
3088                                              struct page *pages[], int nr_pages,
3089                                              u64 start, u64 end,
3090                                              get_extent_t *get_extent,
3091                                              struct extent_map **em_cached,
3092                                              struct bio **bio, int mirror_num,
3093                                              unsigned long *bio_flags, int rw,
3094                                              u64 *prev_em_start)
3095 {
3096         struct inode *inode;
3097         struct btrfs_ordered_extent *ordered;
3098         int index;
3099 
3100         inode = pages[0]->mapping->host;
3101         while (1) {
3102                 lock_extent(tree, start, end);
3103                 ordered = btrfs_lookup_ordered_range(inode, start,
3104                                                      end - start + 1);
3105                 if (!ordered)
3106                         break;
3107                 unlock_extent(tree, start, end);
3108                 btrfs_start_ordered_extent(inode, ordered, 1);
3109                 btrfs_put_ordered_extent(ordered);
3110         }
3111 
3112         for (index = 0; index < nr_pages; index++) {
3113                 __do_readpage(tree, pages[index], get_extent, em_cached, bio,
3114                               mirror_num, bio_flags, rw, prev_em_start);
3115                 put_page(pages[index]);
3116         }
3117 }
3118 
3119 static void __extent_readpages(struct extent_io_tree *tree,
3120                                struct page *pages[],
3121                                int nr_pages, get_extent_t *get_extent,
3122                                struct extent_map **em_cached,
3123                                struct bio **bio, int mirror_num,
3124                                unsigned long *bio_flags, int rw,
3125                                u64 *prev_em_start)
3126 {
3127         u64 start = 0;
3128         u64 end = 0;
3129         u64 page_start;
3130         int index;
3131         int first_index = 0;
3132 
3133         for (index = 0; index < nr_pages; index++) {
3134                 page_start = page_offset(pages[index]);
3135                 if (!end) {
3136                         start = page_start;
3137                         end = start + PAGE_SIZE - 1;
3138                         first_index = index;
3139                 } else if (end + 1 == page_start) {
3140                         end += PAGE_SIZE;
3141                 } else {
3142                         __do_contiguous_readpages(tree, &pages[first_index],
3143                                                   index - first_index, start,
3144                                                   end, get_extent, em_cached,
3145                                                   bio, mirror_num, bio_flags,
3146                                                   rw, prev_em_start);
3147                         start = page_start;
3148                         end = start + PAGE_SIZE - 1;
3149                         first_index = index;
3150                 }
3151         }
3152 
3153         if (end)
3154                 __do_contiguous_readpages(tree, &pages[first_index],
3155                                           index - first_index, start,
3156                                           end, get_extent, em_cached, bio,
3157                                           mirror_num, bio_flags, rw,
3158                                           prev_em_start);
3159 }
3160 
3161 static int __extent_read_full_page(struct extent_io_tree *tree,
3162                                    struct page *page,
3163                                    get_extent_t *get_extent,
3164                                    struct bio **bio, int mirror_num,
3165                                    unsigned long *bio_flags, int rw)
3166 {
3167         struct inode *inode = page->mapping->host;
3168         struct btrfs_ordered_extent *ordered;
3169         u64 start = page_offset(page);
3170         u64 end = start + PAGE_SIZE - 1;
3171         int ret;
3172 
3173         while (1) {
3174                 lock_extent(tree, start, end);
3175                 ordered = btrfs_lookup_ordered_range(inode, start,
3176                                                 PAGE_SIZE);
3177                 if (!ordered)
3178                         break;
3179                 unlock_extent(tree, start, end);
3180                 btrfs_start_ordered_extent(inode, ordered, 1);
3181                 btrfs_put_ordered_extent(ordered);
3182         }
3183 
3184         ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
3185                             bio_flags, rw, NULL);
3186         return ret;
3187 }
3188 
3189 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
3190                             get_extent_t *get_extent, int mirror_num)
3191 {
3192         struct bio *bio = NULL;
3193         unsigned long bio_flags = 0;
3194         int ret;
3195 
3196         ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
3197                                       &bio_flags, READ);
3198         if (bio)
3199                 ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
3200         return ret;
3201 }
3202 
3203 static noinline void update_nr_written(struct page *page,
3204                                       struct writeback_control *wbc,
3205                                       unsigned long nr_written)
3206 {
3207         wbc->nr_to_write -= nr_written;
3208         if (wbc->range_cyclic || (wbc->nr_to_write > 0 &&
3209             wbc->range_start == 0 && wbc->range_end == LLONG_MAX))
3210                 page->mapping->writeback_index = page->index + nr_written;
3211 }
3212 
3213 /*
3214  * helper for __extent_writepage, doing all of the delayed allocation setup.
3215  *
3216  * This returns 1 if our fill_delalloc function did all the work required
3217  * to write the page (copy into inline extent).  In this case the IO has
3218  * been started and the page is already unlocked.
3219  *
3220  * This returns 0 if all went well (page still locked)
3221  * This returns < 0 if there were errors (page still locked)
3222  */
3223 static noinline_for_stack int writepage_delalloc(struct inode *inode,
3224                               struct page *page, struct writeback_control *wbc,
3225                               struct extent_page_data *epd,
3226                               u64 delalloc_start,
3227                               unsigned long *nr_written)
3228 {
3229         struct extent_io_tree *tree = epd->tree;
3230         u64 page_end = delalloc_start + PAGE_SIZE - 1;
3231         u64 nr_delalloc;
3232         u64 delalloc_to_write = 0;
3233         u64 delalloc_end = 0;
3234         int ret;
3235         int page_started = 0;
3236 
3237         if (epd->extent_locked || !tree->ops || !tree->ops->fill_delalloc)
3238                 return 0;
3239 
3240         while (delalloc_end < page_end) {
3241                 nr_delalloc = find_lock_delalloc_range(inode, tree,
3242                                                page,
3243                                                &delalloc_start,
3244                                                &delalloc_end,
3245                                                BTRFS_MAX_EXTENT_SIZE);
3246                 if (nr_delalloc == 0) {
3247                         delalloc_start = delalloc_end + 1;
3248                         continue;
3249                 }
3250                 ret = tree->ops->fill_delalloc(inode, page,
3251                                                delalloc_start,
3252                                                delalloc_end,
3253                                                &page_started,
3254                                                nr_written);
3255                 /* File system has been set read-only */
3256                 if (ret) {
3257                         SetPageError(page);
3258                         /* fill_delalloc should be return < 0 for error
3259                          * but just in case, we use > 0 here meaning the
3260                          * IO is started, so we don't want to return > 0
3261                          * unless things are going well.
3262                          */
3263                         ret = ret < 0 ? ret : -EIO;
3264                         goto done;
3265                 }
3266                 /*
3267                  * delalloc_end is already one less than the total length, so
3268                  * we don't subtract one from PAGE_SIZE
3269                  */
3270                 delalloc_to_write += (delalloc_end - delalloc_start +
3271                                       PAGE_SIZE) >> PAGE_SHIFT;
3272                 delalloc_start = delalloc_end + 1;
3273         }
3274         if (wbc->nr_to_write < delalloc_to_write) {
3275                 int thresh = 8192;
3276 
3277                 if (delalloc_to_write < thresh * 2)
3278                         thresh = delalloc_to_write;
3279                 wbc->nr_to_write = min_t(u64, delalloc_to_write,
3280                                          thresh);
3281         }
3282 
3283         /* did the fill delalloc function already unlock and start
3284          * the IO?
3285          */
3286         if (page_started) {
3287                 /*
3288                  * we've unlocked the page, so we can't update
3289                  * the mapping's writeback index, just update
3290                  * nr_to_write.
3291                  */
3292                 wbc->nr_to_write -= *nr_written;
3293                 return 1;
3294         }
3295 
3296         ret = 0;
3297 
3298 done:
3299         return ret;
3300 }
3301 
3302 /*
3303  * helper for __extent_writepage.  This calls the writepage start hooks,
3304  * and does the loop to map the page into extents and bios.
