xref: /openbmc/linux/fs/btrfs/extent_io.c (revision 9b9c2cd4)
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 	if (extent_state_cache)
210 		kmem_cache_destroy(extent_state_cache);
211 	if (extent_buffer_cache)
212 		kmem_cache_destroy(extent_buffer_cache);
213 	if (btrfs_bioset)
214 		bioset_free(btrfs_bioset);
215 }
216 
217 void extent_io_tree_init(struct extent_io_tree *tree,
218 			 struct address_space *mapping)
219 {
220 	tree->state = RB_ROOT;
221 	tree->ops = NULL;
222 	tree->dirty_bytes = 0;
223 	spin_lock_init(&tree->lock);
224 	tree->mapping = mapping;
225 }
226 
227 static struct extent_state *alloc_extent_state(gfp_t mask)
228 {
229 	struct extent_state *state;
230 
231 	state = kmem_cache_alloc(extent_state_cache, mask);
232 	if (!state)
233 		return state;
234 	state->state = 0;
235 	state->private = 0;
236 	RB_CLEAR_NODE(&state->rb_node);
237 	btrfs_leak_debug_add(&state->leak_list, &states);
238 	atomic_set(&state->refs, 1);
239 	init_waitqueue_head(&state->wq);
240 	trace_alloc_extent_state(state, mask, _RET_IP_);
241 	return state;
242 }
243 
244 void free_extent_state(struct extent_state *state)
245 {
246 	if (!state)
247 		return;
248 	if (atomic_dec_and_test(&state->refs)) {
249 		WARN_ON(extent_state_in_tree(state));
250 		btrfs_leak_debug_del(&state->leak_list);
251 		trace_free_extent_state(state, _RET_IP_);
252 		kmem_cache_free(extent_state_cache, state);
253 	}
254 }
255 
256 static struct rb_node *tree_insert(struct rb_root *root,
257 				   struct rb_node *search_start,
258 				   u64 offset,
259 				   struct rb_node *node,
260 				   struct rb_node ***p_in,
261 				   struct rb_node **parent_in)
262 {
263 	struct rb_node **p;
264 	struct rb_node *parent = NULL;
265 	struct tree_entry *entry;
266 
267 	if (p_in && parent_in) {
268 		p = *p_in;
269 		parent = *parent_in;
270 		goto do_insert;
271 	}
272 
273 	p = search_start ? &search_start : &root->rb_node;
274 	while (*p) {
275 		parent = *p;
276 		entry = rb_entry(parent, struct tree_entry, rb_node);
277 
278 		if (offset < entry->start)
279 			p = &(*p)->rb_left;
280 		else if (offset > entry->end)
281 			p = &(*p)->rb_right;
282 		else
283 			return parent;
284 	}
285 
286 do_insert:
287 	rb_link_node(node, parent, p);
288 	rb_insert_color(node, root);
289 	return NULL;
290 }
291 
292 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
293 				      struct rb_node **prev_ret,
294 				      struct rb_node **next_ret,
295 				      struct rb_node ***p_ret,
296 				      struct rb_node **parent_ret)
297 {
298 	struct rb_root *root = &tree->state;
299 	struct rb_node **n = &root->rb_node;
300 	struct rb_node *prev = NULL;
301 	struct rb_node *orig_prev = NULL;
302 	struct tree_entry *entry;
303 	struct tree_entry *prev_entry = NULL;
304 
305 	while (*n) {
306 		prev = *n;
307 		entry = rb_entry(prev, struct tree_entry, rb_node);
308 		prev_entry = entry;
309 
310 		if (offset < entry->start)
311 			n = &(*n)->rb_left;
312 		else if (offset > entry->end)
313 			n = &(*n)->rb_right;
314 		else
315 			return *n;
316 	}
317 
318 	if (p_ret)
319 		*p_ret = n;
320 	if (parent_ret)
321 		*parent_ret = prev;
322 
323 	if (prev_ret) {
324 		orig_prev = prev;
325 		while (prev && offset > prev_entry->end) {
326 			prev = rb_next(prev);
327 			prev_entry = rb_entry(prev, struct tree_entry, rb_node);
328 		}
329 		*prev_ret = prev;
330 		prev = orig_prev;
331 	}
332 
333 	if (next_ret) {
334 		prev_entry = rb_entry(prev, struct tree_entry, rb_node);
335 		while (prev && offset < prev_entry->start) {
336 			prev = rb_prev(prev);
337 			prev_entry = rb_entry(prev, struct tree_entry, rb_node);
338 		}
339 		*next_ret = prev;
340 	}
341 	return NULL;
342 }
343 
344 static inline struct rb_node *
345 tree_search_for_insert(struct extent_io_tree *tree,
346 		       u64 offset,
347 		       struct rb_node ***p_ret,
348 		       struct rb_node **parent_ret)
349 {
350 	struct rb_node *prev = NULL;
351 	struct rb_node *ret;
352 
353 	ret = __etree_search(tree, offset, &prev, NULL, p_ret, parent_ret);
354 	if (!ret)
355 		return prev;
356 	return ret;
357 }
358 
359 static inline struct rb_node *tree_search(struct extent_io_tree *tree,
360 					  u64 offset)
361 {
362 	return tree_search_for_insert(tree, offset, NULL, NULL);
363 }
364 
365 static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
366 		     struct extent_state *other)
367 {
368 	if (tree->ops && tree->ops->merge_extent_hook)
369 		tree->ops->merge_extent_hook(tree->mapping->host, new,
370 					     other);
371 }
372 
373 /*
374  * utility function to look for merge candidates inside a given range.
375  * Any extents with matching state are merged together into a single
376  * extent in the tree.  Extents with EXTENT_IO in their state field
377  * are not merged because the end_io handlers need to be able to do
378  * operations on them without sleeping (or doing allocations/splits).
379  *
380  * This should be called with the tree lock held.
381  */
382 static void merge_state(struct extent_io_tree *tree,
383 		        struct extent_state *state)
384 {
385 	struct extent_state *other;
386 	struct rb_node *other_node;
387 
388 	if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
389 		return;
390 
391 	other_node = rb_prev(&state->rb_node);
392 	if (other_node) {
393 		other = rb_entry(other_node, struct extent_state, rb_node);
394 		if (other->end == state->start - 1 &&
395 		    other->state == state->state) {
396 			merge_cb(tree, state, other);
397 			state->start = other->start;
398 			rb_erase(&other->rb_node, &tree->state);
399 			RB_CLEAR_NODE(&other->rb_node);
400 			free_extent_state(other);
401 		}
402 	}
403 	other_node = rb_next(&state->rb_node);
404 	if (other_node) {
405 		other = rb_entry(other_node, struct extent_state, rb_node);
406 		if (other->start == state->end + 1 &&
407 		    other->state == state->state) {
408 			merge_cb(tree, state, other);
409 			state->end = other->end;
410 			rb_erase(&other->rb_node, &tree->state);
411 			RB_CLEAR_NODE(&other->rb_node);
412 			free_extent_state(other);
413 		}
414 	}
415 }
416 
417 static void set_state_cb(struct extent_io_tree *tree,
418 			 struct extent_state *state, unsigned *bits)
419 {
420 	if (tree->ops && tree->ops->set_bit_hook)
421 		tree->ops->set_bit_hook(tree->mapping->host, state, bits);
422 }
423 
424 static void clear_state_cb(struct extent_io_tree *tree,
425 			   struct extent_state *state, unsigned *bits)
426 {
427 	if (tree->ops && tree->ops->clear_bit_hook)
428 		tree->ops->clear_bit_hook(tree->mapping->host, state, bits);
429 }
430 
431 static void set_state_bits(struct extent_io_tree *tree,
432 			   struct extent_state *state, unsigned *bits,
433 			   struct extent_changeset *changeset);
434 
435 /*
436  * insert an extent_state struct into the tree.  'bits' are set on the
437  * struct before it is inserted.
438  *
439  * This may return -EEXIST if the extent is already there, in which case the
440  * state struct is freed.
441  *
442  * The tree lock is not taken internally.  This is a utility function and
443  * probably isn't what you want to call (see set/clear_extent_bit).
444  */
445 static int insert_state(struct extent_io_tree *tree,
446 			struct extent_state *state, u64 start, u64 end,
447 			struct rb_node ***p,
448 			struct rb_node **parent,
449 			unsigned *bits, struct extent_changeset *changeset)
450 {
451 	struct rb_node *node;
452 
453 	if (end < start)
454 		WARN(1, KERN_ERR "BTRFS: end < start %llu %llu\n",
455 		       end, start);
456 	state->start = start;
457 	state->end = end;
458 
459 	set_state_bits(tree, state, bits, changeset);
460 
461 	node = tree_insert(&tree->state, NULL, end, &state->rb_node, p, parent);
462 	if (node) {
463 		struct extent_state *found;
464 		found = rb_entry(node, struct extent_state, rb_node);
465 		printk(KERN_ERR "BTRFS: found node %llu %llu on insert of "
466 		       "%llu %llu\n",
467 		       found->start, found->end, start, end);
468 		return -EEXIST;
469 	}
470 	merge_state(tree, state);
471 	return 0;
472 }
473 
474 static void split_cb(struct extent_io_tree *tree, struct extent_state *orig,
475 		     u64 split)
476 {
477 	if (tree->ops && tree->ops->split_extent_hook)
478 		tree->ops->split_extent_hook(tree->mapping->host, orig, split);
479 }
480 
481 /*
482  * split a given extent state struct in two, inserting the preallocated
483  * struct 'prealloc' as the newly created second half.  'split' indicates an
484  * offset inside 'orig' where it should be split.
485  *
486  * Before calling,
487  * the tree has 'orig' at [orig->start, orig->end].  After calling, there
488  * are two extent state structs in the tree:
489  * prealloc: [orig->start, split - 1]
490  * orig: [ split, orig->end ]
491  *
492  * The tree locks are not taken by this function. They need to be held
493  * by the caller.
494  */
495 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
496 		       struct extent_state *prealloc, u64 split)
497 {
498 	struct rb_node *node;
499 
500 	split_cb(tree, orig, split);
501 
502 	prealloc->start = orig->start;
503 	prealloc->end = split - 1;
504 	prealloc->state = orig->state;
505 	orig->start = split;
506 
507 	node = tree_insert(&tree->state, &orig->rb_node, prealloc->end,
508 			   &prealloc->rb_node, NULL, NULL);
509 	if (node) {
510 		free_extent_state(prealloc);
511 		return -EEXIST;
512 	}
513 	return 0;
514 }
515 
516 static struct extent_state *next_state(struct extent_state *state)
517 {
518 	struct rb_node *next = rb_next(&state->rb_node);
519 	if (next)
520 		return rb_entry(next, struct extent_state, rb_node);
521 	else
522 		return NULL;
523 }
524 
525 /*
526  * utility function to clear some bits in an extent state struct.
527  * it will optionally wake up any one waiting on this state (wake == 1).
528  *
529  * If no bits are set on the state struct after clearing things, the
530  * struct is freed and removed from the tree
531  */
532 static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
533 					    struct extent_state *state,
534 					    unsigned *bits, int wake,
535 					    struct extent_changeset *changeset)
536 {
537 	struct extent_state *next;
538 	unsigned bits_to_clear = *bits & ~EXTENT_CTLBITS;
539 
540 	if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
541 		u64 range = state->end - state->start + 1;
542 		WARN_ON(range > tree->dirty_bytes);
543 		tree->dirty_bytes -= range;
544 	}
545 	clear_state_cb(tree, state, bits);
546 	add_extent_changeset(state, bits_to_clear, changeset, 0);
547 	state->state &= ~bits_to_clear;
548 	if (wake)
549 		wake_up(&state->wq);
550 	if (state->state == 0) {
551 		next = next_state(state);
552 		if (extent_state_in_tree(state)) {
553 			rb_erase(&state->rb_node, &tree->state);
554 			RB_CLEAR_NODE(&state->rb_node);
555 			free_extent_state(state);
556 		} else {
557 			WARN_ON(1);
558 		}
559 	} else {
560 		merge_state(tree, state);
561 		next = next_state(state);
562 	}
563 	return next;
564 }
565 
566 static struct extent_state *
567 alloc_extent_state_atomic(struct extent_state *prealloc)
568 {
569 	if (!prealloc)
570 		prealloc = alloc_extent_state(GFP_ATOMIC);
571 
572 	return prealloc;
573 }
574 
575 static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
576 {
577 	btrfs_panic(tree_fs_info(tree), err, "Locking error: "
578 		    "Extent tree was modified by another "
579 		    "thread while locked.");
580 }
581 
582 /*
583  * clear some bits on a range in the tree.  This may require splitting
584  * or inserting elements in the tree, so the gfp mask is used to
585  * indicate which allocations or sleeping are allowed.
586  *
587  * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
588  * the given range from the tree regardless of state (ie for truncate).
589  *
590  * the range [start, end] is inclusive.
591  *
592  * This takes the tree lock, and returns 0 on success and < 0 on error.
593  */
594 static int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
595 			      unsigned bits, int wake, int delete,
596 			      struct extent_state **cached_state,
597 			      gfp_t mask, struct extent_changeset *changeset)
598 {
599 	struct extent_state *state;
600 	struct extent_state *cached;
601 	struct extent_state *prealloc = NULL;
602 	struct rb_node *node;
603 	u64 last_end;
604 	int err;
605 	int clear = 0;
606 
607 	btrfs_debug_check_extent_io_range(tree, start, end);
608 
609 	if (bits & EXTENT_DELALLOC)
610 		bits |= EXTENT_NORESERVE;
611 
612 	if (delete)
613 		bits |= ~EXTENT_CTLBITS;
614 	bits |= EXTENT_FIRST_DELALLOC;
615 
616 	if (bits & (EXTENT_IOBITS | EXTENT_BOUNDARY))
617 		clear = 1;
618 again:
619 	if (!prealloc && gfpflags_allow_blocking(mask)) {
620 		/*
621 		 * Don't care for allocation failure here because we might end
622 		 * up not needing the pre-allocated extent state at all, which
623 		 * is the case if we only have in the tree extent states that
624 		 * cover our input range and don't cover too any other range.
625 		 * If we end up needing a new extent state we allocate it later.
626 		 */
627 		prealloc = alloc_extent_state(mask);
628 	}
629 
630 	spin_lock(&tree->lock);
631 	if (cached_state) {
632 		cached = *cached_state;
633 
634 		if (clear) {
635 			*cached_state = NULL;
636 			cached_state = NULL;
637 		}
638 
639 		if (cached && extent_state_in_tree(cached) &&
640 		    cached->start <= start && cached->end > start) {
641 			if (clear)
642 				atomic_dec(&cached->refs);
643 			state = cached;
644 			goto hit_next;
645 		}
646 		if (clear)
647 			free_extent_state(cached);
648 	}
649 	/*
650 	 * this search will find the extents that end after
651 	 * our range starts
652 	 */
653 	node = tree_search(tree, start);
654 	if (!node)
655 		goto out;
656 	state = rb_entry(node, struct extent_state, rb_node);
657 hit_next:
658 	if (state->start > end)
659 		goto out;
660 	WARN_ON(state->end < start);
661 	last_end = state->end;
662 
663 	/* the state doesn't have the wanted bits, go ahead */
664 	if (!(state->state & bits)) {
665 		state = next_state(state);
666 		goto next;
667 	}
668 
669 	/*
670 	 *     | ---- desired range ---- |
671 	 *  | state | or
672 	 *  | ------------- state -------------- |
673 	 *
674 	 * We need to split the extent we found, and may flip
675 	 * bits on second half.
676 	 *
677 	 * If the extent we found extends past our range, we
678 	 * just split and search again.  It'll get split again
679 	 * the next time though.
680 	 *
681 	 * If the extent we found is inside our range, we clear
682 	 * the desired bit on it.
683 	 */
684 
685 	if (state->start < start) {
686 		prealloc = alloc_extent_state_atomic(prealloc);
687 		BUG_ON(!prealloc);
688 		err = split_state(tree, state, prealloc, start);
689 		if (err)
690 			extent_io_tree_panic(tree, err);
691 
692 		prealloc = NULL;
693 		if (err)
694 			goto out;
695 		if (state->end <= end) {
696 			state = clear_state_bit(tree, state, &bits, wake,
697 						changeset);
698 			goto next;
699 		}
700 		goto search_again;
701 	}
702 	/*
703 	 * | ---- desired range ---- |
704 	 *                        | state |
705 	 * We need to split the extent, and clear the bit
706 	 * on the first half
707 	 */
708 	if (state->start <= end && state->end > end) {
709 		prealloc = alloc_extent_state_atomic(prealloc);
710 		BUG_ON(!prealloc);
711 		err = split_state(tree, state, prealloc, end + 1);
712 		if (err)
713 			extent_io_tree_panic(tree, err);
714 
715 		if (wake)
716 			wake_up(&state->wq);
717 
718 		clear_state_bit(tree, prealloc, &bits, wake, changeset);
719 
720 		prealloc = NULL;
721 		goto out;
722 	}
723 
724 	state = clear_state_bit(tree, state, &bits, wake, changeset);
725 next:
726 	if (last_end == (u64)-1)
727 		goto out;
728 	start = last_end + 1;
729 	if (start <= end && state && !need_resched())
730 		goto hit_next;
731 	goto search_again;
732 
733 out:
734 	spin_unlock(&tree->lock);
735 	if (prealloc)
736 		free_extent_state(prealloc);
737 
738 	return 0;
739 
740 search_again:
741 	if (start > end)
742 		goto out;
743 	spin_unlock(&tree->lock);
744 	if (gfpflags_allow_blocking(mask))
745 		cond_resched();
746 	goto again;
747 }
748 
749 static void wait_on_state(struct extent_io_tree *tree,
750 			  struct extent_state *state)
751 		__releases(tree->lock)
752 		__acquires(tree->lock)
753 {
754 	DEFINE_WAIT(wait);
755 	prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
756 	spin_unlock(&tree->lock);
757 	schedule();
758 	spin_lock(&tree->lock);
759 	finish_wait(&state->wq, &wait);
760 }
761 
762 /*
763  * waits for one or more bits to clear on a range in the state tree.
764  * The range [start, end] is inclusive.
765  * The tree lock is taken by this function
766  */
767 static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
768 			    unsigned long bits)
769 {
770 	struct extent_state *state;
771 	struct rb_node *node;
772 
773 	btrfs_debug_check_extent_io_range(tree, start, end);
774 
775 	spin_lock(&tree->lock);
776 again:
777 	while (1) {
778 		/*
779 		 * this search will find all the extents that end after
780 		 * our range starts
781 		 */
782 		node = tree_search(tree, start);
783 process_node:
784 		if (!node)
785 			break;
786 
787 		state = rb_entry(node, struct extent_state, rb_node);
788 
789 		if (state->start > end)
790 			goto out;
791 
792 		if (state->state & bits) {
793 			start = state->start;
794 			atomic_inc(&state->refs);
795 			wait_on_state(tree, state);
796 			free_extent_state(state);
797 			goto again;
798 		}
799 		start = state->end + 1;
800 
801 		if (start > end)
802 			break;
803 
804 		if (!cond_resched_lock(&tree->lock)) {
805 			node = rb_next(node);
806 			goto process_node;
807 		}
808 	}
809 out:
810 	spin_unlock(&tree->lock);
811 }
812 
813 static void set_state_bits(struct extent_io_tree *tree,
814 			   struct extent_state *state,
815 			   unsigned *bits, struct extent_changeset *changeset)
816 {
817 	unsigned bits_to_set = *bits & ~EXTENT_CTLBITS;
818 
819 	set_state_cb(tree, state, bits);
820 	if ((bits_to_set & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
821 		u64 range = state->end - state->start + 1;
822 		tree->dirty_bytes += range;
823 	}
824 	add_extent_changeset(state, bits_to_set, changeset, 1);
825 	state->state |= bits_to_set;
826 }
827 
828 static void cache_state_if_flags(struct extent_state *state,
829 				 struct extent_state **cached_ptr,
830 				 unsigned flags)
831 {
832 	if (cached_ptr && !(*cached_ptr)) {
833 		if (!flags || (state->state & flags)) {
834 			*cached_ptr = state;
835 			atomic_inc(&state->refs);
836 		}
837 	}
838 }
839 
840 static void cache_state(struct extent_state *state,
841 			struct extent_state **cached_ptr)
842 {
843 	return cache_state_if_flags(state, cached_ptr,
844 				    EXTENT_IOBITS | EXTENT_BOUNDARY);
845 }
846 
847 /*
848  * set some bits on a range in the tree.  This may require allocations or
849  * sleeping, so the gfp mask is used to indicate what is allowed.
850  *
851  * If any of the exclusive bits are set, this will fail with -EEXIST if some
852  * part of the range already has the desired bits set.  The start of the
853  * existing range is returned in failed_start in this case.
854  *
855  * [start, end] is inclusive This takes the tree lock.
856  */
857 
858 static int __must_check
859 __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
860 		 unsigned bits, unsigned exclusive_bits,
861 		 u64 *failed_start, struct extent_state **cached_state,
862 		 gfp_t mask, struct extent_changeset *changeset)
863 {
864 	struct extent_state *state;
865 	struct extent_state *prealloc = NULL;
866 	struct rb_node *node;
867 	struct rb_node **p;
868 	struct rb_node *parent;
869 	int err = 0;
870 	u64 last_start;
871 	u64 last_end;
872 
873 	btrfs_debug_check_extent_io_range(tree, start, end);
874 
875 	bits |= EXTENT_FIRST_DELALLOC;
876 again:
877 	if (!prealloc && gfpflags_allow_blocking(mask)) {
878 		prealloc = alloc_extent_state(mask);
879 		BUG_ON(!prealloc);
880 	}
881 
882 	spin_lock(&tree->lock);
883 	if (cached_state && *cached_state) {
884 		state = *cached_state;
885 		if (state->start <= start && state->end > start &&
886 		    extent_state_in_tree(state)) {
887 			node = &state->rb_node;
888 			goto hit_next;
889 		}
890 	}
891 	/*
892 	 * this search will find all the extents that end after
893 	 * our range starts.
894 	 */
895 	node = tree_search_for_insert(tree, start, &p, &parent);
896 	if (!node) {
897 		prealloc = alloc_extent_state_atomic(prealloc);
898 		BUG_ON(!prealloc);
899 		err = insert_state(tree, prealloc, start, end,
900 				   &p, &parent, &bits, changeset);
901 		if (err)
902 			extent_io_tree_panic(tree, err);
903 
904 		cache_state(prealloc, cached_state);
905 		prealloc = NULL;
906 		goto out;
907 	}
908 	state = rb_entry(node, struct extent_state, rb_node);
909 hit_next:
910 	last_start = state->start;
911 	last_end = state->end;
912 
913 	/*
914 	 * | ---- desired range ---- |
915 	 * | state |
916 	 *
917 	 * Just lock what we found and keep going
918 	 */
919 	if (state->start == start && state->end <= end) {
920 		if (state->state & exclusive_bits) {
921 			*failed_start = state->start;
922 			err = -EEXIST;
923 			goto out;
924 		}
925 
926 		set_state_bits(tree, state, &bits, changeset);
927 		cache_state(state, cached_state);
928 		merge_state(tree, state);
929 		if (last_end == (u64)-1)
930 			goto out;
931 		start = last_end + 1;
932 		state = next_state(state);
933 		if (start < end && state && state->start == start &&
934 		    !need_resched())
935 			goto hit_next;
936 		goto search_again;
937 	}
938 
939 	/*
940 	 *     | ---- desired range ---- |
941 	 * | state |
942 	 *   or
943 	 * | ------------- state -------------- |
944 	 *
945 	 * We need to split the extent we found, and may flip bits on
946 	 * second half.
947 	 *
948 	 * If the extent we found extends past our
949 	 * range, we just split and search again.  It'll get split
950 	 * again the next time though.
