summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/ordered-data.c
blob: da6d43eb41db0a3d8fe018483f85fe7485d84093 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include "ctree.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "extent_io.h"


static u64 entry_end(struct btrfs_ordered_extent *entry)
{
	if (entry->file_offset + entry->len < entry->file_offset)
		return (u64)-1;
	return entry->file_offset + entry->len;
}

static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
				   struct rb_node *node)
{
	struct rb_node ** p = &root->rb_node;
	struct rb_node * parent = NULL;
	struct btrfs_ordered_extent *entry;

	while(*p) {
		parent = *p;
		entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);

		if (file_offset < entry->file_offset)
			p = &(*p)->rb_left;
		else if (file_offset >= entry_end(entry))
			p = &(*p)->rb_right;
		else
			return parent;
	}

	rb_link_node(node, parent, p);
	rb_insert_color(node, root);
	return NULL;
}

static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
				     struct rb_node **prev_ret)
{
	struct rb_node * n = root->rb_node;
	struct rb_node *prev = NULL;
	struct rb_node *test;
	struct btrfs_ordered_extent *entry;
	struct btrfs_ordered_extent *prev_entry = NULL;

	while(n) {
		entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
		prev = n;
		prev_entry = entry;

		if (file_offset < entry->file_offset)
			n = n->rb_left;
		else if (file_offset >= entry_end(entry))
			n = n->rb_right;
		else
			return n;
	}
	if (!prev_ret)
		return NULL;

	while(prev && file_offset >= entry_end(prev_entry)) {
		test = rb_next(prev);
		if (!test)
			break;
		prev_entry = rb_entry(test, struct btrfs_ordered_extent,
				      rb_node);
		if (file_offset < entry_end(prev_entry))
			break;

		prev = test;
	}
	if (prev)
		prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
				      rb_node);
	while(prev && file_offset < entry_end(prev_entry)) {
		test = rb_prev(prev);
		if (!test)
			break;
		prev_entry = rb_entry(test, struct btrfs_ordered_extent,
				      rb_node);
		prev = test;
	}
	*prev_ret = prev;
	return NULL;
}

static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset)
{
	if (file_offset < entry->file_offset ||
	    entry->file_offset + entry->len <= file_offset)
		return 0;
	return 1;
}

static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
					  u64 file_offset)
{
	struct rb_root *root = &tree->tree;
	struct rb_node *prev;
	struct rb_node *ret;
	struct btrfs_ordered_extent *entry;

	if (tree->last) {
		entry = rb_entry(tree->last, struct btrfs_ordered_extent,
				 rb_node);
		if (offset_in_entry(entry, file_offset))
			return tree->last;
	}
	ret = __tree_search(root, file_offset, &prev);
	if (!ret)
		ret = prev;
	if (ret)
		tree->last = ret;
	return ret;
}

/* allocate and add a new ordered_extent into the per-inode tree.
 * file_offset is the logical offset in the file
 *
 * start is the disk block number of an extent already reserved in the
 * extent allocation tree
 *
 * len is the length of the extent
 *
 * This also sets the EXTENT_ORDERED bit on the range in the inode.
 *
 * The tree is given a single reference on the ordered extent that was
 * inserted.
 */
int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
			     u64 start, u64 len, int nocow)
{
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;
	struct btrfs_ordered_extent *entry;

	tree = &BTRFS_I(inode)->ordered_tree;
	entry = kzalloc(sizeof(*entry), GFP_NOFS);
	if (!entry)
		return -ENOMEM;

	mutex_lock(&tree->mutex);
	entry->file_offset = file_offset;
	entry->start = start;
	entry->len = len;
	entry->inode = inode;
	if (nocow)
		set_bit(BTRFS_ORDERED_NOCOW, &entry->flags);

	/* one ref for the tree */
	atomic_set(&entry->refs, 1);
	init_waitqueue_head(&entry->wait);
	INIT_LIST_HEAD(&entry->list);
	INIT_LIST_HEAD(&entry->root_extent_list);

	node = tree_insert(&tree->tree, file_offset,
			   &entry->rb_node);
	if (node) {
		printk("warning dup entry from add_ordered_extent\n");
		BUG();
	}
	set_extent_ordered(&BTRFS_I(inode)->io_tree, file_offset,
			   entry_end(entry) - 1, GFP_NOFS);

	spin_lock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
	list_add_tail(&entry->root_extent_list,
		      &BTRFS_I(inode)->root->fs_info->ordered_extents);
	spin_unlock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);

