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