3305  *
3306  * We return 1 if the IO is started and the page is unlocked,
3307  * 0 if all went well (page still locked)
3308  * < 0 if there were errors (page still locked)
3309  */
3310 static noinline_for_stack int __extent_writepage_io(struct inode *inode,
3311                                  struct page *page,
3312                                  struct writeback_control *wbc,
3313                                  struct extent_page_data *epd,
3314                                  loff_t i_size,
3315                                  unsigned long nr_written,
3316                                  int write_flags, int *nr_ret)
3317 {
3318         struct extent_io_tree *tree = epd->tree;
3319         u64 start = page_offset(page);
3320         u64 page_end = start + PAGE_SIZE - 1;
3321         u64 end;
3322         u64 cur = start;
3323         u64 extent_offset;
3324         u64 block_start;
3325         u64 iosize;
3326         sector_t sector;
3327         struct extent_state *cached_state = NULL;
3328         struct extent_map *em;
3329         struct block_device *bdev;
3330         size_t pg_offset = 0;
3331         size_t blocksize;
3332         int ret = 0;
3333         int nr = 0;
3334         bool compressed;
3335 
3336         if (tree->ops && tree->ops->writepage_start_hook) {
3337                 ret = tree->ops->writepage_start_hook(page, start,
3338                                                       page_end);
3339                 if (ret) {
3340                         /* Fixup worker will requeue */
3341                         if (ret == -EBUSY)
3342                                 wbc->pages_skipped++;
3343                         else
3344                                 redirty_page_for_writepage(wbc, page);
3345 
3346                         update_nr_written(page, wbc, nr_written);
3347                         unlock_page(page);
3348                         ret = 1;
3349                         goto done_unlocked;
3350                 }
3351         }
3352 
3353         /*
3354          * we don't want to touch the inode after unlocking the page,
3355          * so we update the mapping writeback index now
3356          */
3357         update_nr_written(page, wbc, nr_written + 1);
3358 
3359         end = page_end;
3360         if (i_size <= start) {
3361                 if (tree->ops && tree->ops->writepage_end_io_hook)
3362                         tree->ops->writepage_end_io_hook(page, start,
3363                                                          page_end, NULL, 1);
3364                 goto done;
3365         }
3366 
3367         blocksize = inode->i_sb->s_blocksize;
3368 
3369         while (cur <= end) {
3370                 u64 em_end;
3371                 if (cur >= i_size) {
3372                         if (tree->ops && tree->ops->writepage_end_io_hook)
3373                                 tree->ops->writepage_end_io_hook(page, cur,
3374                                                          page_end, NULL, 1);
3375                         break;
3376                 }
3377                 em = epd->get_extent(inode, page, pg_offset, cur,
3378                                      end - cur + 1, 1);
3379                 if (IS_ERR_OR_NULL(em)) {
3380                         SetPageError(page);
3381                         ret = PTR_ERR_OR_ZERO(em);
3382                         break;
3383                 }
3384 
3385                 extent_offset = cur - em->start;
3386                 em_end = extent_map_end(em);
3387                 BUG_ON(em_end <= cur);
3388                 BUG_ON(end < cur);
3389                 iosize = min(em_end - cur, end - cur + 1);
3390                 iosize = ALIGN(iosize, blocksize);
3391                 sector = (em->block_start + extent_offset) >> 9;
3392                 bdev = em->bdev;
3393                 block_start = em->block_start;
3394                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
3395                 free_extent_map(em);
3396                 em = NULL;
3397 
3398                 /*
3399                  * compressed and inline extents are written through other
3400                  * paths in the FS
3401                  */
3402                 if (compressed || block_start == EXTENT_MAP_HOLE ||
3403                     block_start == EXTENT_MAP_INLINE) {
3404                         /*
3405                          * end_io notification does not happen here for
3406                          * compressed extents
3407                          */
3408                         if (!compressed && tree->ops &&
3409                             tree->ops->writepage_end_io_hook)
3410                                 tree->ops->writepage_end_io_hook(page, cur,
3411                                                          cur + iosize - 1,
3412                                                          NULL, 1);
3413                         else if (compressed) {
3414                                 /* we don't want to end_page_writeback on
3415                                  * a compressed extent.  this happens
3416                                  * elsewhere
3417                                  */
3418                                 nr++;
3419                         }
3420 
3421                         cur += iosize;
3422                         pg_offset += iosize;
3423                         continue;
3424                 }
3425 
3426                 if (tree->ops && tree->ops->writepage_io_hook) {
3427                         ret = tree->ops->writepage_io_hook(page, cur,
3428                                                 cur + iosize - 1);
3429                 } else {
3430                         ret = 0;
3431                 }
3432                 if (ret) {
3433                         SetPageError(page);
3434                 } else {
3435                         unsigned long max_nr = (i_size >> PAGE_SHIFT) + 1;
3436 
3437                         set_range_writeback(tree, cur, cur + iosize - 1);
3438                         if (!PageWriteback(page)) {
3439                                 btrfs_err(BTRFS_I(inode)->root->fs_info,
3440                                            "page %lu not writeback, cur %llu end %llu",
3441                                        page->index, cur, end);
3442                         }
3443 
3444                         ret = submit_extent_page(write_flags, tree, wbc, page,
3445                                                  sector, iosize, pg_offset,
3446                                                  bdev, &epd->bio, max_nr,
3447                                                  end_bio_extent_writepage,
3448                                                  0, 0, 0, false);
3449                         if (ret)
3450                                 SetPageError(page);
3451                 }
3452                 cur = cur + iosize;
3453                 pg_offset += iosize;
3454                 nr++;
3455         }
3456 done:
3457         *nr_ret = nr;
3458 
3459 done_unlocked:
3460 
3461         /* drop our reference on any cached states */
3462         free_extent_state(cached_state);
3463         return ret;
3464 }
3465 
3466 /*
3467  * the writepage semantics are similar to regular writepage.  extent
3468  * records are inserted to lock ranges in the tree, and as dirty areas
3469  * are found, they are marked writeback.  Then the lock bits are removed
3470  * and the end_io handler clears the writeback ranges
3471  */
3472 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
3473                               void *data)
3474 {
3475         struct inode *inode = page->mapping->host;
3476         struct extent_page_data *epd = data;
3477         u64 start = page_offset(page);
3478         u64 page_end = start + PAGE_SIZE - 1;
3479         int ret;
3480         int nr = 0;
3481         size_t pg_offset = 0;
3482         loff_t i_size = i_size_read(inode);
3483         unsigned long end_index = i_size >> PAGE_SHIFT;
3484         int write_flags;
3485         unsigned long nr_written = 0;
3486 
3487         if (wbc->sync_mode == WB_SYNC_ALL)
3488                 write_flags = WRITE_SYNC;
3489         else
3490                 write_flags = WRITE;
3491 
3492         trace___extent_writepage(page, inode, wbc);
3493 
3494         WARN_ON(!PageLocked(page));
3495 
3496         ClearPageError(page);
3497 
3498         pg_offset = i_size & (PAGE_SIZE - 1);
3499         if (page->index > end_index ||
3500            (page->index == end_index && !pg_offset)) {
3501                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
3502                 unlock_page(page);
3503                 return 0;
3504         }
3505 
3506         if (page->index == end_index) {
3507                 char *userpage;
3508 
3509                 userpage = kmap_atomic(page);
3510                 memset(userpage + pg_offset, 0,
3511                        PAGE_SIZE - pg_offset);
3512                 kunmap_atomic(userpage);
3513                 flush_dcache_page(page);
3514         }
3515 
3516         pg_offset = 0;
3517 
3518         set_page_extent_mapped(page);
3519 
3520         ret = writepage_delalloc(inode, page, wbc, epd, start, &nr_written);
3521         if (ret == 1)
3522                 goto done_unlocked;
3523         if (ret)
3524                 goto done;
3525 
3526         ret = __extent_writepage_io(inode, page, wbc, epd,
3527                                     i_size, nr_written, write_flags, &nr);
3528         if (ret == 1)
3529                 goto done_unlocked;
3530 
3531 done:
3532         if (nr == 0) {
3533                 /* make sure the mapping tag for page dirty gets cleared */
3534                 set_page_writeback(page);
3535                 end_page_writeback(page);
3536         }
3537         if (PageError(page)) {
3538                 ret = ret < 0 ? ret : -EIO;
3539                 end_extent_writepage(page, ret, start, page_end);
3540         }
3541         unlock_page(page);
3542         return ret;
3543 
3544 done_unlocked:
3545         return 0;
3546 }
3547 
3548 void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
3549 {
3550         wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
3551                        TASK_UNINTERRUPTIBLE);
3552 }
3553 
3554 static noinline_for_stack int
3555 lock_extent_buffer_for_io(struct extent_buffer *eb,
3556                           struct btrfs_fs_info *fs_info,
3557                           struct extent_page_data *epd)
3558 {
3559         unsigned long i, num_pages;
3560         int flush = 0;
3561         int ret = 0;
3562 
3563         if (!btrfs_try_tree_write_lock(eb)) {
3564                 flush = 1;
3565                 flush_write_bio(epd);
3566                 btrfs_tree_lock(eb);
3567         }
3568 
3569         if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
3570                 btrfs_tree_unlock(eb);
3571                 if (!epd->sync_io)
3572                         return 0;
3573                 if (!flush) {
3574                         flush_write_bio(epd);
3575                         flush = 1;
3576                 }
3577                 while (1) {
3578                         wait_on_extent_buffer_writeback(eb);
3579                         btrfs_tree_lock(eb);
3580                         if (!test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags))
3581                                 break;
3582                         btrfs_tree_unlock(eb);
3583                 }
3584         }
3585 
3586         /*
3587          * We need to do this to prevent races in people who check if the eb is
3588          * under IO since we can end up having no IO bits set for a short period
3589          * of time.
3590          */
3591         spin_lock(&eb->refs_lock);
3592         if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3593                 set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3594                 spin_unlock(&eb->refs_lock);
3595                 btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
3596                 __percpu_counter_add(&fs_info->dirty_metadata_bytes,
3597                                      -eb->len,
3598                                      fs_info->dirty_metadata_batch);
3599                 ret = 1;
3600         } else {
3601                 spin_unlock(&eb->refs_lock);
3602         }
3603 
3604         btrfs_tree_unlock(eb);
3605 
3606         if (!ret)
3607                 return ret;
3608 
3609         num_pages = num_extent_pages(eb->start, eb->len);
3610         for (i = 0; i < num_pages; i++) {
3611                 struct page *p = eb->pages[i];
3612 
3613                 if (!trylock_page(p)) {
3614                         if (!flush) {
3615                                 flush_write_bio(epd);
3616                                 flush = 1;
3617                         }
3618                         lock_page(p);
3619                 }
3620         }
3621 
3622         return ret;
3623 }
3624 
3625 static void end_extent_buffer_writeback(struct extent_buffer *eb)
3626 {
3627         clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3628         smp_mb__after_atomic();
3629         wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
3630 }
3631 
3632 static void set_btree_ioerr(struct page *page)
3633 {
3634         struct extent_buffer *eb = (struct extent_buffer *)page->private;
3635         struct btrfs_inode *btree_ino = BTRFS_I(eb->fs_info->btree_inode);
3636 
3637         SetPageError(page);
3638         if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
3639                 return;
3640 
3641         /*
3642          * If writeback for a btree extent that doesn't belong to a log tree
3643          * failed, increment the counter transaction->eb_write_errors.
3644          * We do this because while the transaction is running and before it's
3645          * committing (when we call filemap_fdata[write|wait]_range against
3646          * the btree inode), we might have
3647          * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
3648          * returns an error or an error happens during writeback, when we're
3649          * committing the transaction we wouldn't know about it, since the pages
3650          * can be no longer dirty nor marked anymore for writeback (if a
3651          * subsequent modification to the extent buffer didn't happen before the
3652          * transaction commit), which makes filemap_fdata[write|wait]_range not
3653          * able to find the pages tagged with SetPageError at transaction
3654          * commit time. So if this happens we must abort the transaction,
3655          * otherwise we commit a super block with btree roots that point to
3656          * btree nodes/leafs whose content on disk is invalid - either garbage
3657          * or the content of some node/leaf from a past generation that got
3658          * cowed or deleted and is no longer valid.
3659          *
3660          * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
3661          * not be enough - we need to distinguish between log tree extents vs
3662          * non-log tree extents, and the next filemap_fdatawait_range() call
3663          * will catch and clear such errors in the mapping - and that call might
3664          * be from a log sync and not from a transaction commit. Also, checking
3665          * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
3666          * not done and would not be reliable - the eb might have been released
3667          * from memory and reading it back again means that flag would not be
3668          * set (since it's a runtime flag, not persisted on disk).
3669          *
3670          * Using the flags below in the btree inode also makes us achieve the
3671          * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
3672          * writeback for all dirty pages and before filemap_fdatawait_range()
3673          * is called, the writeback for all dirty pages had already finished
3674          * with errors - because we were not using AS_EIO/AS_ENOSPC,
3675          * filemap_fdatawait_range() would return success, as it could not know
3676          * that writeback errors happened (the pages were no longer tagged for
3677          * writeback).