	mutex_unlock(&tree->mutex);
	BUG_ON(node);
	return 0;
}

/*
 * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
 * when an ordered extent is finished.  If the list covers more than one
 * ordered extent, it is split across multiples.
 */
int btrfs_add_ordered_sum(struct inode *inode,
			  struct btrfs_ordered_extent *entry,
			  struct btrfs_ordered_sum *sum)
{
	struct btrfs_ordered_inode_tree *tree;

	tree = &BTRFS_I(inode)->ordered_tree;
	mutex_lock(&tree->mutex);
	list_add_tail(&sum->list, &entry->list);
	mutex_unlock(&tree->mutex);
	return 0;
}

/*
 * this is used to account for finished IO across a given range
 * of the file.  The IO should not span ordered extents.  If
 * a given ordered_extent is completely done, 1 is returned, otherwise
 * 0.
 *
 * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
 * to make sure this function only returns 1 once for a given ordered extent.
 */
int btrfs_dec_test_ordered_pending(struct inode *inode,
				   u64 file_offset, u64 io_size)
{
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;
	struct btrfs_ordered_extent *entry;
	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
	int ret;

	tree = &BTRFS_I(inode)->ordered_tree;
	mutex_lock(&tree->mutex);
	clear_extent_ordered(io_tree, file_offset, file_offset + io_size - 1,
			     GFP_NOFS);
	node = tree_search(tree, file_offset);
	if (!node) {
		ret = 1;
		goto out;
	}

	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
	if (!offset_in_entry(entry, file_offset)) {
		ret = 1;
		goto out;
	}

	ret = test_range_bit(io_tree, entry->file_offset,
			     entry->file_offset + entry->len - 1,
			     EXTENT_ORDERED, 0);
	if (ret == 0)
		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
out:
	mutex_unlock(&tree->mutex);
	return ret == 0;
}

/*
 * used to drop a reference on an ordered extent.  This will free
 * the extent if the last reference is dropped
 */
int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
{
	struct list_head *cur;
	struct btrfs_ordered_sum *sum;

	if (atomic_dec_and_test(&entry->refs)) {
		while(!list_empty(&entry->list)) {
			cur = entry->list.next;
			sum = list_entry(cur, struct btrfs_ordered_sum, list);
			list_del(&sum->list);
			kfree(sum);
		}
		kfree(entry);
	}
	return 0;
}

/*
 * remove an ordered extent from the tree.  No references are dropped
 * but, anyone waiting on this extent is woken up.
 */
int btrfs_remove_ordered_extent(struct inode *inode,
				struct btrfs_ordered_extent *entry)
{
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;

	tree = &BTRFS_I(inode)->ordered_tree;
	mutex_lock(&tree->mutex);
	node = &entry->rb_node;
	rb_erase(node, &tree->tree);
	tree->last = NULL;
	set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);

	spin_lock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
	list_del_init(&entry->root_extent_list);
	spin_unlock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);

	mutex_unlock(&tree->mutex);
	wake_up(&entry->wait);
	return 0;
}

int btrfs_wait_ordered_extents(struct btrfs_root *root, int nocow_only)
{
	struct list_head splice;
	struct list_head *cur;
	struct list_head *tmp;
	struct btrfs_ordered_extent *ordered;
	struct inode *inode;

	INIT_LIST_HEAD(&splice);

	spin_lock(&root->fs_info->ordered_extent_lock);
	list_splice_init(&root->fs_info->ordered_extents, &splice);
	list_for_each_safe(cur, tmp, &splice) {
		cur = splice.next;
		ordered = list_entry(cur, struct btrfs_ordered_extent,
				     root_extent_list);
		if (nocow_only &&
		    !test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags)) {
			cond_resched_lock(&root->fs_info->ordered_extent_lock);
			continue;
		}

		list_del_init(&ordered->root_extent_list);
		atomic_inc(&ordered->refs);
		inode = ordered->inode;

		/*
		 * the inode can't go away until all the pages are gone
		 * and the pages won't go away while there is still
		 * an ordered extent and the ordered extent won't go
		 * away until it is off this list.  So, we can safely
		 * increment i_count here and call iput later
		 */
		atomic_inc(&inode->i_count);
		spin_unlock(&root->fs_info->ordered_extent_lock);

		btrfs_start_ordered_extent(inode, ordered, 1);
		btrfs_put_ordered_extent(ordered);
		iput(inode);

		spin_lock(&root->fs_info->ordered_extent_lock);
	}
	list_splice_init(&splice, &root->fs_info->ordered_extents);
	spin_unlock(&root->fs_info->ordered_extent_lock);
	return 0;
}