951 	 *
952 	 * If the extent we found is inside our range, we set the
953 	 * desired bit on it.
954 	 */
955 	if (state->start < start) {
956 		if (state->state & exclusive_bits) {
957 			*failed_start = start;
958 			err = -EEXIST;
959 			goto out;
960 		}
961 
962 		prealloc = alloc_extent_state_atomic(prealloc);
963 		BUG_ON(!prealloc);
964 		err = split_state(tree, state, prealloc, start);
965 		if (err)
966 			extent_io_tree_panic(tree, err);
967 
968 		prealloc = NULL;
969 		if (err)
970 			goto out;
971 		if (state->end <= end) {
972 			set_state_bits(tree, state, &bits, changeset);
973 			cache_state(state, cached_state);
974 			merge_state(tree, state);
975 			if (last_end == (u64)-1)
976 				goto out;
977 			start = last_end + 1;
978 			state = next_state(state);
979 			if (start < end && state && state->start == start &&
980 			    !need_resched())
981 				goto hit_next;
982 		}
983 		goto search_again;
984 	}
985 	/*
986 	 * | ---- desired range ---- |
987 	 *     | state | or               | state |
988 	 *
989 	 * There's a hole, we need to insert something in it and
990 	 * ignore the extent we found.
991 	 */
992 	if (state->start > start) {
993 		u64 this_end;
994 		if (end < last_start)
995 			this_end = end;
996 		else
997 			this_end = last_start - 1;
998 
999 		prealloc = alloc_extent_state_atomic(prealloc);
1000 		BUG_ON(!prealloc);
1001 
1002 		/*
1003 		 * Avoid to free 'prealloc' if it can be merged with
1004 		 * the later extent.
1005 		 */
1006 		err = insert_state(tree, prealloc, start, this_end,
1007 				   NULL, NULL, &bits, changeset);
1008 		if (err)
1009 			extent_io_tree_panic(tree, err);
1010 
1011 		cache_state(prealloc, cached_state);
1012 		prealloc = NULL;
1013 		start = this_end + 1;
1014 		goto search_again;
1015 	}
1016 	/*
1017 	 * | ---- desired range ---- |
1018 	 *                        | state |
1019 	 * We need to split the extent, and set the bit
1020 	 * on the first half
1021 	 */
1022 	if (state->start <= end && state->end > end) {
1023 		if (state->state & exclusive_bits) {
1024 			*failed_start = start;
1025 			err = -EEXIST;
1026 			goto out;
1027 		}
1028 
1029 		prealloc = alloc_extent_state_atomic(prealloc);
1030 		BUG_ON(!prealloc);
1031 		err = split_state(tree, state, prealloc, end + 1);
1032 		if (err)
1033 			extent_io_tree_panic(tree, err);
1034 
1035 		set_state_bits(tree, prealloc, &bits, changeset);
1036 		cache_state(prealloc, cached_state);
1037 		merge_state(tree, prealloc);
1038 		prealloc = NULL;
1039 		goto out;
1040 	}
1041 
1042 	goto search_again;
1043 
1044 out:
1045 	spin_unlock(&tree->lock);
1046 	if (prealloc)
1047 		free_extent_state(prealloc);
1048 
1049 	return err;
1050 
1051 search_again:
1052 	if (start > end)
1053 		goto out;
1054 	spin_unlock(&tree->lock);
1055 	if (gfpflags_allow_blocking(mask))
1056 		cond_resched();
1057 	goto again;
1058 }
1059 
1060 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1061 		   unsigned bits, u64 * failed_start,
1062 		   struct extent_state **cached_state, gfp_t mask)
1063 {
1064 	return __set_extent_bit(tree, start, end, bits, 0, failed_start,
1065 				cached_state, mask, NULL);
1066 }
1067 
1068 
1069 /**
1070  * convert_extent_bit - convert all bits in a given range from one bit to
1071  * 			another
1072  * @tree:	the io tree to search
1073  * @start:	the start offset in bytes
1074  * @end:	the end offset in bytes (inclusive)
1075  * @bits:	the bits to set in this range
1076  * @clear_bits:	the bits to clear in this range
1077  * @cached_state:	state that we're going to cache
1078  * @mask:	the allocation mask
1079  *
1080  * This will go through and set bits for the given range.  If any states exist
1081  * already in this range they are set with the given bit and cleared of the
1082  * clear_bits.  This is only meant to be used by things that are mergeable, ie
1083  * converting from say DELALLOC to DIRTY.  This is not meant to be used with
1084  * boundary bits like LOCK.
1085  */
1086 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1087 		       unsigned bits, unsigned clear_bits,
1088 		       struct extent_state **cached_state, gfp_t mask)
1089 {
1090 	struct extent_state *state;
1091 	struct extent_state *prealloc = NULL;
1092 	struct rb_node *node;
1093 	struct rb_node **p;
1094 	struct rb_node *parent;
1095 	int err = 0;
1096 	u64 last_start;
1097 	u64 last_end;
1098 	bool first_iteration = true;
1099 
1100 	btrfs_debug_check_extent_io_range(tree, start, end);
1101 
1102 again:
1103 	if (!prealloc && gfpflags_allow_blocking(mask)) {
1104 		/*
1105 		 * Best effort, don't worry if extent state allocation fails
1106 		 * here for the first iteration. We might have a cached state
1107 		 * that matches exactly the target range, in which case no
1108 		 * extent state allocations are needed. We'll only know this
1109 		 * after locking the tree.
1110 		 */
1111 		prealloc = alloc_extent_state(mask);
1112 		if (!prealloc && !first_iteration)
1113 			return -ENOMEM;
1114 	}
1115 
1116 	spin_lock(&tree->lock);
1117 	if (cached_state && *cached_state) {
1118 		state = *cached_state;
1119 		if (state->start <= start && state->end > start &&
1120 		    extent_state_in_tree(state)) {
1121 			node = &state->rb_node;
1122 			goto hit_next;
1123 		}
1124 	}
1125 
1126 	/*
1127 	 * this search will find all the extents that end after
1128 	 * our range starts.
1129 	 */
1130 	node = tree_search_for_insert(tree, start, &p, &parent);
1131 	if (!node) {
1132 		prealloc = alloc_extent_state_atomic(prealloc);
1133 		if (!prealloc) {
1134 			err = -ENOMEM;
1135 			goto out;
1136 		}
1137 		err = insert_state(tree, prealloc, start, end,
1138 				   &p, &parent, &bits, NULL);
1139 		if (err)
1140 			extent_io_tree_panic(tree, err);
1141 		cache_state(prealloc, cached_state);
1142 		prealloc = NULL;
1143 		goto out;
1144 	}
1145 	state = rb_entry(node, struct extent_state, rb_node);
1146 hit_next:
1147 	last_start = state->start;
1148 	last_end = state->end;
1149 
1150 	/*
1151 	 * | ---- desired range ---- |
1152 	 * | state |
1153 	 *
1154 	 * Just lock what we found and keep going
1155 	 */
1156 	if (state->start == start && state->end <= end) {
1157 		set_state_bits(tree, state, &bits, NULL);
1158 		cache_state(state, cached_state);
1159 		state = clear_state_bit(tree, state, &clear_bits, 0, NULL);
1160 		if (last_end == (u64)-1)
1161 			goto out;
1162 		start = last_end + 1;
1163 		if (start < end && state && state->start == start &&
1164 		    !need_resched())
1165 			goto hit_next;
1166 		goto search_again;
1167 	}
1168 
1169 	/*
1170 	 *     | ---- desired range ---- |
1171 	 * | state |
1172 	 *   or
1173 	 * | ------------- state -------------- |
1174 	 *
1175 	 * We need to split the extent we found, and may flip bits on
1176 	 * second half.
1177 	 *
1178 	 * If the extent we found extends past our
1179 	 * range, we just split and search again.  It'll get split
1180 	 * again the next time though.
1181 	 *
1182 	 * If the extent we found is inside our range, we set the
1183 	 * desired bit on it.
1184 	 */
1185 	if (state->start < start) {
1186 		prealloc = alloc_extent_state_atomic(prealloc);
1187 		if (!prealloc) {
1188 			err = -ENOMEM;
1189 			goto out;
1190 		}
1191 		err = split_state(tree, state, prealloc, start);
1192 		if (err)
1193 			extent_io_tree_panic(tree, err);
1194 		prealloc = NULL;
1195 		if (err)
1196 			goto out;
1197 		if (state->end <= end) {
1198 			set_state_bits(tree, state, &bits, NULL);
1199 			cache_state(state, cached_state);
1200 			state = clear_state_bit(tree, state, &clear_bits, 0,
1201 						NULL);
1202 			if (last_end == (u64)-1)
1203 				goto out;
1204 			start = last_end + 1;
1205 			if (start < end && state && state->start == start &&
1206 			    !need_resched())
1207 				goto hit_next;
1208 		}
1209 		goto search_again;
1210 	}
1211 	/*
1212 	 * | ---- desired range ---- |
1213 	 *     | state | or               | state |
1214 	 *
1215 	 * There's a hole, we need to insert something in it and
1216 	 * ignore the extent we found.
1217 	 */
1218 	if (state->start > start) {
1219 		u64 this_end;
1220 		if (end < last_start)
1221 			this_end = end;
1222 		else
1223 			this_end = last_start - 1;
1224 
1225 		prealloc = alloc_extent_state_atomic(prealloc);
1226 		if (!prealloc) {
1227 			err = -ENOMEM;
1228 			goto out;
1229 		}
1230 
1231 		/*
1232 		 * Avoid to free 'prealloc' if it can be merged with
1233 		 * the later extent.
1234 		 */
1235 		err = insert_state(tree, prealloc, start, this_end,
1236 				   NULL, NULL, &bits, NULL);
1237 		if (err)
1238 			extent_io_tree_panic(tree, err);
1239 		cache_state(prealloc, cached_state);
1240 		prealloc = NULL;
1241 		start = this_end + 1;
1242 		goto search_again;
1243 	}
1244 	/*
1245 	 * | ---- desired range ---- |
1246 	 *                        | state |
1247 	 * We need to split the extent, and set the bit
1248 	 * on the first half
1249 	 */
1250 	if (state->start <= end && state->end > end) {
1251 		prealloc = alloc_extent_state_atomic(prealloc);
1252 		if (!prealloc) {
1253 			err = -ENOMEM;
1254 			goto out;
1255 		}
1256 
1257 		err = split_state(tree, state, prealloc, end + 1);
1258 		if (err)
1259 			extent_io_tree_panic(tree, err);
1260 
1261 		set_state_bits(tree, prealloc, &bits, NULL);
1262 		cache_state(prealloc, cached_state);
1263 		clear_state_bit(tree, prealloc, &clear_bits, 0, NULL);
1264 		prealloc = NULL;
1265 		goto out;
1266 	}
1267 
1268 	goto search_again;
1269 
1270 out:
1271 	spin_unlock(&tree->lock);
1272 	if (prealloc)
1273 		free_extent_state(prealloc);
1274 
1275 	return err;
1276 
1277 search_again:
1278 	if (start > end)
1279 		goto out;
1280 	spin_unlock(&tree->lock);
1281 	if (gfpflags_allow_blocking(mask))
1282 		cond_resched();
1283 	first_iteration = false;
1284 	goto again;
1285 }
1286 
1287 /* wrappers around set/clear extent bit */
1288 int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
1289 		     gfp_t mask)
1290 {
1291 	return set_extent_bit(tree, start, end, EXTENT_DIRTY, NULL,
1292 			      NULL, mask);
1293 }
1294 
1295 int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1296 		    unsigned bits, gfp_t mask)
1297 {
1298 	return set_extent_bit(tree, start, end, bits, NULL,
1299 			      NULL, mask);
1300 }
1301 
1302 int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1303 			   unsigned bits, gfp_t mask,
1304 			   struct extent_changeset *changeset)
1305 {
1306 	/*
1307 	 * We don't support EXTENT_LOCKED yet, as current changeset will
1308 	 * record any bits changed, so for EXTENT_LOCKED case, it will
1309 	 * either fail with -EEXIST or changeset will record the whole
1310 	 * range.
1311 	 */
1312 	BUG_ON(bits & EXTENT_LOCKED);
1313 
1314 	return __set_extent_bit(tree, start, end, bits, 0, NULL, NULL, mask,
1315 				changeset);
1316 }
1317 
1318 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
1319 		     unsigned bits, int wake, int delete,
1320 		     struct extent_state **cached, gfp_t mask)
1321 {
1322 	return __clear_extent_bit(tree, start, end, bits, wake, delete,
1323 				  cached, mask, NULL);
1324 }
1325 
1326 int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1327 		      unsigned bits, gfp_t mask)
1328 {
1329 	int wake = 0;
1330 
1331 	if (bits & EXTENT_LOCKED)
1332 		wake = 1;
1333 
1334 	return clear_extent_bit(tree, start, end, bits, wake, 0, NULL, mask);
1335 }
1336 
1337 int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1338 			     unsigned bits, gfp_t mask,
1339 			     struct extent_changeset *changeset)
1340 {
1341 	/*
1342 	 * Don't support EXTENT_LOCKED case, same reason as
1343 	 * set_record_extent_bits().
1344 	 */
1345 	BUG_ON(bits & EXTENT_LOCKED);
1346 
1347 	return __clear_extent_bit(tree, start, end, bits, 0, 0, NULL, mask,
1348 				  changeset);
1349 }
1350 
1351 int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
1352 			struct extent_state **cached_state, gfp_t mask)
1353 {
1354 	return set_extent_bit(tree, start, end,
1355 			      EXTENT_DELALLOC | EXTENT_UPTODATE,
1356 			      NULL, cached_state, mask);
1357 }
1358 
1359 int set_extent_defrag(struct extent_io_tree *tree, u64 start, u64 end,
1360 		      struct extent_state **cached_state, gfp_t mask)
1361 {
1362 	return set_extent_bit(tree, start, end,
1363 			      EXTENT_DELALLOC | EXTENT_UPTODATE | EXTENT_DEFRAG,
1364 			      NULL, cached_state, mask);
1365 }
1366 
1367 int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
1368 		       gfp_t mask)
1369 {
1370 	return clear_extent_bit(tree, start, end,
1371 				EXTENT_DIRTY | EXTENT_DELALLOC |
1372 				EXTENT_DO_ACCOUNTING, 0, 0, NULL, mask);
1373 }
1374 
1375 int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
1376 		     gfp_t mask)
1377 {
1378 	return set_extent_bit(tree, start, end, EXTENT_NEW, NULL,
1379 			      NULL, mask);
1380 }
1381 
1382 int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
1383 			struct extent_state **cached_state, gfp_t mask)
1384 {
1385 	return set_extent_bit(tree, start, end, EXTENT_UPTODATE, NULL,
1386 			      cached_state, mask);
1387 }
1388 
1389 int clear_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
1390 			  struct extent_state **cached_state, gfp_t mask)
1391 {
1392 	return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
1393 				cached_state, mask);
1394 }
1395 
1396 /*
1397  * either insert or lock state struct between start and end use mask to tell
1398  * us if waiting is desired.
1399  */
1400 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
1401 		     unsigned bits, struct extent_state **cached_state)
1402 {
1403 	int err;
1404 	u64 failed_start;
1405 
1406 	while (1) {
1407 		err = __set_extent_bit(tree, start, end, EXTENT_LOCKED | bits,
1408 				       EXTENT_LOCKED, &failed_start,
1409 				       cached_state, GFP_NOFS, NULL);
1410 		if (err == -EEXIST) {
1411 			wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
1412 			start = failed_start;
1413 		} else
1414 			break;
1415 		WARN_ON(start > end);
1416 	}
1417 	return err;
1418 }
1419 
1420 int lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1421 {
1422 	return lock_extent_bits(tree, start, end, 0, NULL);
1423 }
1424 
1425 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1426 {
1427 	int err;
1428 	u64 failed_start;
1429 
1430 	err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, EXTENT_LOCKED,
1431 			       &failed_start, NULL, GFP_NOFS, NULL);
1432 	if (err == -EEXIST) {
1433 		if (failed_start > start)
1434 			clear_extent_bit(tree, start, failed_start - 1,
1435 					 EXTENT_LOCKED, 1, 0, NULL, GFP_NOFS);
1436 		return 0;
1437 	}
1438 	return 1;
1439 }
1440 
1441 int unlock_extent_cached(struct extent_io_tree *tree, u64 start, u64 end,
1442 			 struct extent_state **cached, gfp_t mask)
1443 {
1444 	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
1445 				mask);
1446 }
1447 
1448 int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end)
1449 {
1450 	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL,
1451 				GFP_NOFS);
1452 }
1453 
1454 int extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
1455 {
1456 	unsigned long index = start >> PAGE_CACHE_SHIFT;
1457 	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1458 	struct page *page;
1459 
1460 	while (index <= end_index) {
1461 		page = find_get_page(inode->i_mapping, index);
1462 		BUG_ON(!page); /* Pages should be in the extent_io_tree */
1463 		clear_page_dirty_for_io(page);
1464 		page_cache_release(page);
1465 		index++;
1466 	}
1467 	return 0;
1468 }
1469 
1470 int extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
1471 {
1472 	unsigned long index = start >> PAGE_CACHE_SHIFT;
1473 	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1474 	struct page *page;
1475 
1476 	while (index <= end_index) {
1477 		page = find_get_page(inode->i_mapping, index);
1478 		BUG_ON(!page); /* Pages should be in the extent_io_tree */
1479 		__set_page_dirty_nobuffers(page);
1480 		account_page_redirty(page);
1481 		page_cache_release(page);
1482 		index++;
1483 	}
1484 	return 0;
1485 }
1486 
1487 /*
1488  * helper function to set both pages and extents in the tree writeback
1489  */
1490 static int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
1491 {
1492 	unsigned long index = start >> PAGE_CACHE_SHIFT;
1493 	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1494 	struct page *page;
1495 
1496 	while (index <= end_index) {
1497 		page = find_get_page(tree->mapping, index);
1498 		BUG_ON(!page); /* Pages should be in the extent_io_tree */
1499 		set_page_writeback(page);
1500 		page_cache_release(page);
1501 		index++;
1502 	}
1503 	return 0;
1504 }
1505 
1506 /* find the first state struct with 'bits' set after 'start', and
1507  * return it.  tree->lock must be held.  NULL will returned if
1508  * nothing was found after 'start'
1509  */
1510 static struct extent_state *
1511 find_first_extent_bit_state(struct extent_io_tree *tree,
1512 			    u64 start, unsigned bits)
1513 {
1514 	struct rb_node *node;
1515 	struct extent_state *state;
1516 
1517 	/*
1518 	 * this search will find all the extents that end after
1519 	 * our range starts.
1520 	 */
1521 	node = tree_search(tree, start);
1522 	if (!node)
1523 		goto out;
1524 
1525 	while (1) {
1526 		state = rb_entry(node, struct extent_state, rb_node);
1527 		if (state->end >= start && (state->state & bits))
1528 			return state;
1529 
1530 		node = rb_next(node);
1531 		if (!node)
1532 			break;
1533 	}
1534 out:
1535 	return NULL;
1536 }
1537 
1538 /*
1539  * find the first offset in the io tree with 'bits' set. zero is
1540  * returned if we find something, and *start_ret and *end_ret are
1541  * set to reflect the state struct that was found.
1542  *
1543  * If nothing was found, 1 is returned. If found something, return 0.
1544  */
1545 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
1546 			  u64 *start_ret, u64 *end_ret, unsigned bits,
1547 			  struct extent_state **cached_state)
1548 {
1549 	struct extent_state *state;
1550 	struct rb_node *n;
1551 	int ret = 1;
1552 
1553 	spin_lock(&tree->lock);
1554 	if (cached_state && *cached_state) {
1555 		state = *cached_state;
1556 		if (state->end == start - 1 && extent_state_in_tree(state)) {
1557 			n = rb_next(&state->rb_node);
1558 			while (n) {
1559 				state = rb_entry(n, struct extent_state,
1560 						 rb_node);
1561 				if (state->state & bits)
1562 					goto got_it;
1563 				n = rb_next(n);
1564 			}
1565 			free_extent_state(*cached_state);
1566 			*cached_state = NULL;
1567 			goto out;
1568 		}
1569 		free_extent_state(*cached_state);
1570 		*cached_state = NULL;
1571 	}
1572 
1573 	state = find_first_extent_bit_state(tree, start, bits);
1574 got_it:
1575 	if (state) {
1576 		cache_state_if_flags(state, cached_state, 0);
1577 		*start_ret = state->start;
1578 		*end_ret = state->end;
1579 		ret = 0;
1580 	}
1581 out:
1582 	spin_unlock(&tree->lock);
1583 	return ret;
1584 }
1585 
1586 /*
1587  * find a contiguous range of bytes in the file marked as delalloc, not
1588  * more than 'max_bytes'.  start and end are used to return the range,
1589  *
1590  * 1 is returned if we find something, 0 if nothing was in the tree
1591  */
1592 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
1593 					u64 *start, u64 *end, u64 max_bytes,
1594 					struct extent_state **cached_state)
1595 {
1596 	struct rb_node *node;
1597 	struct extent_state *state;
1598 	u64 cur_start = *start;
1599 	u64 found = 0;
1600 	u64 total_bytes = 0;
1601 
1602 	spin_lock(&tree->lock);
1603 
1604 	/*
1605 	 * this search will find all the extents that end after
1606 	 * our range starts.