3678          */
3679         switch (eb->log_index) {
3680         case -1:
3681                 set_bit(BTRFS_INODE_BTREE_ERR, &btree_ino->runtime_flags);
3682                 break;
3683         case 0:
3684                 set_bit(BTRFS_INODE_BTREE_LOG1_ERR, &btree_ino->runtime_flags);
3685                 break;
3686         case 1:
3687                 set_bit(BTRFS_INODE_BTREE_LOG2_ERR, &btree_ino->runtime_flags);
3688                 break;
3689         default:
3690                 BUG(); /* unexpected, logic error */
3691         }
3692 }
3693 
3694 static void end_bio_extent_buffer_writepage(struct bio *bio)
3695 {
3696         struct bio_vec *bvec;
3697         struct extent_buffer *eb;
3698         int i, done;
3699 
3700         bio_for_each_segment_all(bvec, bio, i) {
3701                 struct page *page = bvec->bv_page;
3702 
3703                 eb = (struct extent_buffer *)page->private;
3704                 BUG_ON(!eb);
3705                 done = atomic_dec_and_test(&eb->io_pages);
3706 
3707                 if (bio->bi_error ||
3708                     test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
3709                         ClearPageUptodate(page);
3710                         set_btree_ioerr(page);
3711                 }
3712 
3713                 end_page_writeback(page);
3714 
3715                 if (!done)
3716                         continue;
3717 
3718                 end_extent_buffer_writeback(eb);
3719         }
3720 
3721         bio_put(bio);
3722 }
3723 
3724 static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
3725                         struct btrfs_fs_info *fs_info,
3726                         struct writeback_control *wbc,
3727                         struct extent_page_data *epd)
3728 {
3729         struct block_device *bdev = fs_info->fs_devices->latest_bdev;
3730         struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
3731         u64 offset = eb->start;
3732         unsigned long i, num_pages;
3733         unsigned long bio_flags = 0;
3734         int rw = (epd->sync_io ? WRITE_SYNC : WRITE) | REQ_META;
3735         int ret = 0;
3736 
3737         clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
3738         num_pages = num_extent_pages(eb->start, eb->len);
3739         atomic_set(&eb->io_pages, num_pages);
3740         if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
3741                 bio_flags = EXTENT_BIO_TREE_LOG;
3742 
3743         for (i = 0; i < num_pages; i++) {
3744                 struct page *p = eb->pages[i];
3745 
3746                 clear_page_dirty_for_io(p);
3747                 set_page_writeback(p);
3748                 ret = submit_extent_page(rw, tree, wbc, p, offset >> 9,
3749                                          PAGE_SIZE, 0, bdev, &epd->bio,
3750                                          -1, end_bio_extent_buffer_writepage,
3751                                          0, epd->bio_flags, bio_flags, false);
3752                 epd->bio_flags = bio_flags;
3753                 if (ret) {
3754                         set_btree_ioerr(p);
3755                         end_page_writeback(p);
3756                         if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
3757                                 end_extent_buffer_writeback(eb);
3758                         ret = -EIO;
3759                         break;
3760                 }
3761                 offset += PAGE_SIZE;
3762                 update_nr_written(p, wbc, 1);
3763                 unlock_page(p);
3764         }
3765 
3766         if (unlikely(ret)) {
3767                 for (; i < num_pages; i++) {
3768                         struct page *p = eb->pages[i];
3769                         clear_page_dirty_for_io(p);
3770                         unlock_page(p);
3771                 }
3772         }
3773 
3774         return ret;
3775 }
3776 
3777 int btree_write_cache_pages(struct address_space *mapping,
3778                                    struct writeback_control *wbc)
3779 {
3780         struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
3781         struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
3782         struct extent_buffer *eb, *prev_eb = NULL;
3783         struct extent_page_data epd = {
3784                 .bio = NULL,
3785                 .tree = tree,
3786                 .extent_locked = 0,
3787                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
3788                 .bio_flags = 0,
3789         };
3790         int ret = 0;
3791         int done = 0;
3792         int nr_to_write_done = 0;
3793         struct pagevec pvec;
3794         int nr_pages;
3795         pgoff_t index;
3796         pgoff_t end;            /* Inclusive */
3797         int scanned = 0;
3798         int tag;
3799 
3800         pagevec_init(&pvec, 0);
3801         if (wbc->range_cyclic) {
3802                 index = mapping->writeback_index; /* Start from prev offset */
3803                 end = -1;
3804         } else {
3805                 index = wbc->range_start >> PAGE_SHIFT;
3806                 end = wbc->range_end >> PAGE_SHIFT;
3807                 scanned = 1;
3808         }
3809         if (wbc->sync_mode == WB_SYNC_ALL)
3810                 tag = PAGECACHE_TAG_TOWRITE;
3811         else
3812                 tag = PAGECACHE_TAG_DIRTY;
3813 retry:
3814         if (wbc->sync_mode == WB_SYNC_ALL)
3815                 tag_pages_for_writeback(mapping, index, end);
3816         while (!done && !nr_to_write_done && (index <= end) &&
3817                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3818                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3819                 unsigned i;
3820 
3821                 scanned = 1;
3822                 for (i = 0; i < nr_pages; i++) {
3823                         struct page *page = pvec.pages[i];
3824 
3825                         if (!PagePrivate(page))
3826                                 continue;
3827 
3828                         if (!wbc->range_cyclic && page->index > end) {
3829                                 done = 1;
3830                                 break;
3831                         }
3832 
3833                         spin_lock(&mapping->private_lock);
3834                         if (!PagePrivate(page)) {
3835                                 spin_unlock(&mapping->private_lock);
3836                                 continue;
3837                         }
3838 
3839                         eb = (struct extent_buffer *)page->private;
3840 
3841                         /*
3842                          * Shouldn't happen and normally this would be a BUG_ON
3843                          * but no sense in crashing the users box for something
3844                          * we can survive anyway.
3845                          */
3846                         if (WARN_ON(!eb)) {
3847                                 spin_unlock(&mapping->private_lock);
3848                                 continue;
3849                         }
3850 
3851                         if (eb == prev_eb) {
3852                                 spin_unlock(&mapping->private_lock);
3853                                 continue;
3854                         }
3855 
3856                         ret = atomic_inc_not_zero(&eb->refs);
3857                         spin_unlock(&mapping->private_lock);
3858                         if (!ret)
3859                                 continue;
3860 
3861                         prev_eb = eb;
3862                         ret = lock_extent_buffer_for_io(eb, fs_info, &epd);
3863                         if (!ret) {
3864                                 free_extent_buffer(eb);
3865                                 continue;
3866                         }
3867 
3868                         ret = write_one_eb(eb, fs_info, wbc, &epd);
3869                         if (ret) {
3870                                 done = 1;
3871                                 free_extent_buffer(eb);
3872                                 break;
3873                         }
3874                         free_extent_buffer(eb);
3875 
3876                         /*
3877                          * the filesystem may choose to bump up nr_to_write.
3878                          * We have to make sure to honor the new nr_to_write
3879                          * at any time
3880                          */
3881                         nr_to_write_done = wbc->nr_to_write <= 0;
3882                 }
3883                 pagevec_release(&pvec);
3884                 cond_resched();
3885         }
3886         if (!scanned && !done) {
3887                 /*
3888                  * We hit the last page and there is more work to be done: wrap
3889                  * back to the start of the file
3890                  */
3891                 scanned = 1;
3892                 index = 0;
3893                 goto retry;
3894         }
3895         flush_write_bio(&epd);
3896         return ret;
3897 }
3898 
3899 /**
3900  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
3901  * @mapping: address space structure to write
3902  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
3903  * @writepage: function called for each page
3904  * @data: data passed to writepage function
3905  *
3906  * If a page is already under I/O, write_cache_pages() skips it, even
3907  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
3908  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
3909  * and msync() need to guarantee that all the data which was dirty at the time
3910  * the call was made get new I/O started against them.  If wbc->sync_mode is
3911  * WB_SYNC_ALL then we were called for data integrity and we must wait for
3912  * existing IO to complete.
3913  */
3914 static int extent_write_cache_pages(struct extent_io_tree *tree,
3915                              struct address_space *mapping,
3916                              struct writeback_control *wbc,
3917                              writepage_t writepage, void *data,
3918                              void (*flush_fn)(void *))
3919 {
3920         struct inode *inode = mapping->host;
3921         int ret = 0;
3922         int done = 0;
3923         int err = 0;
3924         int nr_to_write_done = 0;
3925         struct pagevec pvec;
3926         int nr_pages;
3927         pgoff_t index;
3928         pgoff_t end;            /* Inclusive */
3929         int scanned = 0;
3930         int tag;
3931 
3932         /*
3933          * We have to hold onto the inode so that ordered extents can do their
3934          * work when the IO finishes.  The alternative to this is failing to add
3935          * an ordered extent if the igrab() fails there and that is a huge pain
3936          * to deal with, so instead just hold onto the inode throughout the
3937          * writepages operation.  If it fails here we are freeing up the inode
3938          * anyway and we'd rather not waste our time writing out stuff that is
3939          * going to be truncated anyway.
3940          */
3941         if (!igrab(inode))
3942                 return 0;
3943 
3944         pagevec_init(&pvec, 0);
3945         if (wbc->range_cyclic) {
3946                 index = mapping->writeback_index; /* Start from prev offset */
3947                 end = -1;
3948         } else {
3949                 index = wbc->range_start >> PAGE_SHIFT;
3950                 end = wbc->range_end >> PAGE_SHIFT;
3951                 scanned = 1;
3952         }
3953         if (wbc->sync_mode == WB_SYNC_ALL)
3954                 tag = PAGECACHE_TAG_TOWRITE;
3955         else
3956                 tag = PAGECACHE_TAG_DIRTY;
3957 retry:
3958         if (wbc->sync_mode == WB_SYNC_ALL)
3959                 tag_pages_for_writeback(mapping, index, end);
3960         while (!done && !nr_to_write_done && (index <= end) &&
3961                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3962                         min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3963                 unsigned i;
3964 
3965                 scanned = 1;
3966                 for (i = 0; i < nr_pages; i++) {
3967                         struct page *page = pvec.pages[i];
3968 
3969                         /*
3970                          * At this point we hold neither mapping->tree_lock nor
3971                          * lock on the page itself: the page may be truncated or
3972                          * invalidated (changing page->mapping to NULL), or even
3973                          * swizzled back from swapper_space to tmpfs file
3974                          * mapping
3975                          */
3976                         if (!trylock_page(page)) {
3977                                 flush_fn(data);
3978                                 lock_page(page);
3979                         }
3980 
3981                         if (unlikely(page->mapping != mapping)) {
3982                                 unlock_page(page);
3983                                 continue;
3984                         }
3985 
3986                         if (!wbc->range_cyclic && page->index > end) {
3987                                 done = 1;
3988                                 unlock_page(page);
3989                                 continue;
3990                         }
3991 
3992                         if (wbc->sync_mode != WB_SYNC_NONE) {
3993                                 if (PageWriteback(page))
3994                                         flush_fn(data);
3995                                 wait_on_page_writeback(page);
3996                         }
3997 
3998                         if (PageWriteback(page) ||
3999                             !clear_page_dirty_for_io(page)) {
4000                                 unlock_page(page);
4001                                 continue;
4002                         }
4003 
4004                         ret = (*writepage)(page, wbc, data);
4005 
4006                         if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
4007                                 unlock_page(page);
4008                                 ret = 0;
4009                         }
4010                         if (!err && ret < 0)
4011                                 err = ret;
4012 
4013                         /*
4014                          * the filesystem may choose to bump up nr_to_write.