1607 	 */
1608 	node = tree_search(tree, cur_start);
1609 	if (!node) {
1610 		if (!found)
1611 			*end = (u64)-1;
1612 		goto out;
1613 	}
1614 
1615 	while (1) {
1616 		state = rb_entry(node, struct extent_state, rb_node);
1617 		if (found && (state->start != cur_start ||
1618 			      (state->state & EXTENT_BOUNDARY))) {
1619 			goto out;
1620 		}
1621 		if (!(state->state & EXTENT_DELALLOC)) {
1622 			if (!found)
1623 				*end = state->end;
1624 			goto out;
1625 		}
1626 		if (!found) {
1627 			*start = state->start;
1628 			*cached_state = state;
1629 			atomic_inc(&state->refs);
1630 		}
1631 		found++;
1632 		*end = state->end;
1633 		cur_start = state->end + 1;
1634 		node = rb_next(node);
1635 		total_bytes += state->end - state->start + 1;
1636 		if (total_bytes >= max_bytes)
1637 			break;
1638 		if (!node)
1639 			break;
1640 	}
1641 out:
1642 	spin_unlock(&tree->lock);
1643 	return found;
1644 }
1645 
1646 static noinline void __unlock_for_delalloc(struct inode *inode,
1647 					   struct page *locked_page,
1648 					   u64 start, u64 end)
1649 {
1650 	int ret;
1651 	struct page *pages[16];
1652 	unsigned long index = start >> PAGE_CACHE_SHIFT;
1653 	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1654 	unsigned long nr_pages = end_index - index + 1;
1655 	int i;
1656 
1657 	if (index == locked_page->index && end_index == index)
1658 		return;
1659 
1660 	while (nr_pages > 0) {
1661 		ret = find_get_pages_contig(inode->i_mapping, index,
1662 				     min_t(unsigned long, nr_pages,
1663 				     ARRAY_SIZE(pages)), pages);
1664 		for (i = 0; i < ret; i++) {
1665 			if (pages[i] != locked_page)
1666 				unlock_page(pages[i]);
1667 			page_cache_release(pages[i]);
1668 		}
1669 		nr_pages -= ret;
1670 		index += ret;
1671 		cond_resched();
1672 	}
1673 }
1674 
1675 static noinline int lock_delalloc_pages(struct inode *inode,
1676 					struct page *locked_page,
1677 					u64 delalloc_start,
1678 					u64 delalloc_end)
1679 {
1680 	unsigned long index = delalloc_start >> PAGE_CACHE_SHIFT;
1681 	unsigned long start_index = index;
1682 	unsigned long end_index = delalloc_end >> PAGE_CACHE_SHIFT;
1683 	unsigned long pages_locked = 0;
1684 	struct page *pages[16];
1685 	unsigned long nrpages;
1686 	int ret;
1687 	int i;
1688 
1689 	/* the caller is responsible for locking the start index */
1690 	if (index == locked_page->index && index == end_index)
1691 		return 0;
1692 
1693 	/* skip the page at the start index */
1694 	nrpages = end_index - index + 1;
1695 	while (nrpages > 0) {
1696 		ret = find_get_pages_contig(inode->i_mapping, index,
1697 				     min_t(unsigned long,
1698 				     nrpages, ARRAY_SIZE(pages)), pages);
1699 		if (ret == 0) {
1700 			ret = -EAGAIN;
1701 			goto done;
1702 		}
1703 		/* now we have an array of pages, lock them all */
1704 		for (i = 0; i < ret; i++) {
1705 			/*
1706 			 * the caller is taking responsibility for
1707 			 * locked_page
1708 			 */
1709 			if (pages[i] != locked_page) {
1710 				lock_page(pages[i]);
1711 				if (!PageDirty(pages[i]) ||
1712 				    pages[i]->mapping != inode->i_mapping) {
1713 					ret = -EAGAIN;
1714 					unlock_page(pages[i]);
1715 					page_cache_release(pages[i]);
1716 					goto done;
1717 				}
1718 			}
1719 			page_cache_release(pages[i]);
1720 			pages_locked++;
1721 		}
1722 		nrpages -= ret;
1723 		index += ret;
1724 		cond_resched();
1725 	}
1726 	ret = 0;
1727 done:
1728 	if (ret && pages_locked) {
1729 		__unlock_for_delalloc(inode, locked_page,
1730 			      delalloc_start,
1731 			      ((u64)(start_index + pages_locked - 1)) <<
1732 			      PAGE_CACHE_SHIFT);
1733 	}
1734 	return ret;
1735 }
1736 
1737 /*
1738  * find a contiguous range of bytes in the file marked as delalloc, not
1739  * more than 'max_bytes'.  start and end are used to return the range,
1740  *
1741  * 1 is returned if we find something, 0 if nothing was in the tree
1742  */
1743 STATIC u64 find_lock_delalloc_range(struct inode *inode,
1744 				    struct extent_io_tree *tree,
1745 				    struct page *locked_page, u64 *start,
1746 				    u64 *end, u64 max_bytes)
1747 {
1748 	u64 delalloc_start;
1749 	u64 delalloc_end;
1750 	u64 found;
1751 	struct extent_state *cached_state = NULL;
1752 	int ret;
1753 	int loops = 0;
1754 
1755 again:
1756 	/* step one, find a bunch of delalloc bytes starting at start */
1757 	delalloc_start = *start;
1758 	delalloc_end = 0;
1759 	found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
1760 				    max_bytes, &cached_state);
1761 	if (!found || delalloc_end <= *start) {
1762 		*start = delalloc_start;
1763 		*end = delalloc_end;
1764 		free_extent_state(cached_state);
1765 		return 0;
1766 	}
1767 
1768 	/*
1769 	 * start comes from the offset of locked_page.  We have to lock
1770 	 * pages in order, so we can't process delalloc bytes before
1771 	 * locked_page
1772 	 */
1773 	if (delalloc_start < *start)
1774 		delalloc_start = *start;
1775 
1776 	/*
1777 	 * make sure to limit the number of pages we try to lock down
1778 	 */
1779 	if (delalloc_end + 1 - delalloc_start > max_bytes)
1780 		delalloc_end = delalloc_start + max_bytes - 1;
1781 
1782 	/* step two, lock all the pages after the page that has start */
1783 	ret = lock_delalloc_pages(inode, locked_page,
1784 				  delalloc_start, delalloc_end);
1785 	if (ret == -EAGAIN) {
1786 		/* some of the pages are gone, lets avoid looping by
1787 		 * shortening the size of the delalloc range we're searching
1788 		 */
1789 		free_extent_state(cached_state);
1790 		cached_state = NULL;
1791 		if (!loops) {
1792 			max_bytes = PAGE_CACHE_SIZE;
1793 			loops = 1;
1794 			goto again;
1795 		} else {
1796 			found = 0;
1797 			goto out_failed;
1798 		}
1799 	}
1800 	BUG_ON(ret); /* Only valid values are 0 and -EAGAIN */
1801 
1802 	/* step three, lock the state bits for the whole range */
1803 	lock_extent_bits(tree, delalloc_start, delalloc_end, 0, &cached_state);
1804 
1805 	/* then test to make sure it is all still delalloc */
1806 	ret = test_range_bit(tree, delalloc_start, delalloc_end,
1807 			     EXTENT_DELALLOC, 1, cached_state);
1808 	if (!ret) {
1809 		unlock_extent_cached(tree, delalloc_start, delalloc_end,
1810 				     &cached_state, GFP_NOFS);
1811 		__unlock_for_delalloc(inode, locked_page,
1812 			      delalloc_start, delalloc_end);
1813 		cond_resched();
1814 		goto again;
1815 	}
1816 	free_extent_state(cached_state);
1817 	*start = delalloc_start;
1818 	*end = delalloc_end;
1819 out_failed:
1820 	return found;
1821 }
1822 
1823 int extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
1824 				 struct page *locked_page,
1825 				 unsigned clear_bits,
1826 				 unsigned long page_ops)
1827 {
1828 	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
1829 	int ret;
1830 	struct page *pages[16];
1831 	unsigned long index = start >> PAGE_CACHE_SHIFT;
1832 	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
1833 	unsigned long nr_pages = end_index - index + 1;
1834 	int i;
1835 
1836 	clear_extent_bit(tree, start, end, clear_bits, 1, 0, NULL, GFP_NOFS);
1837 	if (page_ops == 0)
1838 		return 0;
1839 
1840 	if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
1841 		mapping_set_error(inode->i_mapping, -EIO);
1842 
1843 	while (nr_pages > 0) {
1844 		ret = find_get_pages_contig(inode->i_mapping, index,
1845 				     min_t(unsigned long,
1846 				     nr_pages, ARRAY_SIZE(pages)), pages);
1847 		for (i = 0; i < ret; i++) {
1848 
1849 			if (page_ops & PAGE_SET_PRIVATE2)
1850 				SetPagePrivate2(pages[i]);
1851 
1852 			if (pages[i] == locked_page) {
1853 				page_cache_release(pages[i]);
1854 				continue;
1855 			}
1856 			if (page_ops & PAGE_CLEAR_DIRTY)
1857 				clear_page_dirty_for_io(pages[i]);
1858 			if (page_ops & PAGE_SET_WRITEBACK)
1859 				set_page_writeback(pages[i]);
1860 			if (page_ops & PAGE_SET_ERROR)
1861 				SetPageError(pages[i]);
1862 			if (page_ops & PAGE_END_WRITEBACK)
1863 				end_page_writeback(pages[i]);
1864 			if (page_ops & PAGE_UNLOCK)
1865 				unlock_page(pages[i]);
1866 			page_cache_release(pages[i]);
1867 		}
1868 		nr_pages -= ret;
1869 		index += ret;
1870 		cond_resched();
1871 	}
1872 	return 0;
1873 }
1874 
1875 /*
1876  * count the number of bytes in the tree that have a given bit(s)
1877  * set.  This can be fairly slow, except for EXTENT_DIRTY which is
1878  * cached.  The total number found is returned.
1879  */
1880 u64 count_range_bits(struct extent_io_tree *tree,
1881 		     u64 *start, u64 search_end, u64 max_bytes,
1882 		     unsigned bits, int contig)
1883 {
1884 	struct rb_node *node;
1885 	struct extent_state *state;
1886 	u64 cur_start = *start;
1887 	u64 total_bytes = 0;
1888 	u64 last = 0;
1889 	int found = 0;
1890 
1891 	if (WARN_ON(search_end <= cur_start))
1892 		return 0;
1893 
1894 	spin_lock(&tree->lock);
1895 	if (cur_start == 0 && bits == EXTENT_DIRTY) {
1896 		total_bytes = tree->dirty_bytes;
1897 		goto out;
1898 	}
1899 	/*
1900 	 * this search will find all the extents that end after
1901 	 * our range starts.
1902 	 */
1903 	node = tree_search(tree, cur_start);
1904 	if (!node)
1905 		goto out;
1906 
1907 	while (1) {
1908 		state = rb_entry(node, struct extent_state, rb_node);
1909 		if (state->start > search_end)
1910 			break;
1911 		if (contig && found && state->start > last + 1)
1912 			break;
1913 		if (state->end >= cur_start && (state->state & bits) == bits) {
1914 			total_bytes += min(search_end, state->end) + 1 -
1915 				       max(cur_start, state->start);
1916 			if (total_bytes >= max_bytes)
1917 				break;
1918 			if (!found) {
1919 				*start = max(cur_start, state->start);
1920 				found = 1;
1921 			}
1922 			last = state->end;
1923 		} else if (contig && found) {
1924 			break;
1925 		}
1926 		node = rb_next(node);
1927 		if (!node)
1928 			break;
1929 	}
1930 out:
1931 	spin_unlock(&tree->lock);
1932 	return total_bytes;
1933 }
1934 
1935 /*
1936  * set the private field for a given byte offset in the tree.  If there isn't
1937  * an extent_state there already, this does nothing.
1938  */
1939 static int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
1940 {
1941 	struct rb_node *node;
1942 	struct extent_state *state;
1943 	int ret = 0;
1944 
1945 	spin_lock(&tree->lock);
1946 	/*
1947 	 * this search will find all the extents that end after
1948 	 * our range starts.
1949 	 */
1950 	node = tree_search(tree, start);
1951 	if (!node) {
1952 		ret = -ENOENT;
1953 		goto out;
1954 	}
1955 	state = rb_entry(node, struct extent_state, rb_node);
1956 	if (state->start != start) {
1957 		ret = -ENOENT;
1958 		goto out;
1959 	}
1960 	state->private = private;
1961 out:
1962 	spin_unlock(&tree->lock);
1963 	return ret;
1964 }
1965 
1966 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
1967 {
1968 	struct rb_node *node;
1969 	struct extent_state *state;
1970 	int ret = 0;
1971 
1972 	spin_lock(&tree->lock);
1973 	/*
1974 	 * this search will find all the extents that end after
1975 	 * our range starts.
1976 	 */
1977 	node = tree_search(tree, start);
1978 	if (!node) {
1979 		ret = -ENOENT;
1980 		goto out;
1981 	}
1982 	state = rb_entry(node, struct extent_state, rb_node);
1983 	if (state->start != start) {
1984 		ret = -ENOENT;
1985 		goto out;
1986 	}
1987 	*private = state->private;
1988 out:
1989 	spin_unlock(&tree->lock);
1990 	return ret;
1991 }
1992 
1993 /*
1994  * searches a range in the state tree for a given mask.
1995  * If 'filled' == 1, this returns 1 only if every extent in the tree
1996  * has the bits set.  Otherwise, 1 is returned if any bit in the
1997  * range is found set.
1998  */
1999 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
2000 		   unsigned bits, int filled, struct extent_state *cached)
2001 {
2002 	struct extent_state *state = NULL;
2003 	struct rb_node *node;
2004 	int bitset = 0;
2005 
2006 	spin_lock(&tree->lock);
2007 	if (cached && extent_state_in_tree(cached) && cached->start <= start &&
2008 	    cached->end > start)
2009 		node = &cached->rb_node;
2010 	else
2011 		node = tree_search(tree, start);
2012 	while (node && start <= end) {
2013 		state = rb_entry(node, struct extent_state, rb_node);
2014 
2015 		if (filled && state->start > start) {
2016 			bitset = 0;
2017 			break;
2018 		}
2019 
2020 		if (state->start > end)
2021 			break;
2022 
2023 		if (state->state & bits) {
2024 			bitset = 1;
2025 			if (!filled)
2026 				break;
2027 		} else if (filled) {
2028 			bitset = 0;
2029 			break;
2030 		}
2031 
2032 		if (state->end == (u64)-1)
2033 			break;
2034 
2035 		start = state->end + 1;
2036 		if (start > end)
2037 			break;
2038 		node = rb_next(node);
2039 		if (!node) {
2040 			if (filled)
2041 				bitset = 0;
2042 			break;
2043 		}
2044 	}
2045 	spin_unlock(&tree->lock);
2046 	return bitset;
2047 }
2048 
2049 /*
2050  * helper function to set a given page up to date if all the
2051  * extents in the tree for that page are up to date
2052  */
2053 static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
2054 {
2055 	u64 start = page_offset(page);
2056 	u64 end = start + PAGE_CACHE_SIZE - 1;
2057 	if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL))
2058 		SetPageUptodate(page);
2059 }
2060 
2061 int free_io_failure(struct inode *inode, struct io_failure_record *rec)
2062 {
2063 	int ret;
2064 	int err = 0;
2065 	struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2066 
2067 	set_state_private(failure_tree, rec->start, 0);
2068 	ret = clear_extent_bits(failure_tree, rec->start,
2069 				rec->start + rec->len - 1,
2070 				EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
2071 	if (ret)
2072 		err = ret;
2073 
2074 	ret = clear_extent_bits(&BTRFS_I(inode)->io_tree, rec->start,
2075 				rec->start + rec->len - 1,
2076 				EXTENT_DAMAGED, GFP_NOFS);
2077 	if (ret && !err)
2078 		err = ret;
2079 
2080 	kfree(rec);
2081 	return err;
2082 }
2083 
2084 /*
2085  * this bypasses the standard btrfs submit functions deliberately, as
2086  * the standard behavior is to write all copies in a raid setup. here we only
2087  * want to write the one bad copy. so we do the mapping for ourselves and issue
2088  * submit_bio directly.
2089  * to avoid any synchronization issues, wait for the data after writing, which
2090  * actually prevents the read that triggered the error from finishing.
2091  * currently, there can be no more than two copies of every data bit. thus,
2092  * exactly one rewrite is required.
2093  */
2094 int repair_io_failure(struct inode *inode, u64 start, u64 length, u64 logical,
2095 		      struct page *page, unsigned int pg_offset, int mirror_num)
2096 {
2097 	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2098 	struct bio *bio;
2099 	struct btrfs_device *dev;
2100 	u64 map_length = 0;
2101 	u64 sector;
2102 	struct btrfs_bio *bbio = NULL;
2103 	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
2104 	int ret;
2105 
2106 	ASSERT(!(fs_info->sb->s_flags & MS_RDONLY));
2107 	BUG_ON(!mirror_num);
2108 
2109 	/* we can't repair anything in raid56 yet */
2110 	if (btrfs_is_parity_mirror(map_tree, logical, length, mirror_num))
2111 		return 0;
2112 
2113 	bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2114 	if (!bio)
2115 		return -EIO;
2116 	bio->bi_iter.bi_size = 0;
2117 	map_length = length;
2118 
2119 	ret = btrfs_map_block(fs_info, WRITE, logical,
2120 			      &map_length, &bbio, mirror_num);
2121 	if (ret) {
2122 		bio_put(bio);
2123 		return -EIO;
2124 	}
2125 	BUG_ON(mirror_num != bbio->mirror_num);
2126 	sector = bbio->stripes[mirror_num-1].physical >> 9;
2127 	bio->bi_iter.bi_sector = sector;
2128 	dev = bbio->stripes[mirror_num-1].dev;
2129 	btrfs_put_bbio(bbio);
2130 	if (!dev || !dev->bdev || !dev->writeable) {
2131 		bio_put(bio);
2132 		return -EIO;
2133 	}
2134 	bio->bi_bdev = dev->bdev;
2135 	bio_add_page(bio, page, length, pg_offset);
2136 
2137 	if (btrfsic_submit_bio_wait(WRITE_SYNC, bio)) {
2138 		/* try to remap that extent elsewhere? */
2139 		bio_put(bio);
2140 		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
2141 		return -EIO;
2142 	}
2143 
2144 	btrfs_info_rl_in_rcu(fs_info,
2145 		"read error corrected: ino %llu off %llu (dev %s sector %llu)",
2146 				  btrfs_ino(inode), start,
2147 				  rcu_str_deref(dev->name), sector);
2148 	bio_put(bio);
2149 	return 0;
2150 }
2151 
2152 int repair_eb_io_failure(struct btrfs_root *root, struct extent_buffer *eb,
2153 			 int mirror_num)
2154 {
2155 	u64 start = eb->start;
2156 	unsigned long i, num_pages = num_extent_pages(eb->start, eb->len);
2157 	int ret = 0;
2158 
2159 	if (root->fs_info->sb->s_flags & MS_RDONLY)
2160 		return -EROFS;
2161 
2162 	for (i = 0; i < num_pages; i++) {
2163 		struct page *p = eb->pages[i];
2164 
2165 		ret = repair_io_failure(root->fs_info->btree_inode, start,
2166 					PAGE_CACHE_SIZE, start, p,
2167 					start - page_offset(p), mirror_num);
2168 		if (ret)
2169 			break;
2170 		start += PAGE_CACHE_SIZE;
2171 	}
2172 
2173 	return ret;
2174 }
2175 
2176 /*
2177  * each time an IO finishes, we do a fast check in the IO failure tree
2178  * to see if we need to process or clean up an io_failure_record
2179  */
2180 int clean_io_failure(struct inode *inode, u64 start, struct page *page,
2181 		     unsigned int pg_offset)
2182 {
2183 	u64 private;
2184 	u64 private_failure;
2185 	struct io_failure_record *failrec;
2186 	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2187 	struct extent_state *state;
2188 	int num_copies;
2189 	int ret;
2190 
2191 	private = 0;
2192 	ret = count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
2193 				(u64)-1, 1, EXTENT_DIRTY, 0);
2194 	if (!ret)
2195 		return 0;
2196 
2197 	ret = get_state_private(&BTRFS_I(inode)->io_failure_tree, start,
2198 				&private_failure);
2199 	if (ret)
2200 		return 0;
2201 
2202 	failrec = (struct io_failure_record *)(unsigned long) private_failure;
2203 	BUG_ON(!failrec->this_mirror);
2204 
2205 	if (failrec->in_validation) {
2206 		/* there was no real error, just free the record */
2207 		pr_debug("clean_io_failure: freeing dummy error at %llu\n",
2208 			 failrec->start);
2209 		goto out;
2210 	}
2211 	if (fs_info->sb->s_flags & MS_RDONLY)
2212 		goto out;
2213 
2214 	spin_lock(&BTRFS_I(inode)->io_tree.lock);
2215 	state = find_first_extent_bit_state(&BTRFS_I(inode)->io_tree,
2216 					    failrec->start,
2217 					    EXTENT_LOCKED);
2218 	spin_unlock(&BTRFS_I(inode)->io_tree.lock);
2219 
2220 	if (state && state->start <= failrec->start &&
2221 	    state->end >= failrec->start + failrec->len - 1) {
2222 		num_copies = btrfs_num_copies(fs_info, failrec->logical,
2223 					      failrec->len);
2224 		if (num_copies > 1)  {
2225 			repair_io_failure(inode, start, failrec->len,
2226 					  failrec->logical, page,
2227 					  pg_offset, failrec->failed_mirror);
2228 		}
2229 	}
2230 
2231 out:
2232 	free_io_failure(inode, failrec);
2233 
2234 	return 0;
2235 }
2236 
2237 /*
2238  * Can be called when
2239  * - hold extent lock
2240  * - under ordered extent
2241  * - the inode is freeing
2242  */
2243 void btrfs_free_io_failure_record(struct inode *inode, u64 start, u64 end)
2244 {
2245 	struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2246 	struct io_failure_record *failrec;
2247 	struct extent_state *state, *next;
2248 
2249 	if (RB_EMPTY_ROOT(&failure_tree->state))
2250 		return;
2251 
2252 	spin_lock(&failure_tree->lock);
2253 	state = find_first_extent_bit_state(failure_tree, start, EXTENT_DIRTY);
2254 	while (state) {
2255 		if (state->start > end)
2256 			break;
2257 
2258 		ASSERT(state->end <= end);
2259 
2260 		next = next_state(state);
2261 
2262 		failrec = (struct io_failure_record *)(unsigned long)state->private;
2263 		free_extent_state(state);
2264 		kfree(failrec);
2265 
2266 		state = next;
2267 	}
2268 	spin_unlock(&failure_tree->lock);
2269 }
2270 
2271 int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
2272 				struct io_failure_record **failrec_ret)
2273 {
2274 	struct io_failure_record *failrec;
2275 	u64 private;
2276 	struct extent_map *em;
2277 	struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
2278 	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2279 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2280 	int ret;
2281 	u64 logical;
2282 
2283 	ret = get_state_private(failure_tree, start, &private);
2284 	if (ret) {
2285 		failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
2286 		if (!failrec)
2287 			return -ENOMEM;
2288 
2289 		failrec->start = start;
2290 		failrec->len = end - start + 1;
2291 		failrec->this_mirror = 0;
2292 		failrec->bio_flags = 0;
2293 		failrec->in_validation = 0;
2294 
2295 		read_lock(&em_tree->lock);
2296 		em = lookup_extent_mapping(em_tree, start, failrec->len);
2297 		if (!em) {
2298 			read_unlock(&em_tree->lock);
2299 			kfree(failrec);
2300 			return -EIO;
2301 		}
2302 
2303 		if (em->start > start || em->start + em->len <= start) {
2304 			free_extent_map(em);
2305 			em = NULL;
2306 		}
2307 		read_unlock(&em_tree->lock);
2308 		if (!em) {
2309 			kfree(failrec);
2310 			return -EIO;
2311 		}
2312 
2313 		logical = start - em->start;
2314 		logical = em->block_start + logical;
2315 		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
2316 			logical = em->block_start;
2317 			failrec->bio_flags = EXTENT_BIO_COMPRESSED;
2318 			extent_set_compress_type(&failrec->bio_flags,
2319 						 em->compress_type);
2320 		}
2321 
2322 		pr_debug("Get IO Failure Record: (new) logical=%llu, start=%llu, len=%llu\n",
2323 			 logical, start, failrec->len);
2324 
2325 		failrec->logical = logical;
2326 		free_extent_map(em);
2327 
2328 		/* set the bits in the private failure tree */
2329 		ret = set_extent_bits(failure_tree, start, end,
2330 					EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
2331 		if (ret >= 0)
2332 			ret = set_state_private(failure_tree, start,
2333 						(u64)(unsigned long)failrec);
2334 		/* set the bits in the inode's tree */
2335 		if (ret >= 0)
2336 			ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED,
2337 						GFP_NOFS);
2338 		if (ret < 0) {
2339 			kfree(failrec);
2340 			return ret;
2341 		}
2342 	} else {
2343 		failrec = (struct io_failure_record *)(unsigned long)private;
2344 		pr_debug("Get IO Failure Record: (found) logical=%llu, start=%llu, len=%llu, validation=%d\n",
2345 			 failrec->logical, failrec->start, failrec->len,
2346 			 failrec->in_validation);
2347 		/*
2348 		 * when data can be on disk more than twice, add to failrec here
2349 		 * (e.g. with a list for failed_mirror) to make
2350 		 * clean_io_failure() clean all those errors at once.
2351 		 */
2352 	}
2353 
2354 	*failrec_ret = failrec;
2355 
2356 	return 0;
2357 }
2358 
2359 int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
2360 			   struct io_failure_record *failrec, int failed_mirror)
2361 {
2362 	int num_copies;
2363 
2364 	num_copies = btrfs_num_copies(BTRFS_I(inode)->root->fs_info,
2365 				      failrec->logical, failrec->len);
2366 	if (num_copies == 1) {
2367 		/*
2368 		 * we only have a single copy of the data, so don't bother with
2369 		 * all the retry and error correction code that follows. no
2370 		 * matter what the error is, it is very likely to persist.