4015                          * We have to make sure to honor the new nr_to_write
4016                          * at any time
4017                          */
4018                         nr_to_write_done = wbc->nr_to_write <= 0;
4019                 }
4020                 pagevec_release(&pvec);
4021                 cond_resched();
4022         }
4023         if (!scanned && !done && !err) {
4024                 /*
4025                  * We hit the last page and there is more work to be done: wrap
4026                  * back to the start of the file
4027                  */
4028                 scanned = 1;
4029                 index = 0;
4030                 goto retry;
4031         }
4032         btrfs_add_delayed_iput(inode);
4033         return err;
4034 }
4035 
4036 static void flush_epd_write_bio(struct extent_page_data *epd)
4037 {
4038         if (epd->bio) {
4039                 int rw = WRITE;
4040                 int ret;
4041 
4042                 if (epd->sync_io)
4043                         rw = WRITE_SYNC;
4044 
4045                 ret = submit_one_bio(rw, epd->bio, 0, epd->bio_flags);
4046                 BUG_ON(ret < 0); /* -ENOMEM */
4047                 epd->bio = NULL;
4048         }
4049 }
4050 
4051 static noinline void flush_write_bio(void *data)
4052 {
4053         struct extent_page_data *epd = data;
4054         flush_epd_write_bio(epd);
4055 }
4056 
4057 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
4058                           get_extent_t *get_extent,
4059                           struct writeback_control *wbc)
4060 {
4061         int ret;
4062         struct extent_page_data epd = {
4063                 .bio = NULL,
4064                 .tree = tree,
4065                 .get_extent = get_extent,
4066                 .extent_locked = 0,
4067                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4068                 .bio_flags = 0,
4069         };
4070 
4071         ret = __extent_writepage(page, wbc, &epd);
4072 
4073         flush_epd_write_bio(&epd);
4074         return ret;
4075 }
4076 
4077 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
4078                               u64 start, u64 end, get_extent_t *get_extent,
4079                               int mode)
4080 {
4081         int ret = 0;
4082         struct address_space *mapping = inode->i_mapping;
4083         struct page *page;
4084         unsigned long nr_pages = (end - start + PAGE_SIZE) >>
4085                 PAGE_SHIFT;
4086 
4087         struct extent_page_data epd = {
4088                 .bio = NULL,
4089                 .tree = tree,
4090                 .get_extent = get_extent,
4091                 .extent_locked = 1,
4092                 .sync_io = mode == WB_SYNC_ALL,
4093                 .bio_flags = 0,
4094         };
4095         struct writeback_control wbc_writepages = {
4096                 .sync_mode      = mode,
4097                 .nr_to_write    = nr_pages * 2,
4098                 .range_start    = start,
4099                 .range_end      = end + 1,
4100         };
4101 
4102         while (start <= end) {
4103                 page = find_get_page(mapping, start >> PAGE_SHIFT);
4104                 if (clear_page_dirty_for_io(page))
4105                         ret = __extent_writepage(page, &wbc_writepages, &epd);
4106                 else {
4107                         if (tree->ops && tree->ops->writepage_end_io_hook)
4108                                 tree->ops->writepage_end_io_hook(page, start,
4109                                                  start + PAGE_SIZE - 1,
4110                                                  NULL, 1);
4111                         unlock_page(page);
4112                 }
4113                 put_page(page);
4114                 start += PAGE_SIZE;
4115         }
4116 
4117         flush_epd_write_bio(&epd);
4118         return ret;
4119 }
4120 
4121 int extent_writepages(struct extent_io_tree *tree,
4122                       struct address_space *mapping,
4123                       get_extent_t *get_extent,
4124                       struct writeback_control *wbc)
4125 {
4126         int ret = 0;
4127         struct extent_page_data epd = {
4128                 .bio = NULL,
4129                 .tree = tree,
4130                 .get_extent = get_extent,
4131                 .extent_locked = 0,
4132                 .sync_io = wbc->sync_mode == WB_SYNC_ALL,
4133                 .bio_flags = 0,
4134         };
4135 
4136         ret = extent_write_cache_pages(tree, mapping, wbc,
4137                                        __extent_writepage, &epd,
4138                                        flush_write_bio);
4139         flush_epd_write_bio(&epd);
4140         return ret;
4141 }
4142 
4143 int extent_readpages(struct extent_io_tree *tree,
4144                      struct address_space *mapping,
4145                      struct list_head *pages, unsigned nr_pages,
4146                      get_extent_t get_extent)
4147 {
4148         struct bio *bio = NULL;
4149         unsigned page_idx;
4150         unsigned long bio_flags = 0;
4151         struct page *pagepool[16];
4152         struct page *page;
4153         struct extent_map *em_cached = NULL;
4154         int nr = 0;
4155         u64 prev_em_start = (u64)-1;
4156 
4157         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
4158                 page = list_entry(pages->prev, struct page, lru);
4159 
4160                 prefetchw(&page->flags);
4161                 list_del(&page->lru);
4162                 if (add_to_page_cache_lru(page, mapping,
4163                                         page->index, GFP_NOFS)) {
4164                         put_page(page);
4165                         continue;
4166                 }
4167 
4168                 pagepool[nr++] = page;
4169                 if (nr < ARRAY_SIZE(pagepool))
4170                         continue;
4171                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4172                                    &bio, 0, &bio_flags, READ, &prev_em_start);
4173                 nr = 0;
4174         }
4175         if (nr)
4176                 __extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4177                                    &bio, 0, &bio_flags, READ, &prev_em_start);
4178 
4179         if (em_cached)
4180                 free_extent_map(em_cached);
4181 
4182         BUG_ON(!list_empty(pages));
4183         if (bio)
4184                 return submit_one_bio(READ, bio, 0, bio_flags);
4185         return 0;
4186 }
4187 
4188 /*
4189  * basic invalidatepage code, this waits on any locked or writeback
4190  * ranges corresponding to the page, and then deletes any extent state
4191  * records from the tree
4192  */
4193 int extent_invalidatepage(struct extent_io_tree *tree,
4194                           struct page *page, unsigned long offset)
4195 {
4196         struct extent_state *cached_state = NULL;
4197         u64 start = page_offset(page);
4198         u64 end = start + PAGE_SIZE - 1;
4199         size_t blocksize = page->mapping->host->i_sb->s_blocksize;
4200 
4201         start += ALIGN(offset, blocksize);
4202         if (start > end)
4203                 return 0;
4204 
4205         lock_extent_bits(tree, start, end, &cached_state);
4206         wait_on_page_writeback(page);
4207         clear_extent_bit(tree, start, end,
4208                          EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
4209                          EXTENT_DO_ACCOUNTING,
4210                          1, 1, &cached_state, GFP_NOFS);
4211         return 0;
4212 }
4213 
4214 /*
4215  * a helper for releasepage, this tests for areas of the page that
4216  * are locked or under IO and drops the related state bits if it is safe
4217  * to drop the page.
4218  */
4219 static int try_release_extent_state(struct extent_map_tree *map,
4220                                     struct extent_io_tree *tree,
4221                                     struct page *page, gfp_t mask)
4222 {
4223         u64 start = page_offset(page);
4224         u64 end = start + PAGE_SIZE - 1;
4225         int ret = 1;
4226 
4227         if (test_range_bit(tree, start, end,
4228                            EXTENT_IOBITS, 0, NULL))
4229                 ret = 0;
4230         else {
4231                 if ((mask & GFP_NOFS) == GFP_NOFS)
4232                         mask = GFP_NOFS;
4233                 /*
4234                  * at this point we can safely clear everything except the
4235                  * locked bit and the nodatasum bit
4236                  */
4237                 ret = clear_extent_bit(tree, start, end,
4238                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
4239                                  0, 0, NULL, mask);
4240 
4241                 /* if clear_extent_bit failed for enomem reasons,
4242                  * we can't allow the release to continue.
4243                  */
4244                 if (ret < 0)
4245                         ret = 0;
4246                 else
4247                         ret = 1;
4248         }
4249         return ret;
4250 }
4251 
4252 /*
4253  * a helper for releasepage.  As long as there are no locked extents
4254  * in the range corresponding to the page, both state records and extent
4255  * map records are removed
4256  */
4257 int try_release_extent_mapping(struct extent_map_tree *map,
4258                                struct extent_io_tree *tree, struct page *page,
4259                                gfp_t mask)
4260 {
4261         struct extent_map *em;
4262         u64 start = page_offset(page);
4263         u64 end = start + PAGE_SIZE - 1;
4264 
4265         if (gfpflags_allow_blocking(mask) &&
4266             page->mapping->host->i_size > SZ_16M) {
4267                 u64 len;
4268                 while (start <= end) {
4269                         len = end - start + 1;
4270                         write_lock(&map->lock);
4271                         em = lookup_extent_mapping(map, start, len);
4272                         if (!em) {
4273                                 write_unlock(&map->lock);
4274                                 break;
4275                         }
4276                         if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
4277                             em->start != start) {
4278                                 write_unlock(&map->lock);
4279                                 free_extent_map(em);
4280                                 break;
4281                         }
4282                         if (!test_range_bit(tree, em->start,
4283                                             extent_map_end(em) - 1,
4284                                             EXTENT_LOCKED | EXTENT_WRITEBACK,
4285                                             0, NULL)) {
4286                                 remove_extent_mapping(map, em);
4287                                 /* once for the rb tree */
4288                                 free_extent_map(em);
4289                         }
4290                         start = extent_map_end(em);
4291                         write_unlock(&map->lock);
4292 
4293                         /* once for us */
4294                         free_extent_map(em);
4295                 }
4296         }
4297         return try_release_extent_state(map, tree, page, mask);
4298 }
4299 
4300 /*
4301  * helper function for fiemap, which doesn't want to see any holes.