2371 		 */
2372 		pr_debug("Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d\n",
2373 			 num_copies, failrec->this_mirror, failed_mirror);
2374 		return 0;
2375 	}
2376 
2377 	/*
2378 	 * there are two premises:
2379 	 *	a) deliver good data to the caller
2380 	 *	b) correct the bad sectors on disk
2381 	 */
2382 	if (failed_bio->bi_vcnt > 1) {
2383 		/*
2384 		 * to fulfill b), we need to know the exact failing sectors, as
2385 		 * we don't want to rewrite any more than the failed ones. thus,
2386 		 * we need separate read requests for the failed bio
2387 		 *
2388 		 * if the following BUG_ON triggers, our validation request got
2389 		 * merged. we need separate requests for our algorithm to work.
2390 		 */
2391 		BUG_ON(failrec->in_validation);
2392 		failrec->in_validation = 1;
2393 		failrec->this_mirror = failed_mirror;
2394 	} else {
2395 		/*
2396 		 * we're ready to fulfill a) and b) alongside. get a good copy
2397 		 * of the failed sector and if we succeed, we have setup
2398 		 * everything for repair_io_failure to do the rest for us.
2399 		 */
2400 		if (failrec->in_validation) {
2401 			BUG_ON(failrec->this_mirror != failed_mirror);
2402 			failrec->in_validation = 0;
2403 			failrec->this_mirror = 0;
2404 		}
2405 		failrec->failed_mirror = failed_mirror;
2406 		failrec->this_mirror++;
2407 		if (failrec->this_mirror == failed_mirror)
2408 			failrec->this_mirror++;
2409 	}
2410 
2411 	if (failrec->this_mirror > num_copies) {
2412 		pr_debug("Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d\n",
2413 			 num_copies, failrec->this_mirror, failed_mirror);
2414 		return 0;
2415 	}
2416 
2417 	return 1;
2418 }
2419 
2420 
2421 struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
2422 				    struct io_failure_record *failrec,
2423 				    struct page *page, int pg_offset, int icsum,
2424 				    bio_end_io_t *endio_func, void *data)
2425 {
2426 	struct bio *bio;
2427 	struct btrfs_io_bio *btrfs_failed_bio;
2428 	struct btrfs_io_bio *btrfs_bio;
2429 
2430 	bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
2431 	if (!bio)
2432 		return NULL;
2433 
2434 	bio->bi_end_io = endio_func;
2435 	bio->bi_iter.bi_sector = failrec->logical >> 9;
2436 	bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
2437 	bio->bi_iter.bi_size = 0;
2438 	bio->bi_private = data;
2439 
2440 	btrfs_failed_bio = btrfs_io_bio(failed_bio);
2441 	if (btrfs_failed_bio->csum) {
2442 		struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
2443 		u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
2444 
2445 		btrfs_bio = btrfs_io_bio(bio);
2446 		btrfs_bio->csum = btrfs_bio->csum_inline;
2447 		icsum *= csum_size;
2448 		memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + icsum,
2449 		       csum_size);
2450 	}
2451 
2452 	bio_add_page(bio, page, failrec->len, pg_offset);
2453 
2454 	return bio;
2455 }
2456 
2457 /*
2458  * this is a generic handler for readpage errors (default
2459  * readpage_io_failed_hook). if other copies exist, read those and write back
2460  * good data to the failed position. does not investigate in remapping the
2461  * failed extent elsewhere, hoping the device will be smart enough to do this as
2462  * needed
2463  */
2464 
2465 static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
2466 			      struct page *page, u64 start, u64 end,
2467 			      int failed_mirror)
2468 {
2469 	struct io_failure_record *failrec;
2470 	struct inode *inode = page->mapping->host;
2471 	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
2472 	struct bio *bio;
2473 	int read_mode;
2474 	int ret;
2475 
2476 	BUG_ON(failed_bio->bi_rw & REQ_WRITE);
2477 
2478 	ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
2479 	if (ret)
2480 		return ret;
2481 
2482 	ret = btrfs_check_repairable(inode, failed_bio, failrec, failed_mirror);
2483 	if (!ret) {
2484 		free_io_failure(inode, failrec);
2485 		return -EIO;
2486 	}
2487 
2488 	if (failed_bio->bi_vcnt > 1)
2489 		read_mode = READ_SYNC | REQ_FAILFAST_DEV;
2490 	else
2491 		read_mode = READ_SYNC;
2492 
2493 	phy_offset >>= inode->i_sb->s_blocksize_bits;
2494 	bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
2495 				      start - page_offset(page),
2496 				      (int)phy_offset, failed_bio->bi_end_io,
2497 				      NULL);
2498 	if (!bio) {
2499 		free_io_failure(inode, failrec);
2500 		return -EIO;
2501 	}
2502 
2503 	pr_debug("Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d\n",
2504 		 read_mode, failrec->this_mirror, failrec->in_validation);
2505 
2506 	ret = tree->ops->submit_bio_hook(inode, read_mode, bio,
2507 					 failrec->this_mirror,
2508 					 failrec->bio_flags, 0);
2509 	if (ret) {
2510 		free_io_failure(inode, failrec);
2511 		bio_put(bio);
2512 	}
2513 
2514 	return ret;
2515 }
2516 
2517 /* lots and lots of room for performance fixes in the end_bio funcs */
2518 
2519 int end_extent_writepage(struct page *page, int err, u64 start, u64 end)
2520 {
2521 	int uptodate = (err == 0);
2522 	struct extent_io_tree *tree;
2523 	int ret = 0;
2524 
2525 	tree = &BTRFS_I(page->mapping->host)->io_tree;
2526 
2527 	if (tree->ops && tree->ops->writepage_end_io_hook) {
2528 		ret = tree->ops->writepage_end_io_hook(page, start,
2529 					       end, NULL, uptodate);
2530 		if (ret)
2531 			uptodate = 0;
2532 	}
2533 
2534 	if (!uptodate) {
2535 		ClearPageUptodate(page);
2536 		SetPageError(page);
2537 		ret = ret < 0 ? ret : -EIO;
2538 		mapping_set_error(page->mapping, ret);
2539 	}
2540 	return 0;
2541 }
2542 
2543 /*
2544  * after a writepage IO is done, we need to:
2545  * clear the uptodate bits on error
2546  * clear the writeback bits in the extent tree for this IO
2547  * end_page_writeback if the page has no more pending IO
2548  *
2549  * Scheduling is not allowed, so the extent state tree is expected
2550  * to have one and only one object corresponding to this IO.
2551  */
2552 static void end_bio_extent_writepage(struct bio *bio)
2553 {
2554 	struct bio_vec *bvec;
2555 	u64 start;
2556 	u64 end;
2557 	int i;
2558 
2559 	bio_for_each_segment_all(bvec, bio, i) {
2560 		struct page *page = bvec->bv_page;
2561 
2562 		/* We always issue full-page reads, but if some block
2563 		 * in a page fails to read, blk_update_request() will
2564 		 * advance bv_offset and adjust bv_len to compensate.
2565 		 * Print a warning for nonzero offsets, and an error
2566 		 * if they don't add up to a full page.  */
2567 		if (bvec->bv_offset || bvec->bv_len != PAGE_CACHE_SIZE) {
2568 			if (bvec->bv_offset + bvec->bv_len != PAGE_CACHE_SIZE)
2569 				btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2570 				   "partial page write in btrfs with offset %u and length %u",
2571 					bvec->bv_offset, bvec->bv_len);
2572 			else
2573 				btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2574 				   "incomplete page write in btrfs with offset %u and "
2575 				   "length %u",
2576 					bvec->bv_offset, bvec->bv_len);
2577 		}
2578 
2579 		start = page_offset(page);
2580 		end = start + bvec->bv_offset + bvec->bv_len - 1;
2581 
2582 		if (end_extent_writepage(page, bio->bi_error, start, end))
2583 			continue;
2584 
2585 		end_page_writeback(page);
2586 	}
2587 
2588 	bio_put(bio);
2589 }
2590 
2591 static void
2592 endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
2593 			      int uptodate)
2594 {
2595 	struct extent_state *cached = NULL;
2596 	u64 end = start + len - 1;
2597 
2598 	if (uptodate && tree->track_uptodate)
2599 		set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
2600 	unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
2601 }
2602 
2603 /*
2604  * after a readpage IO is done, we need to:
2605  * clear the uptodate bits on error
2606  * set the uptodate bits if things worked
2607  * set the page up to date if all extents in the tree are uptodate
2608  * clear the lock bit in the extent tree
2609  * unlock the page if there are no other extents locked for it
2610  *
2611  * Scheduling is not allowed, so the extent state tree is expected
2612  * to have one and only one object corresponding to this IO.
2613  */
2614 static void end_bio_extent_readpage(struct bio *bio)
2615 {
2616 	struct bio_vec *bvec;
2617 	int uptodate = !bio->bi_error;
2618 	struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
2619 	struct extent_io_tree *tree;
2620 	u64 offset = 0;
2621 	u64 start;
2622 	u64 end;
2623 	u64 len;
2624 	u64 extent_start = 0;
2625 	u64 extent_len = 0;
2626 	int mirror;
2627 	int ret;
2628 	int i;
2629 
2630 	bio_for_each_segment_all(bvec, bio, i) {
2631 		struct page *page = bvec->bv_page;
2632 		struct inode *inode = page->mapping->host;
2633 
2634 		pr_debug("end_bio_extent_readpage: bi_sector=%llu, err=%d, "
2635 			 "mirror=%u\n", (u64)bio->bi_iter.bi_sector,
2636 			 bio->bi_error, io_bio->mirror_num);
2637 		tree = &BTRFS_I(inode)->io_tree;
2638 
2639 		/* We always issue full-page reads, but if some block
2640 		 * in a page fails to read, blk_update_request() will
2641 		 * advance bv_offset and adjust bv_len to compensate.
2642 		 * Print a warning for nonzero offsets, and an error
2643 		 * if they don't add up to a full page.  */
2644 		if (bvec->bv_offset || bvec->bv_len != PAGE_CACHE_SIZE) {
2645 			if (bvec->bv_offset + bvec->bv_len != PAGE_CACHE_SIZE)
2646 				btrfs_err(BTRFS_I(page->mapping->host)->root->fs_info,
2647 				   "partial page read in btrfs with offset %u and length %u",
2648 					bvec->bv_offset, bvec->bv_len);
2649 			else
2650 				btrfs_info(BTRFS_I(page->mapping->host)->root->fs_info,
2651 				   "incomplete page read in btrfs with offset %u and "
2652 				   "length %u",
2653 					bvec->bv_offset, bvec->bv_len);
2654 		}
2655 
2656 		start = page_offset(page);
2657 		end = start + bvec->bv_offset + bvec->bv_len - 1;
2658 		len = bvec->bv_len;
2659 
2660 		mirror = io_bio->mirror_num;
2661 		if (likely(uptodate && tree->ops &&
2662 			   tree->ops->readpage_end_io_hook)) {
2663 			ret = tree->ops->readpage_end_io_hook(io_bio, offset,
2664 							      page, start, end,
2665 							      mirror);
2666 			if (ret)
2667 				uptodate = 0;
2668 			else
2669 				clean_io_failure(inode, start, page, 0);
2670 		}
2671 
2672 		if (likely(uptodate))
2673 			goto readpage_ok;
2674 
2675 		if (tree->ops && tree->ops->readpage_io_failed_hook) {
2676 			ret = tree->ops->readpage_io_failed_hook(page, mirror);
2677 			if (!ret && !bio->bi_error)
2678 				uptodate = 1;
2679 		} else {
2680 			/*
2681 			 * The generic bio_readpage_error handles errors the
2682 			 * following way: If possible, new read requests are
2683 			 * created and submitted and will end up in
2684 			 * end_bio_extent_readpage as well (if we're lucky, not
2685 			 * in the !uptodate case). In that case it returns 0 and
2686 			 * we just go on with the next page in our bio. If it
2687 			 * can't handle the error it will return -EIO and we
2688 			 * remain responsible for that page.
2689 			 */
2690 			ret = bio_readpage_error(bio, offset, page, start, end,
2691 						 mirror);
2692 			if (ret == 0) {
2693 				uptodate = !bio->bi_error;
2694 				offset += len;
2695 				continue;
2696 			}
2697 		}
2698 readpage_ok:
2699 		if (likely(uptodate)) {
2700 			loff_t i_size = i_size_read(inode);
2701 			pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2702 			unsigned off;
2703 
2704 			/* Zero out the end if this page straddles i_size */
2705 			off = i_size & (PAGE_CACHE_SIZE-1);
2706 			if (page->index == end_index && off)
2707 				zero_user_segment(page, off, PAGE_CACHE_SIZE);
2708 			SetPageUptodate(page);
2709 		} else {
2710 			ClearPageUptodate(page);
2711 			SetPageError(page);
2712 		}
2713 		unlock_page(page);
2714 		offset += len;
2715 
2716 		if (unlikely(!uptodate)) {
2717 			if (extent_len) {
2718 				endio_readpage_release_extent(tree,
2719 							      extent_start,
2720 							      extent_len, 1);
2721 				extent_start = 0;
2722 				extent_len = 0;
2723 			}
2724 			endio_readpage_release_extent(tree, start,
2725 						      end - start + 1, 0);
2726 		} else if (!extent_len) {
2727 			extent_start = start;
2728 			extent_len = end + 1 - start;
2729 		} else if (extent_start + extent_len == start) {
2730 			extent_len += end + 1 - start;
2731 		} else {
2732 			endio_readpage_release_extent(tree, extent_start,
2733 						      extent_len, uptodate);
2734 			extent_start = start;
2735 			extent_len = end + 1 - start;
2736 		}
2737 	}
2738 
2739 	if (extent_len)
2740 		endio_readpage_release_extent(tree, extent_start, extent_len,
2741 					      uptodate);
2742 	if (io_bio->end_io)
2743 		io_bio->end_io(io_bio, bio->bi_error);
2744 	bio_put(bio);
2745 }
2746 
2747 /*
2748  * this allocates from the btrfs_bioset.  We're returning a bio right now
2749  * but you can call btrfs_io_bio for the appropriate container_of magic
2750  */
2751 struct bio *
2752 btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
2753 		gfp_t gfp_flags)
2754 {
2755 	struct btrfs_io_bio *btrfs_bio;
2756 	struct bio *bio;
2757 
2758 	bio = bio_alloc_bioset(gfp_flags, nr_vecs, btrfs_bioset);
2759 
2760 	if (bio == NULL && (current->flags & PF_MEMALLOC)) {
2761 		while (!bio && (nr_vecs /= 2)) {
2762 			bio = bio_alloc_bioset(gfp_flags,
2763 					       nr_vecs, btrfs_bioset);
2764 		}
2765 	}
2766 
2767 	if (bio) {
2768 		bio->bi_bdev = bdev;
2769 		bio->bi_iter.bi_sector = first_sector;
2770 		btrfs_bio = btrfs_io_bio(bio);
2771 		btrfs_bio->csum = NULL;
2772 		btrfs_bio->csum_allocated = NULL;
2773 		btrfs_bio->end_io = NULL;
2774 	}
2775 	return bio;
2776 }
2777 
2778 struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
2779 {
2780 	struct btrfs_io_bio *btrfs_bio;
2781 	struct bio *new;
2782 
2783 	new = bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
2784 	if (new) {
2785 		btrfs_bio = btrfs_io_bio(new);
2786 		btrfs_bio->csum = NULL;
2787 		btrfs_bio->csum_allocated = NULL;
2788 		btrfs_bio->end_io = NULL;
2789 
2790 #ifdef CONFIG_BLK_CGROUP
2791 		/* FIXME, put this into bio_clone_bioset */
2792 		if (bio->bi_css)
2793 			bio_associate_blkcg(new, bio->bi_css);
2794 #endif
2795 	}
2796 	return new;
2797 }
2798 
2799 /* this also allocates from the btrfs_bioset */
2800 struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
2801 {
2802 	struct btrfs_io_bio *btrfs_bio;
2803 	struct bio *bio;
2804 
2805 	bio = bio_alloc_bioset(gfp_mask, nr_iovecs, btrfs_bioset);
2806 	if (bio) {
2807 		btrfs_bio = btrfs_io_bio(bio);
2808 		btrfs_bio->csum = NULL;
2809 		btrfs_bio->csum_allocated = NULL;
2810 		btrfs_bio->end_io = NULL;
2811 	}
2812 	return bio;
2813 }
2814 
2815 
2816 static int __must_check submit_one_bio(int rw, struct bio *bio,
2817 				       int mirror_num, unsigned long bio_flags)
2818 {
2819 	int ret = 0;
2820 	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
2821 	struct page *page = bvec->bv_page;
2822 	struct extent_io_tree *tree = bio->bi_private;
2823 	u64 start;
2824 
2825 	start = page_offset(page) + bvec->bv_offset;
2826 
2827 	bio->bi_private = NULL;
2828 
2829 	bio_get(bio);
2830 
2831 	if (tree->ops && tree->ops->submit_bio_hook)
2832 		ret = tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
2833 					   mirror_num, bio_flags, start);
2834 	else
2835 		btrfsic_submit_bio(rw, bio);
2836 
2837 	bio_put(bio);
2838 	return ret;
2839 }
2840 
2841 static int merge_bio(int rw, struct extent_io_tree *tree, struct page *page,
2842 		     unsigned long offset, size_t size, struct bio *bio,
2843 		     unsigned long bio_flags)
2844 {
2845 	int ret = 0;
2846 	if (tree->ops && tree->ops->merge_bio_hook)
2847 		ret = tree->ops->merge_bio_hook(rw, page, offset, size, bio,
2848 						bio_flags);
2849 	BUG_ON(ret < 0);
2850 	return ret;
2851 
2852 }
2853 
2854 static int submit_extent_page(int rw, struct extent_io_tree *tree,
2855 			      struct writeback_control *wbc,
2856 			      struct page *page, sector_t sector,
2857 			      size_t size, unsigned long offset,
2858 			      struct block_device *bdev,
2859 			      struct bio **bio_ret,
2860 			      unsigned long max_pages,
2861 			      bio_end_io_t end_io_func,
2862 			      int mirror_num,
2863 			      unsigned long prev_bio_flags,
2864 			      unsigned long bio_flags,
2865 			      bool force_bio_submit)
2866 {
2867 	int ret = 0;
2868 	struct bio *bio;
2869 	int contig = 0;
2870 	int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED;
2871 	size_t page_size = min_t(size_t, size, PAGE_CACHE_SIZE);
2872 
2873 	if (bio_ret && *bio_ret) {
2874 		bio = *bio_ret;
2875 		if (old_compressed)
2876 			contig = bio->bi_iter.bi_sector == sector;
2877 		else
2878 			contig = bio_end_sector(bio) == sector;
2879 
2880 		if (prev_bio_flags != bio_flags || !contig ||
2881 		    force_bio_submit ||
2882 		    merge_bio(rw, tree, page, offset, page_size, bio, bio_flags) ||
2883 		    bio_add_page(bio, page, page_size, offset) < page_size) {
2884 			ret = submit_one_bio(rw, bio, mirror_num,
2885 					     prev_bio_flags);
2886 			if (ret < 0) {
2887 				*bio_ret = NULL;
2888 				return ret;
2889 			}
2890 			bio = NULL;
2891 		} else {
2892 			if (wbc)
2893 				wbc_account_io(wbc, page, page_size);
2894 			return 0;
2895 		}
2896 	}
2897 
2898 	bio = btrfs_bio_alloc(bdev, sector, BIO_MAX_PAGES,
2899 			GFP_NOFS | __GFP_HIGH);
2900 	if (!bio)
2901 		return -ENOMEM;
2902 
2903 	bio_add_page(bio, page, page_size, offset);
2904 	bio->bi_end_io = end_io_func;
2905 	bio->bi_private = tree;
2906 	if (wbc) {
2907 		wbc_init_bio(wbc, bio);
2908 		wbc_account_io(wbc, page, page_size);
2909 	}
2910 
2911 	if (bio_ret)
2912 		*bio_ret = bio;
2913 	else
2914 		ret = submit_one_bio(rw, bio, mirror_num, bio_flags);
2915 
2916 	return ret;
2917 }
2918 
2919 static void attach_extent_buffer_page(struct extent_buffer *eb,
2920 				      struct page *page)
2921 {
2922 	if (!PagePrivate(page)) {
2923 		SetPagePrivate(page);
2924 		page_cache_get(page);
2925 		set_page_private(page, (unsigned long)eb);
2926 	} else {
2927 		WARN_ON(page->private != (unsigned long)eb);
2928 	}
2929 }
2930 
2931 void set_page_extent_mapped(struct page *page)
2932 {
2933 	if (!PagePrivate(page)) {
2934 		SetPagePrivate(page);
2935 		page_cache_get(page);
2936 		set_page_private(page, EXTENT_PAGE_PRIVATE);
2937 	}
2938 }
2939 
2940 static struct extent_map *
2941 __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
2942 		 u64 start, u64 len, get_extent_t *get_extent,
2943 		 struct extent_map **em_cached)
2944 {
2945 	struct extent_map *em;
2946 
2947 	if (em_cached && *em_cached) {
2948 		em = *em_cached;
2949 		if (extent_map_in_tree(em) && start >= em->start &&
2950 		    start < extent_map_end(em)) {
2951 			atomic_inc(&em->refs);
2952 			return em;
2953 		}
2954 
2955 		free_extent_map(em);
2956 		*em_cached = NULL;
2957 	}
2958 
2959 	em = get_extent(inode, page, pg_offset, start, len, 0);
2960 	if (em_cached && !IS_ERR_OR_NULL(em)) {
2961 		BUG_ON(*em_cached);
2962 		atomic_inc(&em->refs);
2963 		*em_cached = em;
2964 	}
2965 	return em;
2966 }
2967 /*
2968  * basic readpage implementation.  Locked extent state structs are inserted
2969  * into the tree that are removed when the IO is done (by the end_io
2970  * handlers)
2971  * XXX JDM: This needs looking at to ensure proper page locking
2972  */
2973 static int __do_readpage(struct extent_io_tree *tree,
2974 			 struct page *page,
2975 			 get_extent_t *get_extent,
2976 			 struct extent_map **em_cached,
2977 			 struct bio **bio, int mirror_num,
2978 			 unsigned long *bio_flags, int rw,
2979 			 u64 *prev_em_start)
2980 {
2981 	struct inode *inode = page->mapping->host;
2982 	u64 start = page_offset(page);
2983 	u64 page_end = start + PAGE_CACHE_SIZE - 1;
2984 	u64 end;
2985 	u64 cur = start;
2986 	u64 extent_offset;
2987 	u64 last_byte = i_size_read(inode);
2988 	u64 block_start;
2989 	u64 cur_end;
2990 	sector_t sector;
2991 	struct extent_map *em;
2992 	struct block_device *bdev;
2993 	int ret;
2994 	int nr = 0;
2995 	int parent_locked = *bio_flags & EXTENT_BIO_PARENT_LOCKED;
2996 	size_t pg_offset = 0;
2997 	size_t iosize;
2998 	size_t disk_io_size;
2999 	size_t blocksize = inode->i_sb->s_blocksize;
3000 	unsigned long this_bio_flag = *bio_flags & EXTENT_BIO_PARENT_LOCKED;
3001 
3002 	set_page_extent_mapped(page);
3003 
3004 	end = page_end;
3005 	if (!PageUptodate(page)) {
3006 		if (cleancache_get_page(page) == 0) {
3007 			BUG_ON(blocksize != PAGE_SIZE);
3008 			unlock_extent(tree, start, end);
3009 			goto out;
3010 		}
3011 	}
3012 
3013 	if (page->index == last_byte >> PAGE_CACHE_SHIFT) {
3014 		char *userpage;
3015 		size_t zero_offset = last_byte & (PAGE_CACHE_SIZE - 1);
3016 
3017 		if (zero_offset) {
3018 			iosize = PAGE_CACHE_SIZE - zero_offset;
3019 			userpage = kmap_atomic(page);
3020 			memset(userpage + zero_offset, 0, iosize);
3021 			flush_dcache_page(page);
3022 			kunmap_atomic(userpage);
3023 		}
3024 	}
3025 	while (cur <= end) {
3026 		unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
3027 		bool force_bio_submit = false;
3028 
3029 		if (cur >= last_byte) {
3030 			char *userpage;
3031 			struct extent_state *cached = NULL;
3032 
3033 			iosize = PAGE_CACHE_SIZE - pg_offset;
3034 			userpage = kmap_atomic(page);
3035 			memset(userpage + pg_offset, 0, iosize);
3036 			flush_dcache_page(page);
3037 			kunmap_atomic(userpage);
3038 			set_extent_uptodate(tree, cur, cur + iosize - 1,
3039 					    &cached, GFP_NOFS);
3040 			if (!parent_locked)
3041 				unlock_extent_cached(tree, cur,
3042 						     cur + iosize - 1,
3043 						     &cached, GFP_NOFS);
3044 			break;
3045 		}
3046 		em = __get_extent_map(inode, page, pg_offset, cur,
3047 				      end - cur + 1, get_extent, em_cached);
3048 		if (IS_ERR_OR_NULL(em)) {
3049 			SetPageError(page);
3050 			if (!parent_locked)
3051 				unlock_extent(tree, cur, end);
3052 			break;
3053 		}
3054 		extent_offset = cur - em->start;
3055 		BUG_ON(extent_map_end(em) <= cur);
3056 		BUG_ON(end < cur);
3057 
3058 		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
3059 			this_bio_flag |= EXTENT_BIO_COMPRESSED;
3060 			extent_set_compress_type(&this_bio_flag,
3061 						 em->compress_type);
3062 		}
3063 
3064 		iosize = min(extent_map_end(em) - cur, end - cur + 1);
3065 		cur_end = min(extent_map_end(em) - 1, end);
3066 		iosize = ALIGN(iosize, blocksize);
3067 		if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
3068 			disk_io_size = em->block_len;
3069 			sector = em->block_start >> 9;
3070 		} else {
3071 			sector = (em->block_start + extent_offset) >> 9;
3072 			disk_io_size = iosize;
3073 		}
3074 		bdev = em->bdev;
3075 		block_start = em->block_start;
3076 		if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
3077 			block_start = EXTENT_MAP_HOLE;
3078 
3079 		/*
3080 		 * If we have a file range that points to a compressed extent
3081 		 * and it's followed by a consecutive file range that points to
3082 		 * to the same compressed extent (possibly with a different
3083 		 * offset and/or length, so it either points to the whole extent
3084 		 * or only part of it), we must make sure we do not submit a
3085 		 * single bio to populate the pages for the 2 ranges because
3086 		 * this makes the compressed extent read zero out the pages
3087 		 * belonging to the 2nd range. Imagine the following scenario:
3088 		 *
3089 		 *  File layout
3090 		 *  [0 - 8K]                     [8K - 24K]
3091 		 *    |                               |
3092 		 *    |                               |
3093 		 * points to extent X,         points to extent X,
3094 		 * offset 4K, length of 8K     offset 0, length 16K
3095 		 *
3096 		 * [extent X, compressed length = 4K uncompressed length = 16K]
3097 		 *
3098 		 * If the bio to read the compressed extent covers both ranges,
3099 		 * it will decompress extent X into the pages belonging to the
3100 		 * first range and then it will stop, zeroing out the remaining
3101 		 * pages that belong to the other range that points to extent X.
3102 		 * So here we make sure we submit 2 bios, one for the first
3103 		 * range and another one for the third range. Both will target
3104 		 * the same physical extent from disk, but we can't currently
3105 		 * make the compressed bio endio callback populate the pages
3106 		 * for both ranges because each compressed bio is tightly
3107 		 * coupled with a single extent map, and each range can have
3108 		 * an extent map with a different offset value relative to the
3109 		 * uncompressed data of our extent and different lengths. This
3110 		 * is a corner case so we prioritize correctness over
3111 		 * non-optimal behavior (submitting 2 bios for the same extent).
3112 		 */
3113 		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) &&
3114 		    prev_em_start && *prev_em_start != (u64)-1 &&
3115 		    *prev_em_start != em->orig_start)
3116 			force_bio_submit = true;
3117 
3118 		if (prev_em_start)
3119 			*prev_em_start = em->orig_start;
3120 
3121 		free_extent_map(em);
3122 		em = NULL;
3123 
3124 		/* we've found a hole, just zero and go on */
3125 		if (block_start == EXTENT_MAP_HOLE) {
3126 			char *userpage;
3127 			struct extent_state *cached = NULL;
3128 
3129 			userpage = kmap_atomic(page);
3130 			memset(userpage + pg_offset, 0, iosize);
3131 			flush_dcache_page(page);
3132 			kunmap_atomic(userpage);
3133 
3134 			set_extent_uptodate(tree, cur, cur + iosize - 1,
3135 					    &cached, GFP_NOFS);
3136 			if (parent_locked)
3137 				free_extent_state(cached);
3138 			else
3139 				unlock_extent_cached(tree, cur,
3140 						     cur + iosize - 1,
3141 						     &cached, GFP_NOFS);
3142 			cur = cur + iosize;
3143 			pg_offset += iosize;
3144 			continue;
3145 		}
3146 		/* the get_extent function already copied into the page */
3147 		if (test_range_bit(tree, cur, cur_end,
3148 				   EXTENT_UPTODATE, 1, NULL)) {
3149 			check_page_uptodate(tree, page);
3150 			if (!parent_locked)
3151 				unlock_extent(tree, cur, cur + iosize - 1);
3152 			cur = cur + iosize;
3153 			pg_offset += iosize;
3154 			continue;
3155 		}
3156 		/* we have an inline extent but it didn't get marked up
3157 		 * to date.  Error out
3158 		 */
3159 		if (block_start == EXTENT_MAP_INLINE) {
3160 			SetPageError(page);
3161 			if (!parent_locked)
3162 				unlock_extent(tree, cur, cur + iosize - 1);
3163 			cur = cur + iosize;
3164 			pg_offset += iosize;
3165 			continue;
3166 		}
3167 
3168 		pnr -= page->index;
3169 		ret = submit_extent_page(rw, tree, NULL, page,
3170 					 sector, disk_io_size, pg_offset,
3171 					 bdev, bio, pnr,
3172 					 end_bio_extent_readpage, mirror_num,
3173 					 *bio_flags,
3174 					 this_bio_flag,
3175 					 force_bio_submit);
3176 		if (!ret) {
3177 			nr++;
3178 			*bio_flags = this_bio_flag;
3179 		} else {
3180 			SetPageError(page);
3181 			if (!parent_locked)
3182 				unlock_extent(tree, cur, cur + iosize - 1);
3183 		}
3184 		cur = cur + iosize;
3185 		pg_offset += iosize;
3186 	}
3187 out:
3188 	if (!nr) {
3189 		if (!PageError(page))
3190 			SetPageUptodate(page);
3191 		unlock_page(page);
3192 	}
3193 	return 0;
3194 }
3195 
3196 static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
3197 					     struct page *pages[], int nr_pages,
3198 					     u64 start, u64 end,
3199 					     get_extent_t *get_extent,
3200 					     struct extent_map **em_cached,
3201 					     struct bio **bio, int mirror_num,
3202 					     unsigned long *bio_flags, int rw,
3203 					     u64 *prev_em_start)
3204 {
3205 	struct inode *inode;
3206 	struct btrfs_ordered_extent *ordered;
3207 	int index;
3208 
3209 	inode = pages[0]->mapping->host;
3210 	while (1) {
3211 		lock_extent(tree, start, end);
3212 		ordered = btrfs_lookup_ordered_range(inode, start,
3213 						     end - start + 1);
3214 		if (!ordered)
3215 			break;
3216 		unlock_extent(tree, start, end);
3217 		btrfs_start_ordered_extent(inode, ordered, 1);
3218 		btrfs_put_ordered_extent(ordered);
3219 	}
3220 
3221 	for (index = 0; index < nr_pages; index++) {
3222 		__do_readpage(tree, pages[index], get_extent, em_cached, bio,
3223 			      mirror_num, bio_flags, rw, prev_em_start);
3224 		page_cache_release(pages[index]);
3225 	}
3226 }
3227 
3228 static void __extent_readpages(struct extent_io_tree *tree,
3229 			       struct page *pages[],
3230 			       int nr_pages, get_extent_t *get_extent,
3231 			       struct extent_map **em_cached,
3232 			       struct bio **bio, int mirror_num,
3233 			       unsigned long *bio_flags, int rw,
3234 			       u64 *prev_em_start)
3235 {
3236 	u64 start = 0;
3237 	u64 end = 0;
3238 	u64 page_start;
3239 	int index;
3240 	int first_index = 0;
3241 
3242 	for (index = 0; index < nr_pages; index++) {
3243 		page_start = page_offset(pages[index]);
3244 		if (!end) {
3245 			start = page_start;
3246 			end = start + PAGE_CACHE_SIZE - 1;
3247 			first_index = index;
3248 		} else if (end + 1 == page_start) {
3249 			end += PAGE_CACHE_SIZE;
3250 		} else {
3251 			__do_contiguous_readpages(tree, &pages[first_index],
3252 						  index - first_index, start,
3253 						  end, get_extent, em_cached,
3254 						  bio, mirror_num, bio_flags,
3255 						  rw, prev_em_start);
3256 			start = page_start;
3257 			end = start + PAGE_CACHE_SIZE - 1;
3258 			first_index = index;
3259 		}
3260 	}
3261 
3262 	if (end)
3263 		__do_contiguous_readpages(tree, &pages[first_index],
3264 					  index - first_index, start,
3265 					  end, get_extent, em_cached, bio,
3266 					  mirror_num, bio_flags, rw,
3267 					  prev_em_start);
3268 }
3269 
3270 static int __extent_read_full_page(struct extent_io_tree *tree,
3271 				   struct page *page,
3272 				   get_extent_t *get_extent,
3273 				   struct bio **bio, int mirror_num,
3274 				   unsigned long *bio_flags, int rw)
3275 {
3276 	struct inode *inode = page->mapping->host;
3277 	struct btrfs_ordered_extent *ordered;
3278 	u64 start = page_offset(page);
3279 	u64 end = start + PAGE_CACHE_SIZE - 1;
3280 	int ret;
3281 
3282 	while (1) {
3283 		lock_extent(tree, start, end);
3284 		ordered = btrfs_lookup_ordered_extent(inode, start);
3285 		if (!ordered)
3286 			break;
3287 		unlock_extent(tree, start, end);
3288 		btrfs_start_ordered_extent(inode, ordered, 1);
3289 		btrfs_put_ordered_extent(ordered);
3290 	}
3291 
3292 	ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
3293 			    bio_flags, rw, NULL);
3294 	return ret;
3295 }
3296 
3297 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
3298 			    get_extent_t *get_extent, int mirror_num)
3299 {
3300 	struct bio *bio = NULL;
3301 	unsigned long bio_flags = 0;
3302 	int ret;
3303 
3304 	ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
3305 				      &bio_flags, READ);
3306 	if (bio)
3307 		ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
3308 	return ret;
3309 }
3310 
3311 int extent_read_full_page_nolock(struct extent_io_tree *tree, struct page *page,
3312 				 get_extent_t *get_extent, int mirror_num)
3313 {
3314 	struct bio *bio = NULL;
3315 	unsigned long bio_flags = EXTENT_BIO_PARENT_LOCKED;
3316 	int ret;
3317 
3318 	ret = __do_readpage(tree, page, get_extent, NULL, &bio, mirror_num,
3319 			    &bio_flags, READ, NULL);
3320 	if (bio)
3321 		ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
3322 	return ret;
3323 }
3324 
3325 static noinline void update_nr_written(struct page *page,
3326 				      struct writeback_control *wbc,
3327 				      unsigned long nr_written)
3328 {
3329 	wbc->nr_to_write -= nr_written;
3330 	if (wbc->range_cyclic || (wbc->nr_to_write > 0 &&
3331 	    wbc->range_start == 0 && wbc->range_end == LLONG_MAX))
3332 		page->mapping->writeback_index = page->index + nr_written;
3333 }
3334 
3335 /*
3336  * helper for __extent_writepage, doing all of the delayed allocation setup.
3337  *
3338  * This returns 1 if our fill_delalloc function did all the work required
3339  * to write the page (copy into inline extent).  In this case the IO has
3340  * been started and the page is already unlocked.
3341  *
3342  * This returns 0 if all went well (page still locked)
3343  * This returns < 0 if there were errors (page still locked)
3344  */
3345 static noinline_for_stack int writepage_delalloc(struct inode *inode,
3346 			      struct page *page, struct writeback_control *wbc,
3347 			      struct extent_page_data *epd,
3348 			      u64 delalloc_start,
3349 			      unsigned long *nr_written)
3350 {
3351 	struct extent_io_tree *tree = epd->tree;
3352 	u64 page_end = delalloc_start + PAGE_CACHE_SIZE - 1;
3353 	u64 nr_delalloc;
3354 	u64 delalloc_to_write = 0;
3355 	u64 delalloc_end = 0;
3356 	int ret;
3357 	int page_started = 0;
3358 
3359 	if (epd->extent_locked || !tree->ops || !tree->ops->fill_delalloc)
3360 		return 0;
3361 
3362 	while (delalloc_end < page_end) {
3363 		nr_delalloc = find_lock_delalloc_range(inode, tree,
3364 					       page,
3365 					       &delalloc_start,
3366 					       &delalloc_end,
3367 					       BTRFS_MAX_EXTENT_SIZE);
3368 		if (nr_delalloc == 0) {
3369 			delalloc_start = delalloc_end + 1;
3370 			continue;
3371 		}
3372 		ret = tree->ops->fill_delalloc(inode, page,
3373 					       delalloc_start,
3374 					       delalloc_end,
3375 					       &page_started,
3376 					       nr_written);
3377 		/* File system has been set read-only */
3378 		if (ret) {
3379 			SetPageError(page);
3380 			/* fill_delalloc should be return < 0 for error
3381 			 * but just in case, we use > 0 here meaning the
3382 			 * IO is started, so we don't want to return > 0
3383 			 * unless things are going well.
3384 			 */
3385 			ret = ret < 0 ? ret : -EIO;
3386 			goto done;
3387 		}
3388 		/*
3389 		 * delalloc_end is already one less than the total
3390 		 * length, so we don't subtract one from
3391 		 * PAGE_CACHE_SIZE
3392 		 */
3393 		delalloc_to_write += (delalloc_end - delalloc_start +
3394 				      PAGE_CACHE_SIZE) >>
3395 				      PAGE_CACHE_SHIFT;
3396 		delalloc_start = delalloc_end + 1;
3397 	}
3398 	if (wbc->nr_to_write < delalloc_to_write) {
3399 		int thresh = 8192;
3400 
3401 		if (delalloc_to_write < thresh * 2)
3402 			thresh = delalloc_to_write;
3403 		wbc->nr_to_write = min_t(u64, delalloc_to_write,
3404 					 thresh);
3405 	}
3406 
3407 	/* did the fill delalloc function already unlock and start
3408 	 * the IO?
3409 	 */
3410 	if (page_started) {
3411 		/*
3412 		 * we've unlocked the page, so we can't update
3413 		 * the mapping's writeback index, just update
3414 		 * nr_to_write.
3415 		 */
3416 		wbc->nr_to_write -= *nr_written;
3417 		return 1;
3418 	}
3419 
3420 	ret = 0;
3421 
3422 done:
3423 	return ret;
3424 }
3425 
3426 /*
3427  * helper for __extent_writepage.  This calls the writepage start hooks,
3428  * and does the loop to map the page into extents and bios.
3429  *
3430  * We return 1 if the IO is started and the page is unlocked,
3431  * 0 if all went well (page still locked)
3432  * < 0 if there were errors (page still locked)
3433  */
3434 static noinline_for_stack int __extent_writepage_io(struct inode *inode,
3435 				 struct page *page,
3436 				 struct writeback_control *wbc,
3437 				 struct extent_page_data *epd,
3438 				 loff_t i_size,
3439 				 unsigned long nr_written,
3440 				 int write_flags, int *nr_ret)
3441 {
3442 	struct extent_io_tree *tree = epd->tree;
3443 	u64 start = page_offset(page);
3444 	u64 page_end = start + PAGE_CACHE_SIZE - 1;
3445 	u64 end;
3446 	u64 cur = start;
3447 	u64 extent_offset;
3448 	u64 block_start;
3449 	u64 iosize;
3450 	sector_t sector;
3451 	struct extent_state *cached_state = NULL;
3452 	struct extent_map *em;
3453 	struct block_device *bdev;
3454 	size_t pg_offset = 0;
3455 	size_t blocksize;
3456 	int ret = 0;
3457 	int nr = 0;
3458 	bool compressed;
3459 
3460 	if (tree->ops && tree->ops->writepage_start_hook) {
3461 		ret = tree->ops->writepage_start_hook(page, start,
3462 						      page_end);
3463 		if (ret) {
3464 			/* Fixup worker will requeue */
3465 			if (ret == -EBUSY)
3466 				wbc->pages_skipped++;
3467 			else
3468 				redirty_page_for_writepage(wbc, page);
3469 
3470 			update_nr_written(page, wbc, nr_written);
3471 			unlock_page(page);
3472 			ret = 1;
3473 			goto done_unlocked;
3474 		}
3475 	}
3476 
3477 	/*
3478 	 * we don't want to touch the inode after unlocking the page,
3479 	 * so we update the mapping writeback index now
3480 	 */
3481 	update_nr_written(page, wbc, nr_written + 1);
3482 
3483 	end = page_end;
3484 	if (i_size <= start) {
3485 		if (tree->ops && tree->ops->writepage_end_io_hook)
3486 			tree->ops->writepage_end_io_hook(page, start,
3487 							 page_end, NULL, 1);
3488 		goto done;
3489 	}
3490 
3491 	blocksize = inode->i_sb->s_blocksize;
3492 
3493 	while (cur <= end) {
3494 		u64 em_end;
3495 		if (cur >= i_size) {
3496 			if (tree->ops && tree->ops->writepage_end_io_hook)
3497 				tree->ops->writepage_end_io_hook(page, cur,
3498 							 page_end, NULL, 1);
3499 			break;
3500 		}
3501 		em = epd->get_extent(inode, page, pg_offset, cur,
3502 				     end - cur + 1, 1);
3503 		if (IS_ERR_OR_NULL(em)) {
3504 			SetPageError(page);
3505 			ret = PTR_ERR_OR_ZERO(em);
3506 			break;
3507 		}
3508 
3509 		extent_offset = cur - em->start;
3510 		em_end = extent_map_end(em);
3511 		BUG_ON(em_end <= cur);
3512 		BUG_ON(end < cur);
3513 		iosize = min(em_end - cur, end - cur + 1);
3514 		iosize = ALIGN(iosize, blocksize);
3515 		sector = (em->block_start + extent_offset) >> 9;
3516 		bdev = em->bdev;
3517 		block_start = em->block_start;
3518 		compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
3519 		free_extent_map(em);
3520 		em = NULL;
3521 
3522 		/*
3523 		 * compressed and inline extents are written through other
3524 		 * paths in the FS
3525 		 */
3526 		if (compressed || block_start == EXTENT_MAP_HOLE ||
3527 		    block_start == EXTENT_MAP_INLINE) {
3528 			/*
3529 			 * end_io notification does not happen here for
3530 			 * compressed extents
3531 			 */
3532 			if (!compressed && tree->ops &&
3533 			    tree->ops->writepage_end_io_hook)
3534 				tree->ops->writepage_end_io_hook(page, cur,
3535 							 cur + iosize - 1,
3536 							 NULL, 1);
3537 			else if (compressed) {
3538 				/* we don't want to end_page_writeback on
3539 				 * a compressed extent.  this happens
3540 				 * elsewhere
3541 				 */
3542 				nr++;
3543 			}
3544 
3545 			cur += iosize;
3546 			pg_offset += iosize;
3547 			continue;
3548 		}
3549 
3550 		if (tree->ops && tree->ops->writepage_io_hook) {
3551 			ret = tree->ops->writepage_io_hook(page, cur,
3552 						cur + iosize - 1);
3553 		} else {
3554 			ret = 0;
3555 		}
3556 		if (ret) {
3557 			SetPageError(page);
3558 		} else {
3559 			unsigned long max_nr = (i_size >> PAGE_CACHE_SHIFT) + 1;
3560 
3561 			set_range_writeback(tree, cur, cur + iosize - 1);
3562 			if (!PageWriteback(page)) {
3563 				btrfs_err(BTRFS_I(inode)->root->fs_info,
3564 					   "page %lu not writeback, cur %llu end %llu",
3565 				       page->index, cur, end);
3566 			}
3567 
3568 			ret = submit_extent_page(write_flags, tree, wbc, page,
3569 						 sector, iosize, pg_offset,
3570 						 bdev, &epd->bio, max_nr,
3571 						 end_bio_extent_writepage,
3572 						 0, 0, 0, false);
3573 			if (ret)
3574 				SetPageError(page);
3575 		}
3576 		cur = cur + iosize;
3577 		pg_offset += iosize;
3578 		nr++;
3579 	}
3580 done:
3581 	*nr_ret = nr;
3582 
3583 done_unlocked:
3584 
3585 	/* drop our reference on any cached states */
3586 	free_extent_state(cached_state);
3587 	return ret;
3588 }
3589 
3590 /*
3591  * the writepage semantics are similar to regular writepage.  extent
3592  * records are inserted to lock ranges in the tree, and as dirty areas
3593  * are found, they are marked writeback.  Then the lock bits are removed
3594  * and the end_io handler clears the writeback ranges
3595  */
3596 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
3597 			      void *data)
3598 {
3599 	struct inode *inode = page->mapping->host;
3600 	struct extent_page_data *epd = data;
3601 	u64 start = page_offset(page);
3602 	u64 page_end = start + PAGE_CACHE_SIZE - 1;
3603 	int ret;
3604 	int nr = 0;
3605 	size_t pg_offset = 0;
3606 	loff_t i_size = i_size_read(inode);
3607 	unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
3608 	int write_flags;
3609 	unsigned long nr_written = 0;
3610 
3611 	if (wbc->sync_mode == WB_SYNC_ALL)
3612 		write_flags = WRITE_SYNC;
3613 	else
3614 		write_flags = WRITE;
3615 
3616 	trace___extent_writepage(page, inode, wbc);
3617 
3618 	WARN_ON(!PageLocked(page));
3619 
3620 	ClearPageError(page);
3621 
3622 	pg_offset = i_size & (PAGE_CACHE_SIZE - 1);
3623 	if (page->index > end_index ||
3624 	   (page->index == end_index && !pg_offset)) {
3625 		page->mapping->a_ops->invalidatepage(page, 0, PAGE_CACHE_SIZE);
3626 		unlock_page(page);
3627 		return 0;
3628 	}
3629 
3630 	if (page->index == end_index) {
3631 		char *userpage;
3632 
3633 		userpage = kmap_atomic(page);
3634 		memset(userpage + pg_offset, 0,
3635 		       PAGE_CACHE_SIZE - pg_offset);
3636 		kunmap_atomic(userpage);
3637 		flush_dcache_page(page);
3638 	}
3639 
3640 	pg_offset = 0;
3641 
3642 	set_page_extent_mapped(page);
3643 
3644 	ret = writepage_delalloc(inode, page, wbc, epd, start, &nr_written);
3645 	if (ret == 1)
3646 		goto done_unlocked;
3647 	if (ret)
3648 		goto done;
3649 
3650 	ret = __extent_writepage_io(inode, page, wbc, epd,
3651 				    i_size, nr_written, write_flags, &nr);
3652 	if (ret == 1)
3653 		goto done_unlocked;
3654 
3655 done:
3656 	if (nr == 0) {
3657 		/* make sure the mapping tag for page dirty gets cleared */
3658 		set_page_writeback(page);
3659 		end_page_writeback(page);
3660 	}
3661 	if (PageError(page)) {
3662 		ret = ret < 0 ? ret : -EIO;
3663 		end_extent_writepage(page, ret, start, page_end);
3664 	}
3665 	unlock_page(page);
3666 	return ret;
3667 
3668 done_unlocked:
3669 	return 0;
3670 }
3671 
3672 void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
3673 {
3674 	wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
3675 		       TASK_UNINTERRUPTIBLE);
3676 }
3677 
3678 static noinline_for_stack int
3679 lock_extent_buffer_for_io(struct extent_buffer *eb,
3680 			  struct btrfs_fs_info *fs_info,
3681 			  struct extent_page_data *epd)
3682 {
3683 	unsigned long i, num_pages;
3684 	int flush = 0;
3685 	int ret = 0;
3686 
3687 	if (!btrfs_try_tree_write_lock(eb)) {
3688 		flush = 1;
3689 		flush_write_bio(epd);
3690 		btrfs_tree_lock(eb);
3691 	}
3692 
3693 	if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
3694 		btrfs_tree_unlock(eb);
3695 		if (!epd->sync_io)
3696 			return 0;
3697 		if (!flush) {
3698 			flush_write_bio(epd);
3699 			flush = 1;
3700 		}
3701 		while (1) {
3702 			wait_on_extent_buffer_writeback(eb);
3703 			btrfs_tree_lock(eb);
3704 			if (!test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags))
3705 				break;
3706 			btrfs_tree_unlock(eb);
3707 		}
3708 	}
3709 
3710 	/*
3711 	 * We need to do this to prevent races in people who check if the eb is
3712 	 * under IO since we can end up having no IO bits set for a short period
3713 	 * of time.