4302  * This maps until we find something past 'last'
4303  */
4304 static struct extent_map *get_extent_skip_holes(struct inode *inode,
4305                                                 u64 offset,
4306                                                 u64 last,
4307                                                 get_extent_t *get_extent)
4308 {
4309         u64 sectorsize = BTRFS_I(inode)->root->sectorsize;
4310         struct extent_map *em;
4311         u64 len;
4312 
4313         if (offset >= last)
4314                 return NULL;
4315 
4316         while (1) {
4317                 len = last - offset;
4318                 if (len == 0)
4319                         break;
4320                 len = ALIGN(len, sectorsize);
4321                 em = get_extent(inode, NULL, 0, offset, len, 0);
4322                 if (IS_ERR_OR_NULL(em))
4323                         return em;
4324 
4325                 /* if this isn't a hole return it */
4326                 if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
4327                     em->block_start != EXTENT_MAP_HOLE) {
4328                         return em;
4329                 }
4330 
4331                 /* this is a hole, advance to the next extent */
4332                 offset = extent_map_end(em);
4333                 free_extent_map(em);
4334                 if (offset >= last)
4335                         break;
4336         }
4337         return NULL;
4338 }
4339 
4340 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
4341                 __u64 start, __u64 len, get_extent_t *get_extent)
4342 {
4343         int ret = 0;
4344         u64 off = start;
4345         u64 max = start + len;
4346         u32 flags = 0;
4347         u32 found_type;
4348         u64 last;
4349         u64 last_for_get_extent = 0;
4350         u64 disko = 0;
4351         u64 isize = i_size_read(inode);
4352         struct btrfs_key found_key;
4353         struct extent_map *em = NULL;
4354         struct extent_state *cached_state = NULL;
4355         struct btrfs_path *path;
4356         struct btrfs_root *root = BTRFS_I(inode)->root;
4357         int end = 0;
4358         u64 em_start = 0;
4359         u64 em_len = 0;
4360         u64 em_end = 0;
4361 
4362         if (len == 0)
4363                 return -EINVAL;
4364 
4365         path = btrfs_alloc_path();
4366         if (!path)
4367                 return -ENOMEM;
4368         path->leave_spinning = 1;
4369 
4370         start = round_down(start, BTRFS_I(inode)->root->sectorsize);
4371         len = round_up(max, BTRFS_I(inode)->root->sectorsize) - start;
4372 
4373         /*
4374          * lookup the last file extent.  We're not using i_size here
4375          * because there might be preallocation past i_size
4376          */
4377         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode), -1,
4378                                        0);
4379         if (ret < 0) {
4380                 btrfs_free_path(path);
4381                 return ret;
4382         }
4383         WARN_ON(!ret);
4384         path->slots[0]--;
4385         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
4386         found_type = found_key.type;
4387 
4388         /* No extents, but there might be delalloc bits */
4389         if (found_key.objectid != btrfs_ino(inode) ||
4390             found_type != BTRFS_EXTENT_DATA_KEY) {
4391                 /* have to trust i_size as the end */
4392                 last = (u64)-1;
4393                 last_for_get_extent = isize;
4394         } else {
4395                 /*
4396                  * remember the start of the last extent.  There are a
4397                  * bunch of different factors that go into the length of the
4398                  * extent, so its much less complex to remember where it started
4399                  */
4400                 last = found_key.offset;
4401                 last_for_get_extent = last + 1;
4402         }
4403         btrfs_release_path(path);
4404 
4405         /*
4406          * we might have some extents allocated but more delalloc past those
4407          * extents.  so, we trust isize unless the start of the last extent is
4408          * beyond isize
4409          */
4410         if (last < isize) {
4411                 last = (u64)-1;
4412                 last_for_get_extent = isize;
4413         }
4414 
4415         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4416                          &cached_state);
4417 
4418         em = get_extent_skip_holes(inode, start, last_for_get_extent,
4419                                    get_extent);
4420         if (!em)
4421                 goto out;
4422         if (IS_ERR(em)) {
4423                 ret = PTR_ERR(em);
4424                 goto out;
4425         }
4426 
4427         while (!end) {
4428                 u64 offset_in_extent = 0;
4429 
4430                 /* break if the extent we found is outside the range */
4431                 if (em->start >= max || extent_map_end(em) < off)
4432                         break;
4433 
4434                 /*
4435                  * get_extent may return an extent that starts before our
4436                  * requested range.  We have to make sure the ranges
4437                  * we return to fiemap always move forward and don't
4438                  * overlap, so adjust the offsets here
4439                  */
4440                 em_start = max(em->start, off);
4441 
4442                 /*
4443                  * record the offset from the start of the extent
4444                  * for adjusting the disk offset below.  Only do this if the
4445                  * extent isn't compressed since our in ram offset may be past
4446                  * what we have actually allocated on disk.
4447                  */
4448                 if (!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4449                         offset_in_extent = em_start - em->start;
4450                 em_end = extent_map_end(em);
4451                 em_len = em_end - em_start;
4452                 disko = 0;
4453                 flags = 0;
4454 
4455                 /*
4456                  * bump off for our next call to get_extent
4457                  */
4458                 off = extent_map_end(em);
4459                 if (off >= max)
4460                         end = 1;
4461 
4462                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
4463                         end = 1;
4464                         flags |= FIEMAP_EXTENT_LAST;
4465                 } else if (em->block_start == EXTENT_MAP_INLINE) {
4466                         flags |= (FIEMAP_EXTENT_DATA_INLINE |
4467                                   FIEMAP_EXTENT_NOT_ALIGNED);
4468                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
4469                         flags |= (FIEMAP_EXTENT_DELALLOC |
4470                                   FIEMAP_EXTENT_UNKNOWN);
4471                 } else if (fieinfo->fi_extents_max) {
4472                         u64 bytenr = em->block_start -
4473                                 (em->start - em->orig_start);
4474 
4475                         disko = em->block_start + offset_in_extent;
4476 
4477                         /*
4478                          * As btrfs supports shared space, this information
4479                          * can be exported to userspace tools via
4480                          * flag FIEMAP_EXTENT_SHARED.  If fi_extents_max == 0
4481                          * then we're just getting a count and we can skip the
4482                          * lookup stuff.
4483                          */
4484                         ret = btrfs_check_shared(NULL, root->fs_info,
4485                                                  root->objectid,
4486                                                  btrfs_ino(inode), bytenr);
4487                         if (ret < 0)
4488                                 goto out_free;
4489                         if (ret)
4490                                 flags |= FIEMAP_EXTENT_SHARED;
4491                         ret = 0;
4492                 }
4493                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4494                         flags |= FIEMAP_EXTENT_ENCODED;
4495                 if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
4496                         flags |= FIEMAP_EXTENT_UNWRITTEN;
4497 
4498                 free_extent_map(em);
4499                 em = NULL;
4500                 if ((em_start >= last) || em_len == (u64)-1 ||
4501                    (last == (u64)-1 && isize <= em_end)) {
4502                         flags |= FIEMAP_EXTENT_LAST;
4503                         end = 1;
4504                 }
4505 
4506                 /* now scan forward to see if this is really the last extent. */
4507                 em = get_extent_skip_holes(inode, off, last_for_get_extent,
4508                                            get_extent);
4509                 if (IS_ERR(em)) {
4510                         ret = PTR_ERR(em);
4511                         goto out;
4512                 }
4513                 if (!em) {
4514                         flags |= FIEMAP_EXTENT_LAST;
4515                         end = 1;
4516                 }
4517                 ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
4518                                               em_len, flags);
4519                 if (ret) {
4520                         if (ret == 1)
4521                                 ret = 0;
4522                         goto out_free;
4523                 }
4524         }
4525 out_free:
4526         free_extent_map(em);
4527 out:
4528         btrfs_free_path(path);
4529         unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4530                              &cached_state, GFP_NOFS);
4531         return ret;
4532 }
4533 
4534 static void __free_extent_buffer(struct extent_buffer *eb)
4535 {
4536         btrfs_leak_debug_del(&eb->leak_list);
4537         kmem_cache_free(extent_buffer_cache, eb);
4538 }
4539 
4540 int extent_buffer_under_io(struct extent_buffer *eb)
4541 {
4542         return (atomic_read(&eb->io_pages) ||
4543                 test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
4544                 test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4545 }
4546 
4547 /*
4548  * Helper for releasing extent buffer page.
4549  */
4550 static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
4551 {
4552         unsigned long index;
4553         struct page *page;
4554         int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4555 
4556         BUG_ON(extent_buffer_under_io(eb));
4557 
4558         index = num_extent_pages(eb->start, eb->len);
4559         if (index == 0)
4560                 return;
4561 
4562         do {
4563                 index--;
4564                 page = eb->pages[index];
4565                 if (!page)
4566                         continue;
4567                 if (mapped)
4568                         spin_lock(&page->mapping->private_lock);
4569                 /*
4570                  * We do this since we'll remove the pages after we've
4571                  * removed the eb from the radix tree, so we could race
4572                  * and have this page now attached to the new eb.  So
4573                  * only clear page_private if it's still connected to
4574                  * this eb.
4575                  */
4576                 if (PagePrivate(page) &&
4577                     page->private == (unsigned long)eb) {
4578                         BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4579                         BUG_ON(PageDirty(page));
4580                         BUG_ON(PageWriteback(page));
4581                         /*
4582                          * We need to make sure we haven't be attached
4583                          * to a new eb.
4584                          */
4585                         ClearPagePrivate(page);
4586                         set_page_private(page, 0);
4587                         /* One for the page private */
4588                         put_page(page);
4589                 }
4590 
4591                 if (mapped)
4592                         spin_unlock(&page->mapping->private_lock);
4593 
4594                 /* One for when we alloced the page */
4595                 put_page(page);
4596         } while (index != 0);
4597 }
4598 
4599 /*
4600  * Helper for releasing the extent buffer.
4601  */
4602 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
4603 {
4604         btrfs_release_extent_buffer_page(eb);
4605         __free_extent_buffer(eb);
4606 }
4607 
4608 static struct extent_buffer *
4609 __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
4610                       unsigned long len)
4611 {
4612         struct extent_buffer *eb = NULL;
4613 
4614         eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
4615         eb->start = start;
4616         eb->len = len;
4617         eb->fs_info = fs_info;
4618         eb->bflags = 0;
4619         rwlock_init(&eb->lock);
4620         atomic_set(&eb->write_locks, 0);
4621         atomic_set(&eb->read_locks, 0);
4622         atomic_set(&eb->blocking_readers, 0);
4623         atomic_set(&eb->blocking_writers, 0);
4624         atomic_set(&eb->spinning_readers, 0);
4625         atomic_set(&eb->spinning_writers, 0);
4626         eb->lock_nested = 0;
4627         init_waitqueue_head(&eb->write_lock_wq);
4628         init_waitqueue_head(&eb->read_lock_wq);
4629 
4630         btrfs_leak_debug_add(&eb->leak_list, &buffers);
4631 
4632         spin_lock_init(&eb->refs_lock);
4633         atomic_set(&eb->refs, 1);
4634         atomic_set(&eb->io_pages, 0);
4635 
4636         /*
4637          * Sanity checks, currently the maximum is 64k covered by 16x 4k pages
4638          */
4639         BUILD_BUG_ON(BTRFS_MAX_METADATA_BLOCKSIZE
4640                 > MAX_INLINE_EXTENT_BUFFER_SIZE);
4641         BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
4642 
4643         return eb;
4644 }
4645 
4646 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
4647 {
4648         unsigned long i;
4649         struct page *p;
4650         struct extent_buffer *new;
4651         unsigned long num_pages = num_extent_pages(src->start, src->len);
4652 
4653         new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
4654         if (new == NULL)
4655                 return NULL;
4656 
4657         for (i = 0; i < num_pages; i++) {
4658                 p = alloc_page(GFP_NOFS);
4659                 if (!p) {
4660                         btrfs_release_extent_buffer(new);
4661                         return NULL;
4662                 }
4663                 attach_extent_buffer_page(new, p);
4664                 WARN_ON(PageDirty(p));
4665                 SetPageUptodate(p);
4666                 new->pages[i] = p;
4667         }
4668 
4669         copy_extent_buffer(new, src, 0, 0, src->len);
4670         set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
4671         set_bit(EXTENT_BUFFER_DUMMY, &new->bflags);
4672 
4673         return new;
4674 }
4675 
4676 struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4677                                                   u64 start, unsigned long len)
4678 {
4679         struct extent_buffer *eb;
4680         unsigned long num_pages;
4681         unsigned long i;
4682 
4683         num_pages = num_extent_pages(start, len);
4684 
4685         eb = __alloc_extent_buffer(fs_info, start, len);
4686         if (!eb)
4687                 return NULL;
4688 
4689         for (i = 0; i < num_pages; i++) {
4690                 eb->pages[i] = alloc_page(GFP_NOFS);
4691                 if (!eb->pages[i])
4692                         goto err;
4693         }
4694         set_extent_buffer_uptodate(eb);
4695         btrfs_set_header_nritems(eb, 0);
4696         set_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4697 
4698         return eb;
4699 err:
4700         for (; i > 0; i--)
4701                 __free_page(eb->pages[i - 1]);
4702         __free_extent_buffer(eb);
4703         return NULL;
4704 }
4705 
4706 struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4707                                                 u64 start)
4708 {
4709         unsigned long len;
4710 
4711         if (!fs_info) {
4712                 /*
4713                  * Called only from tests that don't always have a fs_info
4714                  * available, but we know that nodesize is 4096
4715                  */
4716                 len = 4096;
4717         } else {
4718                 len = fs_info->tree_root->nodesize;
4719         }
4720 
4721         return __alloc_dummy_extent_buffer(fs_info, start, len);
4722 }
4723 
4724 static void check_buffer_tree_ref(struct extent_buffer *eb)
4725 {
4726         int refs;
4727         /* the ref bit is tricky.  We have to make sure it is set
4728          * if we have the buffer dirty.   Otherwise the
4729          * code to free a buffer can end up dropping a dirty
4730          * page
4731          *
4732          * Once the ref bit is set, it won't go away while the
4733          * buffer is dirty or in writeback, and it also won't
4734          * go away while we have the reference count on the
4735          * eb bumped.
4736          *
4737          * We can't just set the ref bit without bumping the
4738          * ref on the eb because free_extent_buffer might
4739          * see the ref bit and try to clear it.  If this happens
4740          * free_extent_buffer might end up dropping our original
4741          * ref by mistake and freeing the page before we are able
4742          * to add one more ref.
4743          *
4744          * So bump the ref count first, then set the bit.  If someone
4745          * beat us to it, drop the ref we added.
4746          */
4747         refs = atomic_read(&eb->refs);
4748         if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4749                 return;
4750 
4751         spin_lock(&eb->refs_lock);
4752         if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4753                 atomic_inc(&eb->refs);
4754         spin_unlock(&eb->refs_lock);
4755 }
4756 
4757 static void mark_extent_buffer_accessed(struct extent_buffer *eb,
4758                 struct page *accessed)
4759 {
4760         unsigned long num_pages, i;
4761 
4762         check_buffer_tree_ref(eb);
4763 
4764         num_pages = num_extent_pages(eb->start, eb->len);
4765         for (i = 0; i < num_pages; i++) {
4766                 struct page *p = eb->pages[i];
4767 
4768                 if (p != accessed)
4769                         mark_page_accessed(p);
4770         }
4771 }
4772 
4773 struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
4774                                          u64 start)
4775 {
4776         struct extent_buffer *eb;
4777 
4778         rcu_read_lock();
4779         eb = radix_tree_lookup(&fs_info->buffer_radix,
4780                                start >> PAGE_SHIFT);
4781         if (eb && atomic_inc_not_zero(&eb->refs)) {
4782                 rcu_read_unlock();
4783                 /*
4784                  * Lock our eb's refs_lock to avoid races with
4785                  * free_extent_buffer. When we get our eb it might be flagged
4786                  * with EXTENT_BUFFER_STALE and another task running
4787                  * free_extent_buffer might have seen that flag set,
4788                  * eb->refs == 2, that the buffer isn't under IO (dirty and
4789                  * writeback flags not set) and it's still in the tree (flag
4790                  * EXTENT_BUFFER_TREE_REF set), therefore being in the process
4791                  * of decrementing the extent buffer's reference count twice.
4792                  * So here we could race and increment the eb's reference count,
4793                  * clear its stale flag, mark it as dirty and drop our reference
4794                  * before the other task finishes executing free_extent_buffer,
4795                  * which would later result in an attempt to free an extent
4796                  * buffer that is dirty.
4797                  */
4798                 if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
4799                         spin_lock(&eb->refs_lock);
4800                         spin_unlock(&eb->refs_lock);
4801                 }
4802                 mark_extent_buffer_accessed(eb, NULL);
4803                 return eb;
4804         }
4805         rcu_read_unlock();
4806 
4807         return NULL;
4808 }
4809 
4810 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
4811 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
4812                                                u64 start)
4813 {
4814         struct extent_buffer *eb, *exists = NULL;
4815         int ret;
4816 
4817         eb = find_extent_buffer(fs_info, start);
4818         if (eb)
4819                 return eb;
4820         eb = alloc_dummy_extent_buffer(fs_info, start);
4821         if (!eb)
4822                 return NULL;
4823         eb->fs_info = fs_info;
4824 again:
4825         ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
4826         if (ret)
4827                 goto free_eb;
4828         spin_lock(&fs_info->buffer_lock);
4829         ret = radix_tree_insert(&fs_info->buffer_radix,
4830                                 start >> PAGE_SHIFT, eb);
4831         spin_unlock(&fs_info->buffer_lock);
4832         radix_tree_preload_end();
4833         if (ret == -EEXIST) {
4834                 exists = find_extent_buffer(fs_info, start);
4835                 if (exists)
4836                         goto free_eb;
4837                 else
4838                         goto again;
4839         }
4840         check_buffer_tree_ref(eb);
4841         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4842 
4843         /*
4844          * We will free dummy extent buffer's if they come into
4845          * free_extent_buffer with a ref count of 2, but if we are using this we
4846          * want the buffers to stay in memory until we're done with them, so
4847          * bump the ref count again.
4848          */
4849         atomic_inc(&eb->refs);
4850         return eb;
4851 free_eb:
4852         btrfs_release_extent_buffer(eb);
4853         return exists;
4854 }
4855 #endif
4856 
4857 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
4858                                           u64 start)
4859 {
4860         unsigned long len = fs_info->tree_root->nodesize;
4861         unsigned long num_pages = num_extent_pages(start, len);
4862         unsigned long i;
4863         unsigned long index = start >> PAGE_SHIFT;
4864         struct extent_buffer *eb;
4865         struct extent_buffer *exists = NULL;
4866         struct page *p;
4867         struct address_space *mapping = fs_info->btree_inode->i_mapping;
4868         int uptodate = 1;
4869         int ret;
4870 
4871         eb = find_extent_buffer(fs_info, start);
4872         if (eb)
4873                 return eb;
4874 
4875         eb = __alloc_extent_buffer(fs_info, start, len);
4876         if (!eb)
4877                 return NULL;
4878 
4879         for (i = 0; i < num_pages; i++, index++) {
4880                 p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL);
4881                 if (!p)
4882                         goto free_eb;
4883 
4884                 spin_lock(&mapping->private_lock);
4885                 if (PagePrivate(p)) {
4886                         /*
4887                          * We could have already allocated an eb for this page
4888                          * and attached one so lets see if we can get a ref on
4889                          * the existing eb, and if we can we know it's good and
4890                          * we can just return that one, else we know we can just
4891                          * overwrite page->private.
4892                          */
4893                         exists = (struct extent_buffer *)p->private;
4894                         if (atomic_inc_not_zero(&exists->refs)) {
4895                                 spin_unlock(&mapping->private_lock);
4896                                 unlock_page(p);
4897                                 put_page(p);
4898                                 mark_extent_buffer_accessed(exists, p);
4899                                 goto free_eb;
4900                         }
4901                         exists = NULL;
4902 
4903                         /*
4904                          * Do this so attach doesn't complain and we need to
4905                          * drop the ref the old guy had.
4906                          */
4907                         ClearPagePrivate(p);
4908                         WARN_ON(PageDirty(p));
4909                         put_page(p);
4910                 }
4911                 attach_extent_buffer_page(eb, p);
4912                 spin_unlock(&mapping->private_lock);
4913                 WARN_ON(PageDirty(p));
4914                 eb->pages[i] = p;
4915                 if (!PageUptodate(p))
4916                         uptodate = 0;
4917 
4918                 /*
4919                  * see below about how we avoid a nasty race with release page
4920                  * and why we unlock later
4921                  */
4922         }
4923         if (uptodate)
4924                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
4925 again:
4926         ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
4927         if (ret)
4928                 goto free_eb;
4929 
4930         spin_lock(&fs_info->buffer_lock);
4931         ret = radix_tree_insert(&fs_info->buffer_radix,
4932                                 start >> PAGE_SHIFT, eb);
4933         spin_unlock(&fs_info->buffer_lock);
4934         radix_tree_preload_end();
4935         if (ret == -EEXIST) {
4936                 exists = find_extent_buffer(fs_info, start);
4937                 if (exists)
4938                         goto free_eb;
4939                 else
4940                         goto again;
4941         }
4942         /* add one reference for the tree */
4943         check_buffer_tree_ref(eb);
4944         set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4945 
4946         /*
4947          * there is a race where release page may have
4948          * tried to find this extent buffer in the radix
4949          * but failed.  It will tell the VM it is safe to
4950          * reclaim the, and it will clear the page private bit.
4951          * We must make sure to set the page private bit properly
4952          * after the extent buffer is in the radix tree so
4953          * it doesn't get lost
4954          */
4955         SetPageChecked(eb->pages[0]);
4956         for (i = 1; i < num_pages; i++) {
4957                 p = eb->pages[i];
4958                 ClearPageChecked(p);
4959                 unlock_page(p);
4960         }
4961         unlock_page(eb->pages[0]);
4962         return eb;
4963 
4964 free_eb:
4965         WARN_ON(!atomic_dec_and_test(&eb->refs));
4966         for (i = 0; i < num_pages; i++) {
4967                 if (eb->pages[i])
4968                         unlock_page(eb->pages[i]);
4969         }
4970 
4971         btrfs_release_extent_buffer(eb);
4972         return exists;
4973 }
4974 
4975 static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
4976 {
4977         struct extent_buffer *eb =
4978                         container_of(head, struct extent_buffer, rcu_head);
4979 
4980         __free_extent_buffer(eb);
4981 }
4982 
4983 /* Expects to have eb->eb_lock already held */
4984 static int release_extent_buffer(struct extent_buffer *eb)
4985 {
4986         WARN_ON(atomic_read(&eb->refs) == 0);
4987         if (atomic_dec_and_test(&eb->refs)) {
4988                 if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) {
4989                         struct btrfs_fs_info *fs_info = eb->fs_info;
4990 
4991                         spin_unlock(&eb->refs_lock);
4992 
4993                         spin_lock(&fs_info->buffer_lock);
4994                         radix_tree_delete(&fs_info->buffer_radix,
4995                                           eb->start >> PAGE_SHIFT);
4996                         spin_unlock(&fs_info->buffer_lock);
4997                 } else {
4998                         spin_unlock(&eb->refs_lock);
4999                 }
5000 
5001                 /* Should be safe to release our pages at this point */
5002                 btrfs_release_extent_buffer_page(eb);
5003 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
5004                 if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))) {
5005                         __free_extent_buffer(eb);
5006                         return 1;
5007                 }
5008 #endif
5009                 call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
5010                 return 1;
5011         }
5012         spin_unlock(&eb->refs_lock);
5013 
5014         return 0;
5015 }
5016 
5017 void free_extent_buffer(struct extent_buffer *eb)
5018 {
5019         int refs;
5020         int old;
5021         if (!eb)
5022                 return;
5023 
5024         while (1) {
5025                 refs = atomic_read(&eb->refs);
5026                 if (refs <= 3)
5027                         break;
5028                 old = atomic_cmpxchg(&eb->refs, refs, refs - 1);
5029                 if (old == refs)
5030                         return;
5031         }
5032 
5033         spin_lock(&eb->refs_lock);
5034         if (atomic_read(&eb->refs) == 2 &&
5035             test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))
5036                 atomic_dec(&eb->refs);
5037 
5038         if (atomic_read(&eb->refs) == 2 &&
5039             test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
5040             !extent_buffer_under_io(eb) &&
5041             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5042                 atomic_dec(&eb->refs);
5043 
5044         /*
5045          * I know this is terrible, but it's temporary until we stop tracking
5046          * the uptodate bits and such for the extent buffers.