3714 	 */
3715 	spin_lock(&eb->refs_lock);
3716 	if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
3717 		set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3718 		spin_unlock(&eb->refs_lock);
3719 		btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
3720 		__percpu_counter_add(&fs_info->dirty_metadata_bytes,
3721 				     -eb->len,
3722 				     fs_info->dirty_metadata_batch);
3723 		ret = 1;
3724 	} else {
3725 		spin_unlock(&eb->refs_lock);
3726 	}
3727 
3728 	btrfs_tree_unlock(eb);
3729 
3730 	if (!ret)
3731 		return ret;
3732 
3733 	num_pages = num_extent_pages(eb->start, eb->len);
3734 	for (i = 0; i < num_pages; i++) {
3735 		struct page *p = eb->pages[i];
3736 
3737 		if (!trylock_page(p)) {
3738 			if (!flush) {
3739 				flush_write_bio(epd);
3740 				flush = 1;
3741 			}
3742 			lock_page(p);
3743 		}
3744 	}
3745 
3746 	return ret;
3747 }
3748 
3749 static void end_extent_buffer_writeback(struct extent_buffer *eb)
3750 {
3751 	clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
3752 	smp_mb__after_atomic();
3753 	wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
3754 }
3755 
3756 static void set_btree_ioerr(struct page *page)
3757 {
3758 	struct extent_buffer *eb = (struct extent_buffer *)page->private;
3759 	struct btrfs_inode *btree_ino = BTRFS_I(eb->fs_info->btree_inode);
3760 
3761 	SetPageError(page);
3762 	if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
3763 		return;
3764 
3765 	/*
3766 	 * If writeback for a btree extent that doesn't belong to a log tree
3767 	 * failed, increment the counter transaction->eb_write_errors.
3768 	 * We do this because while the transaction is running and before it's
3769 	 * committing (when we call filemap_fdata[write|wait]_range against
3770 	 * the btree inode), we might have
3771 	 * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
3772 	 * returns an error or an error happens during writeback, when we're
3773 	 * committing the transaction we wouldn't know about it, since the pages
3774 	 * can be no longer dirty nor marked anymore for writeback (if a
3775 	 * subsequent modification to the extent buffer didn't happen before the
3776 	 * transaction commit), which makes filemap_fdata[write|wait]_range not
3777 	 * able to find the pages tagged with SetPageError at transaction
3778 	 * commit time. So if this happens we must abort the transaction,
3779 	 * otherwise we commit a super block with btree roots that point to
3780 	 * btree nodes/leafs whose content on disk is invalid - either garbage
3781 	 * or the content of some node/leaf from a past generation that got
3782 	 * cowed or deleted and is no longer valid.
3783 	 *
3784 	 * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
3785 	 * not be enough - we need to distinguish between log tree extents vs
3786 	 * non-log tree extents, and the next filemap_fdatawait_range() call
3787 	 * will catch and clear such errors in the mapping - and that call might
3788 	 * be from a log sync and not from a transaction commit. Also, checking
3789 	 * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
3790 	 * not done and would not be reliable - the eb might have been released
3791 	 * from memory and reading it back again means that flag would not be
3792 	 * set (since it's a runtime flag, not persisted on disk).
3793 	 *
3794 	 * Using the flags below in the btree inode also makes us achieve the
3795 	 * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
3796 	 * writeback for all dirty pages and before filemap_fdatawait_range()
3797 	 * is called, the writeback for all dirty pages had already finished
3798 	 * with errors - because we were not using AS_EIO/AS_ENOSPC,
3799 	 * filemap_fdatawait_range() would return success, as it could not know
3800 	 * that writeback errors happened (the pages were no longer tagged for
3801 	 * writeback).
3802 	 */
3803 	switch (eb->log_index) {
3804 	case -1:
3805 		set_bit(BTRFS_INODE_BTREE_ERR, &btree_ino->runtime_flags);
3806 		break;
3807 	case 0:
3808 		set_bit(BTRFS_INODE_BTREE_LOG1_ERR, &btree_ino->runtime_flags);
3809 		break;
3810 	case 1:
3811 		set_bit(BTRFS_INODE_BTREE_LOG2_ERR, &btree_ino->runtime_flags);
3812 		break;
3813 	default:
3814 		BUG(); /* unexpected, logic error */
3815 	}
3816 }
3817 
3818 static void end_bio_extent_buffer_writepage(struct bio *bio)
3819 {
3820 	struct bio_vec *bvec;
3821 	struct extent_buffer *eb;
3822 	int i, done;
3823 
3824 	bio_for_each_segment_all(bvec, bio, i) {
3825 		struct page *page = bvec->bv_page;
3826 
3827 		eb = (struct extent_buffer *)page->private;
3828 		BUG_ON(!eb);
3829 		done = atomic_dec_and_test(&eb->io_pages);
3830 
3831 		if (bio->bi_error ||
3832 		    test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
3833 			ClearPageUptodate(page);
3834 			set_btree_ioerr(page);
3835 		}
3836 
3837 		end_page_writeback(page);
3838 
3839 		if (!done)
3840 			continue;
3841 
3842 		end_extent_buffer_writeback(eb);
3843 	}
3844 
3845 	bio_put(bio);
3846 }
3847 
3848 static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
3849 			struct btrfs_fs_info *fs_info,
3850 			struct writeback_control *wbc,
3851 			struct extent_page_data *epd)
3852 {
3853 	struct block_device *bdev = fs_info->fs_devices->latest_bdev;
3854 	struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
3855 	u64 offset = eb->start;
3856 	unsigned long i, num_pages;
3857 	unsigned long bio_flags = 0;
3858 	int rw = (epd->sync_io ? WRITE_SYNC : WRITE) | REQ_META;
3859 	int ret = 0;
3860 
3861 	clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
3862 	num_pages = num_extent_pages(eb->start, eb->len);
3863 	atomic_set(&eb->io_pages, num_pages);
3864 	if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
3865 		bio_flags = EXTENT_BIO_TREE_LOG;
3866 
3867 	for (i = 0; i < num_pages; i++) {
3868 		struct page *p = eb->pages[i];
3869 
3870 		clear_page_dirty_for_io(p);
3871 		set_page_writeback(p);
3872 		ret = submit_extent_page(rw, tree, wbc, p, offset >> 9,
3873 					 PAGE_CACHE_SIZE, 0, bdev, &epd->bio,
3874 					 -1, end_bio_extent_buffer_writepage,
3875 					 0, epd->bio_flags, bio_flags, false);
3876 		epd->bio_flags = bio_flags;
3877 		if (ret) {
3878 			set_btree_ioerr(p);
3879 			end_page_writeback(p);
3880 			if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
3881 				end_extent_buffer_writeback(eb);
3882 			ret = -EIO;
3883 			break;
3884 		}
3885 		offset += PAGE_CACHE_SIZE;
3886 		update_nr_written(p, wbc, 1);
3887 		unlock_page(p);
3888 	}
3889 
3890 	if (unlikely(ret)) {
3891 		for (; i < num_pages; i++) {
3892 			struct page *p = eb->pages[i];
3893 			clear_page_dirty_for_io(p);
3894 			unlock_page(p);
3895 		}
3896 	}
3897 
3898 	return ret;
3899 }
3900 
3901 int btree_write_cache_pages(struct address_space *mapping,
3902 				   struct writeback_control *wbc)
3903 {
3904 	struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
3905 	struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
3906 	struct extent_buffer *eb, *prev_eb = NULL;
3907 	struct extent_page_data epd = {
3908 		.bio = NULL,
3909 		.tree = tree,
3910 		.extent_locked = 0,
3911 		.sync_io = wbc->sync_mode == WB_SYNC_ALL,
3912 		.bio_flags = 0,
3913 	};
3914 	int ret = 0;
3915 	int done = 0;
3916 	int nr_to_write_done = 0;
3917 	struct pagevec pvec;
3918 	int nr_pages;
3919 	pgoff_t index;
3920 	pgoff_t end;		/* Inclusive */
3921 	int scanned = 0;
3922 	int tag;
3923 
3924 	pagevec_init(&pvec, 0);
3925 	if (wbc->range_cyclic) {
3926 		index = mapping->writeback_index; /* Start from prev offset */
3927 		end = -1;
3928 	} else {
3929 		index = wbc->range_start >> PAGE_CACHE_SHIFT;
3930 		end = wbc->range_end >> PAGE_CACHE_SHIFT;
3931 		scanned = 1;
3932 	}
3933 	if (wbc->sync_mode == WB_SYNC_ALL)
3934 		tag = PAGECACHE_TAG_TOWRITE;
3935 	else
3936 		tag = PAGECACHE_TAG_DIRTY;
3937 retry:
3938 	if (wbc->sync_mode == WB_SYNC_ALL)
3939 		tag_pages_for_writeback(mapping, index, end);
3940 	while (!done && !nr_to_write_done && (index <= end) &&
3941 	       (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
3942 			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
3943 		unsigned i;
3944 
3945 		scanned = 1;
3946 		for (i = 0; i < nr_pages; i++) {
3947 			struct page *page = pvec.pages[i];
3948 
3949 			if (!PagePrivate(page))
3950 				continue;
3951 
3952 			if (!wbc->range_cyclic && page->index > end) {
3953 				done = 1;
3954 				break;
3955 			}
3956 
3957 			spin_lock(&mapping->private_lock);
3958 			if (!PagePrivate(page)) {
3959 				spin_unlock(&mapping->private_lock);
3960 				continue;
3961 			}
3962 
3963 			eb = (struct extent_buffer *)page->private;
3964 
3965 			/*
3966 			 * Shouldn't happen and normally this would be a BUG_ON
3967 			 * but no sense in crashing the users box for something
3968 			 * we can survive anyway.
3969 			 */
3970 			if (WARN_ON(!eb)) {
3971 				spin_unlock(&mapping->private_lock);
3972 				continue;
3973 			}
3974 
3975 			if (eb == prev_eb) {
3976 				spin_unlock(&mapping->private_lock);
3977 				continue;
3978 			}
3979 
3980 			ret = atomic_inc_not_zero(&eb->refs);
3981 			spin_unlock(&mapping->private_lock);
3982 			if (!ret)
3983 				continue;
3984 
3985 			prev_eb = eb;
3986 			ret = lock_extent_buffer_for_io(eb, fs_info, &epd);
3987 			if (!ret) {
3988 				free_extent_buffer(eb);
3989 				continue;
3990 			}
3991 
3992 			ret = write_one_eb(eb, fs_info, wbc, &epd);
3993 			if (ret) {
3994 				done = 1;
3995 				free_extent_buffer(eb);
3996 				break;
3997 			}
3998 			free_extent_buffer(eb);
3999 
4000 			/*
4001 			 * the filesystem may choose to bump up nr_to_write.
4002 			 * We have to make sure to honor the new nr_to_write
4003 			 * at any time
4004 			 */
4005 			nr_to_write_done = wbc->nr_to_write <= 0;
4006 		}
4007 		pagevec_release(&pvec);
4008 		cond_resched();
4009 	}
4010 	if (!scanned && !done) {
4011 		/*
4012 		 * We hit the last page and there is more work to be done: wrap
4013 		 * back to the start of the file
4014 		 */
4015 		scanned = 1;
4016 		index = 0;
4017 		goto retry;
4018 	}
4019 	flush_write_bio(&epd);
4020 	return ret;
4021 }
4022 
4023 /**
4024  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
4025  * @mapping: address space structure to write
4026  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
4027  * @writepage: function called for each page
4028  * @data: data passed to writepage function
4029  *
4030  * If a page is already under I/O, write_cache_pages() skips it, even
4031  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
4032  * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
4033  * and msync() need to guarantee that all the data which was dirty at the time
4034  * the call was made get new I/O started against them.  If wbc->sync_mode is
4035  * WB_SYNC_ALL then we were called for data integrity and we must wait for
4036  * existing IO to complete.
4037  */
4038 static int extent_write_cache_pages(struct extent_io_tree *tree,
4039 			     struct address_space *mapping,
4040 			     struct writeback_control *wbc,
4041 			     writepage_t writepage, void *data,
4042 			     void (*flush_fn)(void *))
4043 {
4044 	struct inode *inode = mapping->host;
4045 	int ret = 0;
4046 	int done = 0;
4047 	int err = 0;
4048 	int nr_to_write_done = 0;
4049 	struct pagevec pvec;
4050 	int nr_pages;
4051 	pgoff_t index;
4052 	pgoff_t end;		/* Inclusive */
4053 	int scanned = 0;
4054 	int tag;
4055 
4056 	/*
4057 	 * We have to hold onto the inode so that ordered extents can do their
4058 	 * work when the IO finishes.  The alternative to this is failing to add
4059 	 * an ordered extent if the igrab() fails there and that is a huge pain
4060 	 * to deal with, so instead just hold onto the inode throughout the
4061 	 * writepages operation.  If it fails here we are freeing up the inode
4062 	 * anyway and we'd rather not waste our time writing out stuff that is
4063 	 * going to be truncated anyway.
4064 	 */
4065 	if (!igrab(inode))
4066 		return 0;
4067 
4068 	pagevec_init(&pvec, 0);
4069 	if (wbc->range_cyclic) {
4070 		index = mapping->writeback_index; /* Start from prev offset */
4071 		end = -1;
4072 	} else {
4073 		index = wbc->range_start >> PAGE_CACHE_SHIFT;
4074 		end = wbc->range_end >> PAGE_CACHE_SHIFT;
4075 		scanned = 1;
4076 	}
4077 	if (wbc->sync_mode == WB_SYNC_ALL)
4078 		tag = PAGECACHE_TAG_TOWRITE;
4079 	else
4080 		tag = PAGECACHE_TAG_DIRTY;
4081 retry:
4082 	if (wbc->sync_mode == WB_SYNC_ALL)
4083 		tag_pages_for_writeback(mapping, index, end);
4084 	while (!done && !nr_to_write_done && (index <= end) &&
4085 	       (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
4086 			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
4087 		unsigned i;
4088 
4089 		scanned = 1;
4090 		for (i = 0; i < nr_pages; i++) {
4091 			struct page *page = pvec.pages[i];
4092 
4093 			/*
4094 			 * At this point we hold neither mapping->tree_lock nor
4095 			 * lock on the page itself: the page may be truncated or
4096 			 * invalidated (changing page->mapping to NULL), or even
4097 			 * swizzled back from swapper_space to tmpfs file
4098 			 * mapping
4099 			 */
4100 			if (!trylock_page(page)) {
4101 				flush_fn(data);
4102 				lock_page(page);
4103 			}
4104 
4105 			if (unlikely(page->mapping != mapping)) {
4106 				unlock_page(page);
4107 				continue;
4108 			}
4109 
4110 			if (!wbc->range_cyclic && page->index > end) {
4111 				done = 1;
4112 				unlock_page(page);
4113 				continue;
4114 			}
4115 
4116 			if (wbc->sync_mode != WB_SYNC_NONE) {
4117 				if (PageWriteback(page))
4118 					flush_fn(data);
4119 				wait_on_page_writeback(page);
4120 			}
4121 
4122 			if (PageWriteback(page) ||
4123 			    !clear_page_dirty_for_io(page)) {
4124 				unlock_page(page);
4125 				continue;
4126 			}
4127 
4128 			ret = (*writepage)(page, wbc, data);
4129 
4130 			if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
4131 				unlock_page(page);
4132 				ret = 0;
4133 			}
4134 			if (!err && ret < 0)
4135 				err = ret;
4136 
4137 			/*
4138 			 * the filesystem may choose to bump up nr_to_write.
4139 			 * We have to make sure to honor the new nr_to_write
4140 			 * at any time
4141 			 */
4142 			nr_to_write_done = wbc->nr_to_write <= 0;
4143 		}
4144 		pagevec_release(&pvec);
4145 		cond_resched();
4146 	}
4147 	if (!scanned && !done && !err) {
4148 		/*
4149 		 * We hit the last page and there is more work to be done: wrap
4150 		 * back to the start of the file
4151 		 */
4152 		scanned = 1;
4153 		index = 0;
4154 		goto retry;
4155 	}
4156 	btrfs_add_delayed_iput(inode);
4157 	return err;
4158 }
4159 
4160 static void flush_epd_write_bio(struct extent_page_data *epd)
4161 {
4162 	if (epd->bio) {
4163 		int rw = WRITE;
4164 		int ret;
4165 
4166 		if (epd->sync_io)
4167 			rw = WRITE_SYNC;
4168 
4169 		ret = submit_one_bio(rw, epd->bio, 0, epd->bio_flags);
4170 		BUG_ON(ret < 0); /* -ENOMEM */
4171 		epd->bio = NULL;
4172 	}
4173 }
4174 
4175 static noinline void flush_write_bio(void *data)
4176 {
4177 	struct extent_page_data *epd = data;
4178 	flush_epd_write_bio(epd);
4179 }
4180 
4181 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
4182 			  get_extent_t *get_extent,
4183 			  struct writeback_control *wbc)
4184 {
4185 	int ret;
4186 	struct extent_page_data epd = {
4187 		.bio = NULL,
4188 		.tree = tree,
4189 		.get_extent = get_extent,
4190 		.extent_locked = 0,
4191 		.sync_io = wbc->sync_mode == WB_SYNC_ALL,
4192 		.bio_flags = 0,
4193 	};
4194 
4195 	ret = __extent_writepage(page, wbc, &epd);
4196 
4197 	flush_epd_write_bio(&epd);
4198 	return ret;
4199 }
4200 
4201 int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
4202 			      u64 start, u64 end, get_extent_t *get_extent,
4203 			      int mode)
4204 {
4205 	int ret = 0;
4206 	struct address_space *mapping = inode->i_mapping;
4207 	struct page *page;
4208 	unsigned long nr_pages = (end - start + PAGE_CACHE_SIZE) >>
4209 		PAGE_CACHE_SHIFT;
4210 
4211 	struct extent_page_data epd = {
4212 		.bio = NULL,
4213 		.tree = tree,
4214 		.get_extent = get_extent,
4215 		.extent_locked = 1,
4216 		.sync_io = mode == WB_SYNC_ALL,
4217 		.bio_flags = 0,
4218 	};
4219 	struct writeback_control wbc_writepages = {
4220 		.sync_mode	= mode,
4221 		.nr_to_write	= nr_pages * 2,
4222 		.range_start	= start,
4223 		.range_end	= end + 1,
4224 	};
4225 
4226 	while (start <= end) {
4227 		page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
4228 		if (clear_page_dirty_for_io(page))
4229 			ret = __extent_writepage(page, &wbc_writepages, &epd);
4230 		else {
4231 			if (tree->ops && tree->ops->writepage_end_io_hook)
4232 				tree->ops->writepage_end_io_hook(page, start,
4233 						 start + PAGE_CACHE_SIZE - 1,
4234 						 NULL, 1);
4235 			unlock_page(page);
4236 		}
4237 		page_cache_release(page);
4238 		start += PAGE_CACHE_SIZE;
4239 	}
4240 
4241 	flush_epd_write_bio(&epd);
4242 	return ret;
4243 }
4244 
4245 int extent_writepages(struct extent_io_tree *tree,
4246 		      struct address_space *mapping,
4247 		      get_extent_t *get_extent,
4248 		      struct writeback_control *wbc)
4249 {
4250 	int ret = 0;
4251 	struct extent_page_data epd = {
4252 		.bio = NULL,
4253 		.tree = tree,
4254 		.get_extent = get_extent,
4255 		.extent_locked = 0,
4256 		.sync_io = wbc->sync_mode == WB_SYNC_ALL,
4257 		.bio_flags = 0,
4258 	};
4259 
4260 	ret = extent_write_cache_pages(tree, mapping, wbc,
4261 				       __extent_writepage, &epd,
4262 				       flush_write_bio);
4263 	flush_epd_write_bio(&epd);
4264 	return ret;
4265 }
4266 
4267 int extent_readpages(struct extent_io_tree *tree,
4268 		     struct address_space *mapping,
4269 		     struct list_head *pages, unsigned nr_pages,
4270 		     get_extent_t get_extent)
4271 {
4272 	struct bio *bio = NULL;
4273 	unsigned page_idx;
4274 	unsigned long bio_flags = 0;
4275 	struct page *pagepool[16];
4276 	struct page *page;
4277 	struct extent_map *em_cached = NULL;
4278 	int nr = 0;
4279 	u64 prev_em_start = (u64)-1;
4280 
4281 	for (page_idx = 0; page_idx < nr_pages; page_idx++) {
4282 		page = list_entry(pages->prev, struct page, lru);
4283 
4284 		prefetchw(&page->flags);
4285 		list_del(&page->lru);
4286 		if (add_to_page_cache_lru(page, mapping,
4287 					page->index, GFP_NOFS)) {
4288 			page_cache_release(page);
4289 			continue;
4290 		}
4291 
4292 		pagepool[nr++] = page;
4293 		if (nr < ARRAY_SIZE(pagepool))
4294 			continue;
4295 		__extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4296 				   &bio, 0, &bio_flags, READ, &prev_em_start);
4297 		nr = 0;
4298 	}
4299 	if (nr)
4300 		__extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
4301 				   &bio, 0, &bio_flags, READ, &prev_em_start);
4302 
4303 	if (em_cached)
4304 		free_extent_map(em_cached);
4305 
4306 	BUG_ON(!list_empty(pages));
4307 	if (bio)
4308 		return submit_one_bio(READ, bio, 0, bio_flags);
4309 	return 0;
4310 }
4311 
4312 /*
4313  * basic invalidatepage code, this waits on any locked or writeback
4314  * ranges corresponding to the page, and then deletes any extent state
4315  * records from the tree
4316  */
4317 int extent_invalidatepage(struct extent_io_tree *tree,
4318 			  struct page *page, unsigned long offset)
4319 {
4320 	struct extent_state *cached_state = NULL;
4321 	u64 start = page_offset(page);
4322 	u64 end = start + PAGE_CACHE_SIZE - 1;
4323 	size_t blocksize = page->mapping->host->i_sb->s_blocksize;
4324 
4325 	start += ALIGN(offset, blocksize);
4326 	if (start > end)
4327 		return 0;
4328 
4329 	lock_extent_bits(tree, start, end, 0, &cached_state);
4330 	wait_on_page_writeback(page);
4331 	clear_extent_bit(tree, start, end,
4332 			 EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
4333 			 EXTENT_DO_ACCOUNTING,
4334 			 1, 1, &cached_state, GFP_NOFS);
4335 	return 0;
4336 }
4337 
4338 /*
4339  * a helper for releasepage, this tests for areas of the page that
4340  * are locked or under IO and drops the related state bits if it is safe
4341  * to drop the page.
4342  */
4343 static int try_release_extent_state(struct extent_map_tree *map,
4344 				    struct extent_io_tree *tree,
4345 				    struct page *page, gfp_t mask)
4346 {
4347 	u64 start = page_offset(page);
4348 	u64 end = start + PAGE_CACHE_SIZE - 1;
4349 	int ret = 1;
4350 
4351 	if (test_range_bit(tree, start, end,
4352 			   EXTENT_IOBITS, 0, NULL))
4353 		ret = 0;
4354 	else {
4355 		if ((mask & GFP_NOFS) == GFP_NOFS)
4356 			mask = GFP_NOFS;
4357 		/*
4358 		 * at this point we can safely clear everything except the
4359 		 * locked bit and the nodatasum bit
4360 		 */
4361 		ret = clear_extent_bit(tree, start, end,
4362 				 ~(EXTENT_LOCKED | EXTENT_NODATASUM),
4363 				 0, 0, NULL, mask);
4364 
4365 		/* if clear_extent_bit failed for enomem reasons,
4366 		 * we can't allow the release to continue.
4367 		 */
4368 		if (ret < 0)
4369 			ret = 0;
4370 		else
4371 			ret = 1;
4372 	}
4373 	return ret;
4374 }
4375 
4376 /*
4377  * a helper for releasepage.  As long as there are no locked extents
4378  * in the range corresponding to the page, both state records and extent
4379  * map records are removed
4380  */
4381 int try_release_extent_mapping(struct extent_map_tree *map,
4382 			       struct extent_io_tree *tree, struct page *page,
4383 			       gfp_t mask)
4384 {
4385 	struct extent_map *em;
4386 	u64 start = page_offset(page);
4387 	u64 end = start + PAGE_CACHE_SIZE - 1;
4388 
4389 	if (gfpflags_allow_blocking(mask) &&
4390 	    page->mapping->host->i_size > 16 * 1024 * 1024) {
4391 		u64 len;
4392 		while (start <= end) {
4393 			len = end - start + 1;
4394 			write_lock(&map->lock);
4395 			em = lookup_extent_mapping(map, start, len);
4396 			if (!em) {
4397 				write_unlock(&map->lock);
4398 				break;
4399 			}
4400 			if (test_bit(EXTENT_FLAG_PINNED, &em->flags) ||
4401 			    em->start != start) {
4402 				write_unlock(&map->lock);
4403 				free_extent_map(em);
4404 				break;
4405 			}
4406 			if (!test_range_bit(tree, em->start,
4407 					    extent_map_end(em) - 1,
4408 					    EXTENT_LOCKED | EXTENT_WRITEBACK,
4409 					    0, NULL)) {
4410 				remove_extent_mapping(map, em);
4411 				/* once for the rb tree */
4412 				free_extent_map(em);
4413 			}
4414 			start = extent_map_end(em);
4415 			write_unlock(&map->lock);
4416 
4417 			/* once for us */
4418 			free_extent_map(em);
4419 		}
4420 	}
4421 	return try_release_extent_state(map, tree, page, mask);
4422 }
4423 
4424 /*
4425  * helper function for fiemap, which doesn't want to see any holes.
4426  * This maps until we find something past 'last'
4427  */
4428 static struct extent_map *get_extent_skip_holes(struct inode *inode,
4429 						u64 offset,
4430 						u64 last,
4431 						get_extent_t *get_extent)
4432 {
4433 	u64 sectorsize = BTRFS_I(inode)->root->sectorsize;
4434 	struct extent_map *em;
4435 	u64 len;
4436 
4437 	if (offset >= last)
4438 		return NULL;
4439 
4440 	while (1) {
4441 		len = last - offset;
4442 		if (len == 0)
4443 			break;
4444 		len = ALIGN(len, sectorsize);
4445 		em = get_extent(inode, NULL, 0, offset, len, 0);
4446 		if (IS_ERR_OR_NULL(em))
4447 			return em;
4448 
4449 		/* if this isn't a hole return it */
4450 		if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
4451 		    em->block_start != EXTENT_MAP_HOLE) {
4452 			return em;
4453 		}
4454 
4455 		/* this is a hole, advance to the next extent */
4456 		offset = extent_map_end(em);
4457 		free_extent_map(em);
4458 		if (offset >= last)
4459 			break;
4460 	}
4461 	return NULL;
4462 }
4463 
4464 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
4465 		__u64 start, __u64 len, get_extent_t *get_extent)
4466 {
4467 	int ret = 0;
4468 	u64 off = start;
4469 	u64 max = start + len;
4470 	u32 flags = 0;
4471 	u32 found_type;
4472 	u64 last;
4473 	u64 last_for_get_extent = 0;
4474 	u64 disko = 0;
4475 	u64 isize = i_size_read(inode);
4476 	struct btrfs_key found_key;
4477 	struct extent_map *em = NULL;
4478 	struct extent_state *cached_state = NULL;
4479 	struct btrfs_path *path;
4480 	struct btrfs_root *root = BTRFS_I(inode)->root;
4481 	int end = 0;
4482 	u64 em_start = 0;
4483 	u64 em_len = 0;
4484 	u64 em_end = 0;
4485 
4486 	if (len == 0)
4487 		return -EINVAL;
4488 
4489 	path = btrfs_alloc_path();
4490 	if (!path)
4491 		return -ENOMEM;
4492 	path->leave_spinning = 1;
4493 
4494 	start = round_down(start, BTRFS_I(inode)->root->sectorsize);
4495 	len = round_up(max, BTRFS_I(inode)->root->sectorsize) - start;
4496 
4497 	/*
4498 	 * lookup the last file extent.  We're not using i_size here
4499 	 * because there might be preallocation past i_size
4500 	 */
4501 	ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode), -1,
4502 				       0);
4503 	if (ret < 0) {
4504 		btrfs_free_path(path);
4505 		return ret;
4506 	}
4507 	WARN_ON(!ret);
4508 	path->slots[0]--;
4509 	btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
4510 	found_type = found_key.type;
4511 
4512 	/* No extents, but there might be delalloc bits */
4513 	if (found_key.objectid != btrfs_ino(inode) ||
4514 	    found_type != BTRFS_EXTENT_DATA_KEY) {
4515 		/* have to trust i_size as the end */
4516 		last = (u64)-1;
4517 		last_for_get_extent = isize;
4518 	} else {
4519 		/*
4520 		 * remember the start of the last extent.  There are a
4521 		 * bunch of different factors that go into the length of the
4522 		 * extent, so its much less complex to remember where it started
4523 		 */
4524 		last = found_key.offset;
4525 		last_for_get_extent = last + 1;
4526 	}
4527 	btrfs_release_path(path);
4528 
4529 	/*
4530 	 * we might have some extents allocated but more delalloc past those
4531 	 * extents.  so, we trust isize unless the start of the last extent is
4532 	 * beyond isize
4533 	 */
4534 	if (last < isize) {
4535 		last = (u64)-1;
4536 		last_for_get_extent = isize;
4537 	}
4538 
4539 	lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len - 1, 0,
4540 			 &cached_state);
4541 
4542 	em = get_extent_skip_holes(inode, start, last_for_get_extent,
4543 				   get_extent);
4544 	if (!em)
4545 		goto out;
4546 	if (IS_ERR(em)) {
4547 		ret = PTR_ERR(em);
4548 		goto out;
4549 	}
4550 
4551 	while (!end) {
4552 		u64 offset_in_extent = 0;
4553 
4554 		/* break if the extent we found is outside the range */
4555 		if (em->start >= max || extent_map_end(em) < off)
4556 			break;
4557 
4558 		/*
4559 		 * get_extent may return an extent that starts before our
4560 		 * requested range.  We have to make sure the ranges
4561 		 * we return to fiemap always move forward and don't
4562 		 * overlap, so adjust the offsets here
4563 		 */
4564 		em_start = max(em->start, off);
4565 
4566 		/*
4567 		 * record the offset from the start of the extent
4568 		 * for adjusting the disk offset below.  Only do this if the
4569 		 * extent isn't compressed since our in ram offset may be past
4570 		 * what we have actually allocated on disk.
4571 		 */
4572 		if (!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4573 			offset_in_extent = em_start - em->start;
4574 		em_end = extent_map_end(em);
4575 		em_len = em_end - em_start;
4576 		disko = 0;
4577 		flags = 0;
4578 
4579 		/*
4580 		 * bump off for our next call to get_extent
4581 		 */
4582 		off = extent_map_end(em);
4583 		if (off >= max)
4584 			end = 1;
4585 
4586 		if (em->block_start == EXTENT_MAP_LAST_BYTE) {
4587 			end = 1;
4588 			flags |= FIEMAP_EXTENT_LAST;
4589 		} else if (em->block_start == EXTENT_MAP_INLINE) {
4590 			flags |= (FIEMAP_EXTENT_DATA_INLINE |
4591 				  FIEMAP_EXTENT_NOT_ALIGNED);
4592 		} else if (em->block_start == EXTENT_MAP_DELALLOC) {
4593 			flags |= (FIEMAP_EXTENT_DELALLOC |
4594 				  FIEMAP_EXTENT_UNKNOWN);
4595 		} else if (fieinfo->fi_extents_max) {
4596 			u64 bytenr = em->block_start -
4597 				(em->start - em->orig_start);
4598 
4599 			disko = em->block_start + offset_in_extent;
4600 
4601 			/*
4602 			 * As btrfs supports shared space, this information
4603 			 * can be exported to userspace tools via
4604 			 * flag FIEMAP_EXTENT_SHARED.  If fi_extents_max == 0
4605 			 * then we're just getting a count and we can skip the
4606 			 * lookup stuff.
4607 			 */
4608 			ret = btrfs_check_shared(NULL, root->fs_info,
4609 						 root->objectid,
4610 						 btrfs_ino(inode), bytenr);
4611 			if (ret < 0)
4612 				goto out_free;
4613 			if (ret)
4614 				flags |= FIEMAP_EXTENT_SHARED;
4615 			ret = 0;
4616 		}
4617 		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
4618 			flags |= FIEMAP_EXTENT_ENCODED;
4619 		if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
4620 			flags |= FIEMAP_EXTENT_UNWRITTEN;
4621 
4622 		free_extent_map(em);
4623 		em = NULL;
4624 		if ((em_start >= last) || em_len == (u64)-1 ||
4625 		   (last == (u64)-1 && isize <= em_end)) {
4626 			flags |= FIEMAP_EXTENT_LAST;
4627 			end = 1;
4628 		}
4629 
4630 		/* now scan forward to see if this is really the last extent. */
4631 		em = get_extent_skip_holes(inode, off, last_for_get_extent,
4632 					   get_extent);
4633 		if (IS_ERR(em)) {
4634 			ret = PTR_ERR(em);
4635 			goto out;
4636 		}
4637 		if (!em) {
4638 			flags |= FIEMAP_EXTENT_LAST;
4639 			end = 1;
4640 		}
4641 		ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
4642 					      em_len, flags);
4643 		if (ret) {
4644 			if (ret == 1)
4645 				ret = 0;
4646 			goto out_free;
4647 		}
4648 	}
4649 out_free:
4650 	free_extent_map(em);
4651 out:
4652 	btrfs_free_path(path);
4653 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
4654 			     &cached_state, GFP_NOFS);
4655 	return ret;
4656 }
4657 
4658 static void __free_extent_buffer(struct extent_buffer *eb)
4659 {
4660 	btrfs_leak_debug_del(&eb->leak_list);
4661 	kmem_cache_free(extent_buffer_cache, eb);
4662 }
4663 
4664 int extent_buffer_under_io(struct extent_buffer *eb)
4665 {
4666 	return (atomic_read(&eb->io_pages) ||
4667 		test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
4668 		test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4669 }
4670 
4671 /*
4672  * Helper for releasing extent buffer page.
4673  */
4674 static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
4675 {
4676 	unsigned long index;
4677 	struct page *page;
4678 	int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4679 
4680 	BUG_ON(extent_buffer_under_io(eb));
4681 
4682 	index = num_extent_pages(eb->start, eb->len);
4683 	if (index == 0)
4684 		return;
4685 
4686 	do {
4687 		index--;
4688 		page = eb->pages[index];
4689 		if (!page)
4690 			continue;
4691 		if (mapped)
4692 			spin_lock(&page->mapping->private_lock);
4693 		/*
4694 		 * We do this since we'll remove the pages after we've
4695 		 * removed the eb from the radix tree, so we could race
4696 		 * and have this page now attached to the new eb.  So
4697 		 * only clear page_private if it's still connected to
4698 		 * this eb.
4699 		 */
4700 		if (PagePrivate(page) &&
4701 		    page->private == (unsigned long)eb) {
4702 			BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
4703 			BUG_ON(PageDirty(page));
4704 			BUG_ON(PageWriteback(page));
4705 			/*
4706 			 * We need to make sure we haven't be attached
4707 			 * to a new eb.
4708 			 */
4709 			ClearPagePrivate(page);
4710 			set_page_private(page, 0);
4711 			/* One for the page private */
4712 			page_cache_release(page);
4713 		}
4714 
4715 		if (mapped)
4716 			spin_unlock(&page->mapping->private_lock);
4717 
4718 		/* One for when we alloced the page */
4719 		page_cache_release(page);
4720 	} while (index != 0);
4721 }
4722 
4723 /*
4724  * Helper for releasing the extent buffer.
4725  */
4726 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
4727 {
4728 	btrfs_release_extent_buffer_page(eb);
4729 	__free_extent_buffer(eb);
4730 }
4731 
4732 static struct extent_buffer *
4733 __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
4734 		      unsigned long len)
4735 {
4736 	struct extent_buffer *eb = NULL;
4737 
4738 	eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
4739 	eb->start = start;
4740 	eb->len = len;
4741 	eb->fs_info = fs_info;
4742 	eb->bflags = 0;
4743 	rwlock_init(&eb->lock);
4744 	atomic_set(&eb->write_locks, 0);
4745 	atomic_set(&eb->read_locks, 0);
4746 	atomic_set(&eb->blocking_readers, 0);
4747 	atomic_set(&eb->blocking_writers, 0);
4748 	atomic_set(&eb->spinning_readers, 0);
4749 	atomic_set(&eb->spinning_writers, 0);
4750 	eb->lock_nested = 0;
4751 	init_waitqueue_head(&eb->write_lock_wq);
4752 	init_waitqueue_head(&eb->read_lock_wq);
4753 
4754 	btrfs_leak_debug_add(&eb->leak_list, &buffers);
4755 
4756 	spin_lock_init(&eb->refs_lock);
4757 	atomic_set(&eb->refs, 1);
4758 	atomic_set(&eb->io_pages, 0);
4759 
4760 	/*
4761 	 * Sanity checks, currently the maximum is 64k covered by 16x 4k pages
4762 	 */
4763 	BUILD_BUG_ON(BTRFS_MAX_METADATA_BLOCKSIZE
4764 		> MAX_INLINE_EXTENT_BUFFER_SIZE);
4765 	BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
4766 
4767 	return eb;
4768 }
4769 
4770 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
4771 {
4772 	unsigned long i;
4773 	struct page *p;
4774 	struct extent_buffer *new;
4775 	unsigned long num_pages = num_extent_pages(src->start, src->len);
4776 
4777 	new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
4778 	if (new == NULL)
4779 		return NULL;
4780 
4781 	for (i = 0; i < num_pages; i++) {
4782 		p = alloc_page(GFP_NOFS);
4783 		if (!p) {
4784 			btrfs_release_extent_buffer(new);
4785 			return NULL;
4786 		}
4787 		attach_extent_buffer_page(new, p);
4788 		WARN_ON(PageDirty(p));
4789 		SetPageUptodate(p);
4790 		new->pages[i] = p;
4791 	}
4792 
4793 	copy_extent_buffer(new, src, 0, 0, src->len);
4794 	set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
4795 	set_bit(EXTENT_BUFFER_DUMMY, &new->bflags);
4796 
4797 	return new;
4798 }
4799 
4800 struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
4801 						u64 start)
4802 {
4803 	struct extent_buffer *eb;
4804 	unsigned long len;
4805 	unsigned long num_pages;
4806 	unsigned long i;
4807 
4808 	if (!fs_info) {
4809 		/*
4810 		 * Called only from tests that don't always have a fs_info
4811 		 * available, but we know that nodesize is 4096
4812 		 */
4813 		len = 4096;
4814 	} else {
4815 		len = fs_info->tree_root->nodesize;
4816 	}
4817 	num_pages = num_extent_pages(0, len);
4818 
4819 	eb = __alloc_extent_buffer(fs_info, start, len);
4820 	if (!eb)
4821 		return NULL;
4822 
4823 	for (i = 0; i < num_pages; i++) {
4824 		eb->pages[i] = alloc_page(GFP_NOFS);
4825 		if (!eb->pages[i])
4826 			goto err;
4827 	}
4828 	set_extent_buffer_uptodate(eb);
4829 	btrfs_set_header_nritems(eb, 0);
4830 	set_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
4831 
4832 	return eb;
4833 err:
4834 	for (; i > 0; i--)
4835 		__free_page(eb->pages[i - 1]);
4836 	__free_extent_buffer(eb);
4837 	return NULL;
4838 }
4839 
4840 static void check_buffer_tree_ref(struct extent_buffer *eb)
4841 {
4842 	int refs;
4843 	/* the ref bit is tricky.  We have to make sure it is set
4844 	 * if we have the buffer dirty.   Otherwise the
4845 	 * code to free a buffer can end up dropping a dirty
4846 	 * page
4847 	 *
4848 	 * Once the ref bit is set, it won't go away while the
4849 	 * buffer is dirty or in writeback, and it also won't
4850 	 * go away while we have the reference count on the
4851 	 * eb bumped.
4852 	 *
4853 	 * We can't just set the ref bit without bumping the
4854 	 * ref on the eb because free_extent_buffer might
4855 	 * see the ref bit and try to clear it.  If this happens
4856 	 * free_extent_buffer might end up dropping our original
4857 	 * ref by mistake and freeing the page before we are able
4858 	 * to add one more ref.
4859 	 *
4860 	 * So bump the ref count first, then set the bit.  If someone
4861 	 * beat us to it, drop the ref we added.
4862 	 */
4863 	refs = atomic_read(&eb->refs);
4864 	if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4865 		return;
4866 
4867 	spin_lock(&eb->refs_lock);
4868 	if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
4869 		atomic_inc(&eb->refs);
4870 	spin_unlock(&eb->refs_lock);
4871 }
4872 
4873 static void mark_extent_buffer_accessed(struct extent_buffer *eb,
4874 		struct page *accessed)
4875 {
4876 	unsigned long num_pages, i;
4877 
4878 	check_buffer_tree_ref(eb);
4879 
4880 	num_pages = num_extent_pages(eb->start, eb->len);
4881 	for (i = 0; i < num_pages; i++) {
4882 		struct page *p = eb->pages[i];
4883 
4884 		if (p != accessed)
4885 			mark_page_accessed(p);
4886 	}
4887 }
4888 
4889 struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
4890 					 u64 start)
4891 {
4892 	struct extent_buffer *eb;
4893 
4894 	rcu_read_lock();
4895 	eb = radix_tree_lookup(&fs_info->buffer_radix,
4896 			       start >> PAGE_CACHE_SHIFT);
4897 	if (eb && atomic_inc_not_zero(&eb->refs)) {
4898 		rcu_read_unlock();
4899 		/*
4900 		 * Lock our eb's refs_lock to avoid races with
4901 		 * free_extent_buffer. When we get our eb it might be flagged
4902 		 * with EXTENT_BUFFER_STALE and another task running
4903 		 * free_extent_buffer might have seen that flag set,
4904 		 * eb->refs == 2, that the buffer isn't under IO (dirty and
4905 		 * writeback flags not set) and it's still in the tree (flag
4906 		 * EXTENT_BUFFER_TREE_REF set), therefore being in the process
4907 		 * of decrementing the extent buffer's reference count twice.
4908 		 * So here we could race and increment the eb's reference count,
4909 		 * clear its stale flag, mark it as dirty and drop our reference
4910 		 * before the other task finishes executing free_extent_buffer,
4911 		 * which would later result in an attempt to free an extent
4912 		 * buffer that is dirty.
4913 		 */
4914 		if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
4915 			spin_lock(&eb->refs_lock);
4916 			spin_unlock(&eb->refs_lock);
4917 		}
4918 		mark_extent_buffer_accessed(eb, NULL);
4919 		return eb;
4920 	}
4921 	rcu_read_unlock();
4922 
4923 	return NULL;
4924 }
4925 
4926 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
4927 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
4928 					       u64 start)
4929 {
4930 	struct extent_buffer *eb, *exists = NULL;
4931 	int ret;
4932 
4933 	eb = find_extent_buffer(fs_info, start);
4934 	if (eb)
4935 		return eb;
4936 	eb = alloc_dummy_extent_buffer(fs_info, start);
4937 	if (!eb)
4938 		return NULL;
4939 	eb->fs_info = fs_info;
4940 again:
4941 	ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
4942 	if (ret)
4943 		goto free_eb;
4944 	spin_lock(&fs_info->buffer_lock);
4945 	ret = radix_tree_insert(&fs_info->buffer_radix,
4946 				start >> PAGE_CACHE_SHIFT, eb);
4947 	spin_unlock(&fs_info->buffer_lock);
4948 	radix_tree_preload_end();
4949 	if (ret == -EEXIST) {
4950 		exists = find_extent_buffer(fs_info, start);
4951 		if (exists)
4952 			goto free_eb;
4953 		else
4954 			goto again;
4955 	}
4956 	check_buffer_tree_ref(eb);
4957 	set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
4958 
4959 	/*
4960 	 * We will free dummy extent buffer's if they come into
4961 	 * free_extent_buffer with a ref count of 2, but if we are using this we
4962 	 * want the buffers to stay in memory until we're done with them, so
4963 	 * bump the ref count again.
4964 	 */
4965 	atomic_inc(&eb->refs);
4966 	return eb;
4967 free_eb:
4968 	btrfs_release_extent_buffer(eb);
4969 	return exists;
4970 }
4971 #endif
4972 
4973 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
4974 					  u64 start)
4975 {
4976 	unsigned long len = fs_info->tree_root->nodesize;
4977 	unsigned long num_pages = num_extent_pages(start, len);
4978 	unsigned long i;
4979 	unsigned long index = start >> PAGE_CACHE_SHIFT;
4980 	struct extent_buffer *eb;
4981 	struct extent_buffer *exists = NULL;
4982 	struct page *p;
4983 	struct address_space *mapping = fs_info->btree_inode->i_mapping;
4984 	int uptodate = 1;
4985 	int ret;
4986 
4987 	eb = find_extent_buffer(fs_info, start);
4988 	if (eb)
4989 		return eb;
4990 
4991 	eb = __alloc_extent_buffer(fs_info, start, len);
4992 	if (!eb)
4993 		return NULL;
4994 
4995 	for (i = 0; i < num_pages; i++, index++) {
4996 		p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL);
4997 		if (!p)
4998 			goto free_eb;
4999 
5000 		spin_lock(&mapping->private_lock);
5001 		if (PagePrivate(p)) {
5002 			/*
5003 			 * We could have already allocated an eb for this page
5004 			 * and attached one so lets see if we can get a ref on
5005 			 * the existing eb, and if we can we know it's good and
5006 			 * we can just return that one, else we know we can just
5007 			 * overwrite page->private.