5047          */
5048         release_extent_buffer(eb);
5049 }
5050 
5051 void free_extent_buffer_stale(struct extent_buffer *eb)
5052 {
5053         if (!eb)
5054                 return;
5055 
5056         spin_lock(&eb->refs_lock);
5057         set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
5058 
5059         if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
5060             test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5061                 atomic_dec(&eb->refs);
5062         release_extent_buffer(eb);
5063 }
5064 
5065 void clear_extent_buffer_dirty(struct extent_buffer *eb)
5066 {
5067         unsigned long i;
5068         unsigned long num_pages;
5069         struct page *page;
5070 
5071         num_pages = num_extent_pages(eb->start, eb->len);
5072 
5073         for (i = 0; i < num_pages; i++) {
5074                 page = eb->pages[i];
5075                 if (!PageDirty(page))
5076                         continue;
5077 
5078                 lock_page(page);
5079                 WARN_ON(!PagePrivate(page));
5080 
5081                 clear_page_dirty_for_io(page);
5082                 spin_lock_irq(&page->mapping->tree_lock);
5083                 if (!PageDirty(page)) {
5084                         radix_tree_tag_clear(&page->mapping->page_tree,
5085                                                 page_index(page),
5086                                                 PAGECACHE_TAG_DIRTY);
5087                 }
5088                 spin_unlock_irq(&page->mapping->tree_lock);
5089                 ClearPageError(page);
5090                 unlock_page(page);
5091         }
5092         WARN_ON(atomic_read(&eb->refs) == 0);
5093 }
5094 
5095 int set_extent_buffer_dirty(struct extent_buffer *eb)
5096 {
5097         unsigned long i;
5098         unsigned long num_pages;
5099         int was_dirty = 0;
5100 
5101         check_buffer_tree_ref(eb);
5102 
5103         was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
5104 
5105         num_pages = num_extent_pages(eb->start, eb->len);
5106         WARN_ON(atomic_read(&eb->refs) == 0);
5107         WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
5108 
5109         for (i = 0; i < num_pages; i++)
5110                 set_page_dirty(eb->pages[i]);
5111         return was_dirty;
5112 }
5113 
5114 void clear_extent_buffer_uptodate(struct extent_buffer *eb)
5115 {
5116         unsigned long i;
5117         struct page *page;
5118         unsigned long num_pages;
5119 
5120         clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5121         num_pages = num_extent_pages(eb->start, eb->len);
5122         for (i = 0; i < num_pages; i++) {
5123                 page = eb->pages[i];
5124                 if (page)
5125                         ClearPageUptodate(page);
5126         }
5127 }
5128 
5129 void set_extent_buffer_uptodate(struct extent_buffer *eb)
5130 {
5131         unsigned long i;
5132         struct page *page;
5133         unsigned long num_pages;
5134 
5135         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5136         num_pages = num_extent_pages(eb->start, eb->len);
5137         for (i = 0; i < num_pages; i++) {
5138                 page = eb->pages[i];
5139                 SetPageUptodate(page);
5140         }
5141 }
5142 
5143 int extent_buffer_uptodate(struct extent_buffer *eb)
5144 {
5145         return test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5146 }
5147 
5148 int read_extent_buffer_pages(struct extent_io_tree *tree,
5149                              struct extent_buffer *eb, u64 start, int wait,
5150                              get_extent_t *get_extent, int mirror_num)
5151 {
5152         unsigned long i;
5153         unsigned long start_i;
5154         struct page *page;
5155         int err;
5156         int ret = 0;
5157         int locked_pages = 0;
5158         int all_uptodate = 1;
5159         unsigned long num_pages;
5160         unsigned long num_reads = 0;
5161         struct bio *bio = NULL;
5162         unsigned long bio_flags = 0;
5163 
5164         if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
5165                 return 0;
5166 
5167         if (start) {
5168                 WARN_ON(start < eb->start);
5169                 start_i = (start >> PAGE_SHIFT) -
5170                         (eb->start >> PAGE_SHIFT);
5171         } else {
5172                 start_i = 0;
5173         }
5174 
5175         num_pages = num_extent_pages(eb->start, eb->len);
5176         for (i = start_i; i < num_pages; i++) {
5177                 page = eb->pages[i];
5178                 if (wait == WAIT_NONE) {
5179                         if (!trylock_page(page))
5180                                 goto unlock_exit;
5181                 } else {
5182                         lock_page(page);
5183                 }
5184                 locked_pages++;
5185                 if (!PageUptodate(page)) {
5186                         num_reads++;
5187                         all_uptodate = 0;
5188                 }
5189         }
5190         if (all_uptodate) {
5191                 if (start_i == 0)
5192                         set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5193                 goto unlock_exit;
5194         }
5195 
5196         clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
5197         eb->read_mirror = 0;
5198         atomic_set(&eb->io_pages, num_reads);
5199         for (i = start_i; i < num_pages; i++) {
5200                 page = eb->pages[i];
5201                 if (!PageUptodate(page)) {
5202                         ClearPageError(page);
5203                         err = __extent_read_full_page(tree, page,
5204                                                       get_extent, &bio,
5205                                                       mirror_num, &bio_flags,
5206                                                       READ | REQ_META);
5207                         if (err)
5208                                 ret = err;
5209                 } else {
5210                         unlock_page(page);
5211                 }
5212         }
5213 
5214         if (bio) {
5215                 err = submit_one_bio(READ | REQ_META, bio, mirror_num,
5216                                      bio_flags);
5217                 if (err)
5218                         return err;
5219         }
5220 
5221         if (ret || wait != WAIT_COMPLETE)
5222                 return ret;
5223 
5224         for (i = start_i; i < num_pages; i++) {
5225                 page = eb->pages[i];
5226                 wait_on_page_locked(page);
5227                 if (!PageUptodate(page))
5228                         ret = -EIO;
5229         }
5230 
5231         return ret;
5232 
5233 unlock_exit:
5234         i = start_i;
5235         while (locked_pages > 0) {
5236                 page = eb->pages[i];
5237                 i++;
5238                 unlock_page(page);
5239                 locked_pages--;
5240         }
5241         return ret;
5242 }
5243 
5244 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
5245                         unsigned long start,
5246                         unsigned long len)
5247 {
5248         size_t cur;
5249         size_t offset;
5250         struct page *page;
5251         char *kaddr;
5252         char *dst = (char *)dstv;
5253         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5254         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5255 
5256         WARN_ON(start > eb->len);
5257         WARN_ON(start + len > eb->start + eb->len);
5258 
5259         offset = (start_offset + start) & (PAGE_SIZE - 1);
5260 
5261         while (len > 0) {
5262                 page = eb->pages[i];
5263 
5264                 cur = min(len, (PAGE_SIZE - offset));
5265                 kaddr = page_address(page);
5266                 memcpy(dst, kaddr + offset, cur);
5267 
5268                 dst += cur;
5269                 len -= cur;
5270                 offset = 0;
5271                 i++;
5272         }
5273 }
5274 
5275 int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
5276                         unsigned long start,
5277                         unsigned long len)
5278 {
5279         size_t cur;
5280         size_t offset;
5281         struct page *page;
5282         char *kaddr;
5283         char __user *dst = (char __user *)dstv;
5284         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5285         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5286         int ret = 0;
5287 
5288         WARN_ON(start > eb->len);
5289         WARN_ON(start + len > eb->start + eb->len);
5290 
5291         offset = (start_offset + start) & (PAGE_SIZE - 1);
5292 
5293         while (len > 0) {
5294                 page = eb->pages[i];
5295 
5296                 cur = min(len, (PAGE_SIZE - offset));
5297                 kaddr = page_address(page);
5298                 if (copy_to_user(dst, kaddr + offset, cur)) {
5299                         ret = -EFAULT;
5300                         break;
5301                 }
5302 
5303                 dst += cur;
5304                 len -= cur;
5305                 offset = 0;
5306                 i++;
5307         }
5308 
5309         return ret;
5310 }
5311 
5312 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
5313                                unsigned long min_len, char **map,
5314                                unsigned long *map_start,
5315                                unsigned long *map_len)
5316 {
5317         size_t offset = start & (PAGE_SIZE - 1);
5318         char *kaddr;
5319         struct page *p;
5320         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5321         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5322         unsigned long end_i = (start_offset + start + min_len - 1) >>
5323                 PAGE_SHIFT;
5324 
5325         if (i != end_i)
5326                 return -EINVAL;
5327 
5328         if (i == 0) {
5329                 offset = start_offset;
5330                 *map_start = 0;
5331         } else {
5332                 offset = 0;
5333                 *map_start = ((u64)i << PAGE_SHIFT) - start_offset;
5334         }
5335 
5336         if (start + min_len > eb->len) {
5337                 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, "
5338                        "wanted %lu %lu\n",
5339                        eb->start, eb->len, start, min_len);
5340                 return -EINVAL;
5341         }
5342 
5343         p = eb->pages[i];
5344         kaddr = page_address(p);
5345         *map = kaddr + offset;
5346         *map_len = PAGE_SIZE - offset;
5347         return 0;
5348 }
5349 
5350 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
5351                           unsigned long start,
5352                           unsigned long len)
5353 {
5354         size_t cur;
5355         size_t offset;
5356         struct page *page;
5357         char *kaddr;
5358         char *ptr = (char *)ptrv;
5359         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5360         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5361         int ret = 0;
5362 
5363         WARN_ON(start > eb->len);
5364         WARN_ON(start + len > eb->start + eb->len);
5365 
5366         offset = (start_offset + start) & (PAGE_SIZE - 1);
5367 
5368         while (len > 0) {
5369                 page = eb->pages[i];
5370 
5371                 cur = min(len, (PAGE_SIZE - offset));
5372 
5373                 kaddr = page_address(page);
5374                 ret = memcmp(ptr, kaddr + offset, cur);
5375                 if (ret)
5376                         break;
5377 
5378                 ptr += cur;
5379                 len -= cur;
5380                 offset = 0;
5381                 i++;
5382         }
5383         return ret;
5384 }
5385 
5386 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
5387                          unsigned long start, unsigned long len)
5388 {
5389         size_t cur;
5390         size_t offset;
5391         struct page *page;
5392         char *kaddr;
5393         char *src = (char *)srcv;
5394         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5395         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5396 
5397         WARN_ON(start > eb->len);
5398         WARN_ON(start + len > eb->start + eb->len);
5399 
5400         offset = (start_offset + start) & (PAGE_SIZE - 1);
5401 
5402         while (len > 0) {
5403                 page = eb->pages[i];
5404                 WARN_ON(!PageUptodate(page));
5405 
5406                 cur = min(len, PAGE_SIZE - offset);
5407                 kaddr = page_address(page);
5408                 memcpy(kaddr + offset, src, cur);
5409 
5410                 src += cur;
5411                 len -= cur;
5412                 offset = 0;
5413                 i++;
5414         }
5415 }
5416 
5417 void memset_extent_buffer(struct extent_buffer *eb, char c,
5418                           unsigned long start, unsigned long len)
5419 {
5420         size_t cur;
5421         size_t offset;
5422         struct page *page;
5423         char *kaddr;
5424         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5425         unsigned long i = (start_offset + start) >> PAGE_SHIFT;
5426 
5427         WARN_ON(start > eb->len);
5428         WARN_ON(start + len > eb->start + eb->len);
5429 
5430         offset = (start_offset + start) & (PAGE_SIZE - 1);
5431 
5432         while (len > 0) {
5433                 page = eb->pages[i];
5434                 WARN_ON(!PageUptodate(page));
5435 
5436                 cur = min(len, PAGE_SIZE - offset);
5437                 kaddr = page_address(page);
5438                 memset(kaddr + offset, c, cur);
5439 
5440                 len -= cur;
5441                 offset = 0;
5442                 i++;
5443         }
5444 }
5445 
5446 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
5447                         unsigned long dst_offset, unsigned long src_offset,
5448                         unsigned long len)
5449 {
5450         u64 dst_len = dst->len;
5451         size_t cur;
5452         size_t offset;
5453         struct page *page;
5454         char *kaddr;
5455         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5456         unsigned long i = (start_offset + dst_offset) >> PAGE_SHIFT;
5457 
5458         WARN_ON(src->len != dst_len);
5459 
5460         offset = (start_offset + dst_offset) &
5461                 (PAGE_SIZE - 1);
5462 
5463         while (len > 0) {
5464                 page = dst->pages[i];
5465                 WARN_ON(!PageUptodate(page));
5466 
5467                 cur = min(len, (unsigned long)(PAGE_SIZE - offset));
5468 
5469                 kaddr = page_address(page);
5470                 read_extent_buffer(src, kaddr + offset, src_offset, cur);
5471 
5472                 src_offset += cur;
5473                 len -= cur;
5474                 offset = 0;
5475                 i++;
5476         }
5477 }
5478 
5479 /*
5480  * The extent buffer bitmap operations are done with byte granularity because
5481  * bitmap items are not guaranteed to be aligned to a word and therefore a
5482  * single word in a bitmap may straddle two pages in the extent buffer.