5008 			 */
5009 			exists = (struct extent_buffer *)p->private;
5010 			if (atomic_inc_not_zero(&exists->refs)) {
5011 				spin_unlock(&mapping->private_lock);
5012 				unlock_page(p);
5013 				page_cache_release(p);
5014 				mark_extent_buffer_accessed(exists, p);
5015 				goto free_eb;
5016 			}
5017 			exists = NULL;
5018 
5019 			/*
5020 			 * Do this so attach doesn't complain and we need to
5021 			 * drop the ref the old guy had.
5022 			 */
5023 			ClearPagePrivate(p);
5024 			WARN_ON(PageDirty(p));
5025 			page_cache_release(p);
5026 		}
5027 		attach_extent_buffer_page(eb, p);
5028 		spin_unlock(&mapping->private_lock);
5029 		WARN_ON(PageDirty(p));
5030 		eb->pages[i] = p;
5031 		if (!PageUptodate(p))
5032 			uptodate = 0;
5033 
5034 		/*
5035 		 * see below about how we avoid a nasty race with release page
5036 		 * and why we unlock later
5037 		 */
5038 	}
5039 	if (uptodate)
5040 		set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5041 again:
5042 	ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
5043 	if (ret)
5044 		goto free_eb;
5045 
5046 	spin_lock(&fs_info->buffer_lock);
5047 	ret = radix_tree_insert(&fs_info->buffer_radix,
5048 				start >> PAGE_CACHE_SHIFT, eb);
5049 	spin_unlock(&fs_info->buffer_lock);
5050 	radix_tree_preload_end();
5051 	if (ret == -EEXIST) {
5052 		exists = find_extent_buffer(fs_info, start);
5053 		if (exists)
5054 			goto free_eb;
5055 		else
5056 			goto again;
5057 	}
5058 	/* add one reference for the tree */
5059 	check_buffer_tree_ref(eb);
5060 	set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
5061 
5062 	/*
5063 	 * there is a race where release page may have
5064 	 * tried to find this extent buffer in the radix
5065 	 * but failed.  It will tell the VM it is safe to
5066 	 * reclaim the, and it will clear the page private bit.
5067 	 * We must make sure to set the page private bit properly
5068 	 * after the extent buffer is in the radix tree so
5069 	 * it doesn't get lost
5070 	 */
5071 	SetPageChecked(eb->pages[0]);
5072 	for (i = 1; i < num_pages; i++) {
5073 		p = eb->pages[i];
5074 		ClearPageChecked(p);
5075 		unlock_page(p);
5076 	}
5077 	unlock_page(eb->pages[0]);
5078 	return eb;
5079 
5080 free_eb:
5081 	WARN_ON(!atomic_dec_and_test(&eb->refs));
5082 	for (i = 0; i < num_pages; i++) {
5083 		if (eb->pages[i])
5084 			unlock_page(eb->pages[i]);
5085 	}
5086 
5087 	btrfs_release_extent_buffer(eb);
5088 	return exists;
5089 }
5090 
5091 static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
5092 {
5093 	struct extent_buffer *eb =
5094 			container_of(head, struct extent_buffer, rcu_head);
5095 
5096 	__free_extent_buffer(eb);
5097 }
5098 
5099 /* Expects to have eb->eb_lock already held */
5100 static int release_extent_buffer(struct extent_buffer *eb)
5101 {
5102 	WARN_ON(atomic_read(&eb->refs) == 0);
5103 	if (atomic_dec_and_test(&eb->refs)) {
5104 		if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) {
5105 			struct btrfs_fs_info *fs_info = eb->fs_info;
5106 
5107 			spin_unlock(&eb->refs_lock);
5108 
5109 			spin_lock(&fs_info->buffer_lock);
5110 			radix_tree_delete(&fs_info->buffer_radix,
5111 					  eb->start >> PAGE_CACHE_SHIFT);
5112 			spin_unlock(&fs_info->buffer_lock);
5113 		} else {
5114 			spin_unlock(&eb->refs_lock);
5115 		}
5116 
5117 		/* Should be safe to release our pages at this point */
5118 		btrfs_release_extent_buffer_page(eb);
5119 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
5120 		if (unlikely(test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))) {
5121 			__free_extent_buffer(eb);
5122 			return 1;
5123 		}
5124 #endif
5125 		call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
5126 		return 1;
5127 	}
5128 	spin_unlock(&eb->refs_lock);
5129 
5130 	return 0;
5131 }
5132 
5133 void free_extent_buffer(struct extent_buffer *eb)
5134 {
5135 	int refs;
5136 	int old;
5137 	if (!eb)
5138 		return;
5139 
5140 	while (1) {
5141 		refs = atomic_read(&eb->refs);
5142 		if (refs <= 3)
5143 			break;
5144 		old = atomic_cmpxchg(&eb->refs, refs, refs - 1);
5145 		if (old == refs)
5146 			return;
5147 	}
5148 
5149 	spin_lock(&eb->refs_lock);
5150 	if (atomic_read(&eb->refs) == 2 &&
5151 	    test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags))
5152 		atomic_dec(&eb->refs);
5153 
5154 	if (atomic_read(&eb->refs) == 2 &&
5155 	    test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
5156 	    !extent_buffer_under_io(eb) &&
5157 	    test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5158 		atomic_dec(&eb->refs);
5159 
5160 	/*
5161 	 * I know this is terrible, but it's temporary until we stop tracking
5162 	 * the uptodate bits and such for the extent buffers.
5163 	 */
5164 	release_extent_buffer(eb);
5165 }
5166 
5167 void free_extent_buffer_stale(struct extent_buffer *eb)
5168 {
5169 	if (!eb)
5170 		return;
5171 
5172 	spin_lock(&eb->refs_lock);
5173 	set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
5174 
5175 	if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
5176 	    test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
5177 		atomic_dec(&eb->refs);
5178 	release_extent_buffer(eb);
5179 }
5180 
5181 void clear_extent_buffer_dirty(struct extent_buffer *eb)
5182 {
5183 	unsigned long i;
5184 	unsigned long num_pages;
5185 	struct page *page;
5186 
5187 	num_pages = num_extent_pages(eb->start, eb->len);
5188 
5189 	for (i = 0; i < num_pages; i++) {
5190 		page = eb->pages[i];
5191 		if (!PageDirty(page))
5192 			continue;
5193 
5194 		lock_page(page);
5195 		WARN_ON(!PagePrivate(page));
5196 
5197 		clear_page_dirty_for_io(page);
5198 		spin_lock_irq(&page->mapping->tree_lock);
5199 		if (!PageDirty(page)) {
5200 			radix_tree_tag_clear(&page->mapping->page_tree,
5201 						page_index(page),
5202 						PAGECACHE_TAG_DIRTY);
5203 		}
5204 		spin_unlock_irq(&page->mapping->tree_lock);
5205 		ClearPageError(page);
5206 		unlock_page(page);
5207 	}
5208 	WARN_ON(atomic_read(&eb->refs) == 0);
5209 }
5210 
5211 int set_extent_buffer_dirty(struct extent_buffer *eb)
5212 {
5213 	unsigned long i;
5214 	unsigned long num_pages;
5215 	int was_dirty = 0;
5216 
5217 	check_buffer_tree_ref(eb);
5218 
5219 	was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
5220 
5221 	num_pages = num_extent_pages(eb->start, eb->len);
5222 	WARN_ON(atomic_read(&eb->refs) == 0);
5223 	WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
5224 
5225 	for (i = 0; i < num_pages; i++)
5226 		set_page_dirty(eb->pages[i]);
5227 	return was_dirty;
5228 }
5229 
5230 int clear_extent_buffer_uptodate(struct extent_buffer *eb)
5231 {
5232 	unsigned long i;
5233 	struct page *page;
5234 	unsigned long num_pages;
5235 
5236 	clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5237 	num_pages = num_extent_pages(eb->start, eb->len);
5238 	for (i = 0; i < num_pages; i++) {
5239 		page = eb->pages[i];
5240 		if (page)
5241 			ClearPageUptodate(page);
5242 	}
5243 	return 0;
5244 }
5245 
5246 int set_extent_buffer_uptodate(struct extent_buffer *eb)
5247 {
5248 	unsigned long i;
5249 	struct page *page;
5250 	unsigned long num_pages;
5251 
5252 	set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5253 	num_pages = num_extent_pages(eb->start, eb->len);
5254 	for (i = 0; i < num_pages; i++) {
5255 		page = eb->pages[i];
5256 		SetPageUptodate(page);
5257 	}
5258 	return 0;
5259 }
5260 
5261 int extent_buffer_uptodate(struct extent_buffer *eb)
5262 {
5263 	return test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5264 }
5265 
5266 int read_extent_buffer_pages(struct extent_io_tree *tree,
5267 			     struct extent_buffer *eb, u64 start, int wait,
5268 			     get_extent_t *get_extent, int mirror_num)
5269 {
5270 	unsigned long i;
5271 	unsigned long start_i;
5272 	struct page *page;
5273 	int err;
5274 	int ret = 0;
5275 	int locked_pages = 0;
5276 	int all_uptodate = 1;
5277 	unsigned long num_pages;
5278 	unsigned long num_reads = 0;
5279 	struct bio *bio = NULL;
5280 	unsigned long bio_flags = 0;
5281 
5282 	if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
5283 		return 0;
5284 
5285 	if (start) {
5286 		WARN_ON(start < eb->start);
5287 		start_i = (start >> PAGE_CACHE_SHIFT) -
5288 			(eb->start >> PAGE_CACHE_SHIFT);
5289 	} else {
5290 		start_i = 0;
5291 	}
5292 
5293 	num_pages = num_extent_pages(eb->start, eb->len);
5294 	for (i = start_i; i < num_pages; i++) {
5295 		page = eb->pages[i];
5296 		if (wait == WAIT_NONE) {
5297 			if (!trylock_page(page))
5298 				goto unlock_exit;
5299 		} else {
5300 			lock_page(page);
5301 		}
5302 		locked_pages++;
5303 		if (!PageUptodate(page)) {
5304 			num_reads++;
5305 			all_uptodate = 0;
5306 		}
5307 	}
5308 	if (all_uptodate) {
5309 		if (start_i == 0)
5310 			set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
5311 		goto unlock_exit;
5312 	}
5313 
5314 	clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
5315 	eb->read_mirror = 0;
5316 	atomic_set(&eb->io_pages, num_reads);
5317 	for (i = start_i; i < num_pages; i++) {
5318 		page = eb->pages[i];
5319 		if (!PageUptodate(page)) {
5320 			ClearPageError(page);
5321 			err = __extent_read_full_page(tree, page,
5322 						      get_extent, &bio,
5323 						      mirror_num, &bio_flags,
5324 						      READ | REQ_META);
5325 			if (err)
5326 				ret = err;
5327 		} else {
5328 			unlock_page(page);
5329 		}
5330 	}
5331 
5332 	if (bio) {
5333 		err = submit_one_bio(READ | REQ_META, bio, mirror_num,
5334 				     bio_flags);
5335 		if (err)
5336 			return err;
5337 	}
5338 
5339 	if (ret || wait != WAIT_COMPLETE)
5340 		return ret;
5341 
5342 	for (i = start_i; i < num_pages; i++) {
5343 		page = eb->pages[i];
5344 		wait_on_page_locked(page);
5345 		if (!PageUptodate(page))
5346 			ret = -EIO;
5347 	}
5348 
5349 	return ret;
5350 
5351 unlock_exit:
5352 	i = start_i;
5353 	while (locked_pages > 0) {
5354 		page = eb->pages[i];
5355 		i++;
5356 		unlock_page(page);
5357 		locked_pages--;
5358 	}
5359 	return ret;
5360 }
5361 
5362 void read_extent_buffer(struct extent_buffer *eb, void *dstv,
5363 			unsigned long start,
5364 			unsigned long len)
5365 {
5366 	size_t cur;
5367 	size_t offset;
5368 	struct page *page;
5369 	char *kaddr;
5370 	char *dst = (char *)dstv;
5371 	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5372 	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5373 
5374 	WARN_ON(start > eb->len);
5375 	WARN_ON(start + len > eb->start + eb->len);
5376 
5377 	offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5378 
5379 	while (len > 0) {
5380 		page = eb->pages[i];
5381 
5382 		cur = min(len, (PAGE_CACHE_SIZE - offset));
5383 		kaddr = page_address(page);
5384 		memcpy(dst, kaddr + offset, cur);
5385 
5386 		dst += cur;
5387 		len -= cur;
5388 		offset = 0;
5389 		i++;
5390 	}
5391 }
5392 
5393 int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
5394 			unsigned long start,
5395 			unsigned long len)
5396 {
5397 	size_t cur;
5398 	size_t offset;
5399 	struct page *page;
5400 	char *kaddr;
5401 	char __user *dst = (char __user *)dstv;
5402 	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5403 	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5404 	int ret = 0;
5405 
5406 	WARN_ON(start > eb->len);
5407 	WARN_ON(start + len > eb->start + eb->len);
5408 
5409 	offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5410 
5411 	while (len > 0) {
5412 		page = eb->pages[i];
5413 
5414 		cur = min(len, (PAGE_CACHE_SIZE - offset));
5415 		kaddr = page_address(page);
5416 		if (copy_to_user(dst, kaddr + offset, cur)) {
5417 			ret = -EFAULT;
5418 			break;
5419 		}
5420 
5421 		dst += cur;
5422 		len -= cur;
5423 		offset = 0;
5424 		i++;
5425 	}
5426 
5427 	return ret;
5428 }
5429 
5430 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
5431 			       unsigned long min_len, char **map,
5432 			       unsigned long *map_start,
5433 			       unsigned long *map_len)
5434 {
5435 	size_t offset = start & (PAGE_CACHE_SIZE - 1);
5436 	char *kaddr;
5437 	struct page *p;
5438 	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5439 	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5440 	unsigned long end_i = (start_offset + start + min_len - 1) >>
5441 		PAGE_CACHE_SHIFT;
5442 
5443 	if (i != end_i)
5444 		return -EINVAL;
5445 
5446 	if (i == 0) {
5447 		offset = start_offset;
5448 		*map_start = 0;
5449 	} else {
5450 		offset = 0;
5451 		*map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
5452 	}
5453 
5454 	if (start + min_len > eb->len) {
5455 		WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, "
5456 		       "wanted %lu %lu\n",
5457 		       eb->start, eb->len, start, min_len);
5458 		return -EINVAL;
5459 	}
5460 
5461 	p = eb->pages[i];
5462 	kaddr = page_address(p);
5463 	*map = kaddr + offset;
5464 	*map_len = PAGE_CACHE_SIZE - offset;
5465 	return 0;
5466 }
5467 
5468 int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
5469 			  unsigned long start,
5470 			  unsigned long len)
5471 {
5472 	size_t cur;
5473 	size_t offset;
5474 	struct page *page;
5475 	char *kaddr;
5476 	char *ptr = (char *)ptrv;
5477 	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5478 	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5479 	int ret = 0;
5480 
5481 	WARN_ON(start > eb->len);
5482 	WARN_ON(start + len > eb->start + eb->len);
5483 
5484 	offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5485 
5486 	while (len > 0) {
5487 		page = eb->pages[i];
5488 
5489 		cur = min(len, (PAGE_CACHE_SIZE - offset));
5490 
5491 		kaddr = page_address(page);
5492 		ret = memcmp(ptr, kaddr + offset, cur);
5493 		if (ret)
5494 			break;
5495 
5496 		ptr += cur;
5497 		len -= cur;
5498 		offset = 0;
5499 		i++;
5500 	}
5501 	return ret;
5502 }
5503 
5504 void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
5505 			 unsigned long start, unsigned long len)
5506 {
5507 	size_t cur;
5508 	size_t offset;
5509 	struct page *page;
5510 	char *kaddr;
5511 	char *src = (char *)srcv;
5512 	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5513 	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5514 
5515 	WARN_ON(start > eb->len);
5516 	WARN_ON(start + len > eb->start + eb->len);
5517 
5518 	offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5519 
5520 	while (len > 0) {
5521 		page = eb->pages[i];
5522 		WARN_ON(!PageUptodate(page));
5523 
5524 		cur = min(len, PAGE_CACHE_SIZE - offset);
5525 		kaddr = page_address(page);
5526 		memcpy(kaddr + offset, src, cur);
5527 
5528 		src += cur;
5529 		len -= cur;
5530 		offset = 0;
5531 		i++;
5532 	}
5533 }
5534 
5535 void memset_extent_buffer(struct extent_buffer *eb, char c,
5536 			  unsigned long start, unsigned long len)
5537 {
5538 	size_t cur;
5539 	size_t offset;
5540 	struct page *page;
5541 	char *kaddr;
5542 	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
5543 	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
5544 
5545 	WARN_ON(start > eb->len);
5546 	WARN_ON(start + len > eb->start + eb->len);
5547 
5548 	offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
5549 
5550 	while (len > 0) {
5551 		page = eb->pages[i];
5552 		WARN_ON(!PageUptodate(page));
5553 
5554 		cur = min(len, PAGE_CACHE_SIZE - offset);
5555 		kaddr = page_address(page);
5556 		memset(kaddr + offset, c, cur);
5557 
5558 		len -= cur;
5559 		offset = 0;
5560 		i++;
5561 	}
5562 }
5563 
5564 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
5565 			unsigned long dst_offset, unsigned long src_offset,
5566 			unsigned long len)
5567 {
5568 	u64 dst_len = dst->len;
5569 	size_t cur;
5570 	size_t offset;
5571 	struct page *page;
5572 	char *kaddr;
5573 	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
5574 	unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
5575 
5576 	WARN_ON(src->len != dst_len);
5577 
5578 	offset = (start_offset + dst_offset) &
5579 		(PAGE_CACHE_SIZE - 1);
5580 
5581 	while (len > 0) {
5582 		page = dst->pages[i];
5583 		WARN_ON(!PageUptodate(page));
5584 
5585 		cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
5586 
5587 		kaddr = page_address(page);
5588 		read_extent_buffer(src, kaddr + offset, src_offset, cur);
5589 
5590 		src_offset += cur;
5591 		len -= cur;
5592 		offset = 0;
5593 		i++;
5594 	}
5595 }
5596 
5597 static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
5598 {
5599 	unsigned long distance = (src > dst) ? src - dst : dst - src;
5600 	return distance < len;
5601 }
5602 
5603 static void copy_pages(struct page *dst_page, struct page *src_page,
5604 		       unsigned long dst_off, unsigned long src_off,
5605 		       unsigned long len)
5606 {
5607 	char *dst_kaddr = page_address(dst_page);
5608 	char *src_kaddr;
5609 	int must_memmove = 0;
5610 
5611 	if (dst_page != src_page) {
5612 		src_kaddr = page_address(src_page);
5613 	} else {
5614 		src_kaddr = dst_kaddr;
5615 		if (areas_overlap(src_off, dst_off, len))
5616 			must_memmove = 1;
5617 	}
5618 
5619 	if (must_memmove)
5620 		memmove(dst_kaddr + dst_off, src_kaddr + src_off, len);
5621 	else
5622 		memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
5623 }
5624 
5625 void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5626 			   unsigned long src_offset, unsigned long len)
5627 {
5628 	size_t cur;
5629 	size_t dst_off_in_page;
5630 	size_t src_off_in_page;
5631 	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
5632 	unsigned long dst_i;
5633 	unsigned long src_i;
5634 
5635 	if (src_offset + len > dst->len) {
5636 		btrfs_err(dst->fs_info,
5637 			"memmove bogus src_offset %lu move "
5638 		       "len %lu dst len %lu", src_offset, len, dst->len);
5639 		BUG_ON(1);
5640 	}
5641 	if (dst_offset + len > dst->len) {
5642 		btrfs_err(dst->fs_info,
5643 			"memmove bogus dst_offset %lu move "
5644 		       "len %lu dst len %lu", dst_offset, len, dst->len);
5645 		BUG_ON(1);
5646 	}
5647 
5648 	while (len > 0) {
5649 		dst_off_in_page = (start_offset + dst_offset) &
5650 			(PAGE_CACHE_SIZE - 1);
5651 		src_off_in_page = (start_offset + src_offset) &
5652 			(PAGE_CACHE_SIZE - 1);
5653 
5654 		dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
5655 		src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
5656 
5657 		cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
5658 					       src_off_in_page));
5659 		cur = min_t(unsigned long, cur,
5660 			(unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
5661 
5662 		copy_pages(dst->pages[dst_i], dst->pages[src_i],
5663 			   dst_off_in_page, src_off_in_page, cur);
5664 
5665 		src_offset += cur;
5666 		dst_offset += cur;
5667 		len -= cur;
5668 	}
5669 }
5670 
5671 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
5672 			   unsigned long src_offset, unsigned long len)
5673 {
5674 	size_t cur;
5675 	size_t dst_off_in_page;
5676 	size_t src_off_in_page;
5677 	unsigned long dst_end = dst_offset + len - 1;
5678 	unsigned long src_end = src_offset + len - 1;
5679 	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
5680 	unsigned long dst_i;
5681 	unsigned long src_i;
5682 
5683 	if (src_offset + len > dst->len) {
5684 		btrfs_err(dst->fs_info, "memmove bogus src_offset %lu move "
5685 		       "len %lu len %lu", src_offset, len, dst->len);
5686 		BUG_ON(1);
5687 	}
5688 	if (dst_offset + len > dst->len) {
5689 		btrfs_err(dst->fs_info, "memmove bogus dst_offset %lu move "
5690 		       "len %lu len %lu", dst_offset, len, dst->len);
5691 		BUG_ON(1);
5692 	}
5693 	if (dst_offset < src_offset) {
5694 		memcpy_extent_buffer(dst, dst_offset, src_offset, len);
5695 		return;
5696 	}
5697 	while (len > 0) {
5698 		dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
5699 		src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
5700 
5701 		dst_off_in_page = (start_offset + dst_end) &
5702 			(PAGE_CACHE_SIZE - 1);
5703 		src_off_in_page = (start_offset + src_end) &
5704 			(PAGE_CACHE_SIZE - 1);
5705 
5706 		cur = min_t(unsigned long, len, src_off_in_page + 1);
5707 		cur = min(cur, dst_off_in_page + 1);
5708 		copy_pages(dst->pages[dst_i], dst->pages[src_i],
5709 			   dst_off_in_page - cur + 1,
5710 			   src_off_in_page - cur + 1, cur);
5711 
5712 		dst_end -= cur;
5713 		src_end -= cur;
5714 		len -= cur;
5715 	}
5716 }
5717 
5718 int try_release_extent_buffer(struct page *page)
5719 {
5720 	struct extent_buffer *eb;
5721 
5722 	/*
5723 	 * We need to make sure noboody is attaching this page to an eb right
5724 	 * now.
5725 	 */
5726 	spin_lock(&page->mapping->private_lock);
5727 	if (!PagePrivate(page)) {
5728 		spin_unlock(&page->mapping->private_lock);
5729 		return 1;
5730 	}
5731 
5732 	eb = (struct extent_buffer *)page->private;
5733 	BUG_ON(!eb);
5734 
5735 	/*
5736 	 * This is a little awful but should be ok, we need to make sure that
5737 	 * the eb doesn't disappear out from under us while we're looking at
5738 	 * this page.
5739 	 */
5740 	spin_lock(&eb->refs_lock);
5741 	if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
5742 		spin_unlock(&eb->refs_lock);
5743 		spin_unlock(&page->mapping->private_lock);
5744 		return 0;
5745 	}
5746 	spin_unlock(&page->mapping->private_lock);
5747 
5748 	/*
5749 	 * If tree ref isn't set then we know the ref on this eb is a real ref,
5750 	 * so just return, this page will likely be freed soon anyway.
5751 	 */
5752 	if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
5753 		spin_unlock(&eb->refs_lock);
5754 		return 0;
5755 	}
5756 
5757 	return release_extent_buffer(eb);
5758 }
5759