5483  */
5484 #define BIT_BYTE(nr) ((nr) / BITS_PER_BYTE)
5485 #define BYTE_MASK ((1 << BITS_PER_BYTE) - 1)
5486 #define BITMAP_FIRST_BYTE_MASK(start) \
5487         ((BYTE_MASK << ((start) & (BITS_PER_BYTE - 1))) & BYTE_MASK)
5488 #define BITMAP_LAST_BYTE_MASK(nbits) \
5489         (BYTE_MASK >> (-(nbits) & (BITS_PER_BYTE - 1)))
5490 
5491 /*
5492  * eb_bitmap_offset() - calculate the page and offset of the byte containing the
5493  * given bit number
5494  * @eb: the extent buffer
5495  * @start: offset of the bitmap item in the extent buffer
5496  * @nr: bit number
5497  * @page_index: return index of the page in the extent buffer that contains the
5498  * given bit number
5499  * @page_offset: return offset into the page given by page_index
5500  *
5501  * This helper hides the ugliness of finding the byte in an extent buffer which
5502  * contains a given bit.
5503  */
5504 static inline void eb_bitmap_offset(struct extent_buffer *eb,
5505                                     unsigned long start, unsigned long nr,
5506                                     unsigned long *page_index,
5507                                     size_t *page_offset)
5508 {
5509         size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1);
5510         size_t byte_offset = BIT_BYTE(nr);
5511         size_t offset;
5512 
5513         /*
5514          * The byte we want is the offset of the extent buffer + the offset of
5515          * the bitmap item in the extent buffer + the offset of the byte in the
5516          * bitmap item.
5517          */
5518         offset = start_offset + start + byte_offset;
5519 
5520         *page_index = offset >> PAGE_SHIFT;
5521         *page_offset = offset & (PAGE_SIZE - 1);
5522 }
5523 
5524 /**
5525  * extent_buffer_test_bit - determine whether a bit in a bitmap item is set
5526  * @eb: the extent buffer
5527  * @start: offset of the bitmap item in the extent buffer
5528  * @nr: bit number to test
5529  */
5530 int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
5531                            unsigned long nr)
5532 {
5533         char *kaddr;
5534         struct page *page;
5535         unsigned long i;
5536         size_t offset;
5537 
5538         eb_bitmap_offset(eb, start, nr, &i, &offset);
5539         page = eb->pages[i];
5540         WARN_ON(!PageUptodate(page));
5541         kaddr = page_address(page);
5542         return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1)));
5543 }
5544 
5545 /**
5546  * extent_buffer_bitmap_set - set an area of a bitmap
5547  * @eb: the extent buffer
5548  * @start: offset of the bitmap item in the extent buffer
5549  * @pos: bit number of the first bit
5550  * @len: number of bits to set
5551  */
5552 void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
5553                               unsigned long pos, unsigned long len)
5554 {
5555         char *kaddr;
5556         struct page *page;
5557         unsigned long i;
5558         size_t offset;
5559         const unsigned int size = pos + len;
5560         int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5561         unsigned int mask_to_set = BITMAP_FIRST_BYTE_MASK(pos);
5562 
5563         eb_bitmap_offset(eb, start, pos, &i, &offset);
5564         page = eb->pages[i];
5565         WARN_ON(!PageUptodate(page));
5566         kaddr = page_address(page);
5567 
5568         while (len >= bits_to_set) {
5569                 kaddr[offset] |= mask_to_set;
5570                 len -= bits_to_set;
5571                 bits_to_set = BITS_PER_BYTE;
5572                 mask_to_set = ~0U;
5573                 if (++offset >= PAGE_SIZE && len > 0) {
5574                         offset = 0;
5575                         page = eb->pages[++i];
5576                         WARN_ON(!PageUptodate(page));
5577                         kaddr = page_address(page);
5578                 }
5579         }
5580         if (len) {
5581                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
5582                 kaddr[offset] |= mask_to_set;
5583         }
5584 }
5585 
5586 
5587 /**
5588  * extent_buffer_bitmap_clear - clear an area of a bitmap
5589  * @eb: the extent buffer
5590  * @start: offset of the bitmap item in the extent buffer
5591  * @pos: bit number of the first bit
5592  * @len: number of bits to clear
5593  */
5594 void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
5595                                 unsigned long pos, unsigned long len)
5596 {
5597         char *kaddr;
5598         struct page *page;
5599         unsigned long i;
5600         size_t offset;
5601         const unsigned int size = pos + len;
5602         int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
5603         unsigned int mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos);
5604 
5605         eb_bitmap_offset(eb, start, pos, &i, &offset);
5606         page = eb->pages[i];
5607         WARN_ON(!PageUptodate(page));
5608         kaddr = page_address(page);
5609 
5610         while (len >= bits_to_clear) {
5611                 kaddr[offset] &= ~mask_to_clear;
5612                 len -= bits_to_clear;
5613                 bits_to_clear = BITS_PER_BYTE;
5614                 mask_to_clear = ~0U;
5615                 if (++offset >= PAGE_SIZE && len > 0) {
5616                         offset = 0;
5617                         page = eb->pages[++i];
5618                         WARN_ON(!PageUptodate(page));
5619                         kaddr = page_address(page);
5620                 }
5621         }
5622         if (len) {
5623                 mask_to_clear &= BITMAP_LAST_BYTE_MASK(size);
5624                 kaddr[offset] &= ~mask_to_clear;
5625         }
5626 }
5627 
5628 static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
5629 {
5630         unsigned long distance = (src > dst) ? src - dst : dst - src;
5631         return distance < len;
5632 }
5633 
5634 static void copy_pages(struct page *dst_page, struct page *src_page,
5635                        unsigned long dst_off, unsigned long src_off,
5636                        unsigned long len)
5637 {
5638         char *dst_kaddr = page_address(dst_page);
5639         char *src_kaddr;
5640         int must_memmove = 0;
5641 
5642         if (dst_page != src_page) {
5643                 src_kaddr = page_address(src_page);
5644         } else {
5645                 src_kaddr = dst_kaddr;
5646                 if (areas_overlap(src_off, dst_off, len))
5647                         must_memmove = 1;
5648         }
5649 
5650         if (must_memmove)
5651                 memmove(dst_kaddr + dst_off, src_kaddr + src_off, len);
5652         else
5653                 memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
5654 }
5655 
5656 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5657                            unsigned long src_offset, unsigned long len)
5658 {
5659         size_t cur;
5660         size_t dst_off_in_page;
5661         size_t src_off_in_page;
5662         size_t start_offset = dst->start & ((u64)PAGE_SIZE - 1);
5663         unsigned long dst_i;
5664         unsigned long src_i;
5665 
5666         if (src_offset + len > dst->len) {
5667                 btrfs_err(dst->fs_info,
5668                         "memmove bogus src_offset %lu move "
5669                        "len %lu dst len %lu", src_offset, len, dst->len);
5670                 BUG_ON(1);
5671         }
5672         if (dst_offset + len > dst->len) {
5673                 btrfs_err(dst->fs_info,
5674                         "memmove bogus dst_offset %lu move "
5675                        "len %lu dst len %lu", dst_offset, len, dst->len);
5676                 BUG_ON(1);
5677         }
5678 
5679         while (len > 0) {
5680                 dst_off_in_page = (start_offset + dst_offset) &
5681                         (PAGE_SIZE - 1);
5682                 src_off_in_page = (start_offset + src_offset) &
5683                         (PAGE_SIZE - 1);
5684 
5685                 dst_i = (start_offset + dst_offset) >> PAGE_SHIFT;
5686                 src_i = (start_offset + src_offset) >> PAGE_SHIFT;
5687 
5688                 cur = min(len, (unsigned long)(PAGE_SIZE -
5689                                                src_off_in_page));
5690                 cur = min_t(unsigned long, cur,