/*
 * Used to start IO or wait for a given ordered extent to finish.
 *
 * If wait is one, this effectively waits on page writeback for all the pages
 * in the extent, and it waits on the io completion code to insert
 * metadata into the btree corresponding to the extent
 */
void btrfs_start_ordered_extent(struct inode *inode,
				       struct btrfs_ordered_extent *entry,
				       int wait)
{
	u64 start = entry->file_offset;
	u64 end = start + entry->len - 1;

	/*
	 * pages in the range can be dirty, clean or writeback.  We
	 * start IO on any dirty ones so the wait doesn't stall waiting
	 * for pdflush to find them
	 */
	btrfs_fdatawrite_range(inode->i_mapping, start, end, WB_SYNC_NONE);
	if (wait)
		wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
						 &entry->flags));
}

/*
 * Used to wait on ordered extents across a large range of bytes.
 */
void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
{
	u64 end;
	u64 orig_end;
	u64 wait_end;
	struct btrfs_ordered_extent *ordered;

	if (start + len < start) {
		orig_end = INT_LIMIT(loff_t);
	} else {
		orig_end = start + len - 1;
		if (orig_end > INT_LIMIT(loff_t))
			orig_end = INT_LIMIT(loff_t);
	}
	wait_end = orig_end;
again:
	/* start IO across the range first to instantiate any delalloc
	 * extents
	 */
	btrfs_fdatawrite_range(inode->i_mapping, start, orig_end, WB_SYNC_NONE);

	btrfs_wait_on_page_writeback_range(inode->i_mapping,
					   start >> PAGE_CACHE_SHIFT,
					   orig_end >> PAGE_CACHE_SHIFT);

	end = orig_end;
	while(1) {
		ordered = btrfs_lookup_first_ordered_extent(inode, end);
		if (!ordered) {
			break;
		}
		if (ordered->file_offset > orig_end) {
			btrfs_put_ordered_extent(ordered);
			break;
		}
		if (ordered->file_offset + ordered->len < start) {
			btrfs_put_ordered_extent(ordered);
			break;
		}
		btrfs_start_ordered_extent(inode, ordered, 1);
		end = ordered->file_offset;
		btrfs_put_ordered_extent(ordered);
		if (end == 0 || end == start)
			break;
		end--;
	}
	if (test_range_bit(&BTRFS_I(inode)->io_tree, start, orig_end,
			   EXTENT_ORDERED | EXTENT_DELALLOC, 0)) {
		printk("inode %lu still ordered or delalloc after wait "
		       "%llu %llu\n", inode->i_ino,
		       (unsigned long long)start,
		       (unsigned long long)orig_end);
		goto again;
	}
}

/*
 * find an ordered extent corresponding to file_offset.  return NULL if
 * nothing is found, otherwise take a reference on the extent and return it
 */
struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
							 u64 file_offset)
{
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;
	struct btrfs_ordered_extent *entry = NULL;

	tree = &BTRFS_I(inode)->ordered_tree;
	mutex_lock(&tree->mutex);
	node = tree_search(tree, file_offset);
	if (!node)
		goto out;

	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
	if (!offset_in_entry(entry, file_offset))
		entry = NULL;
	if (entry)
		atomic_inc(&entry->refs);
out:
	mutex_unlock(&tree->mutex);
	return entry;
}

/*
 * lookup and return any extent before 'file_offset'.  NULL is returned
 * if none is found
 */
struct btrfs_ordered_extent *
btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset)
{
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;
	struct btrfs_ordered_extent *entry = NULL;

	tree = &BTRFS_I(inode)->ordered_tree;
	mutex_lock(&tree->mutex);
	node = tree_search(tree, file_offset);
	if (!node)
		goto out;

	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
	atomic_inc(&entry->refs);
out:
	mutex_unlock(&tree->mutex);
	return entry;
}

/*
 * After an extent is done, call this to conditionally update the on disk
 * i_size.  i_size is updated to cover any fully written part of the file.
 */
int btrfs_ordered_update_i_size(struct inode *inode,
				struct btrfs_ordered_extent *ordered)
{
	struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
	u64 disk_i_size;
	u64 new_i_size;
	u64 i_size_test;
	struct rb_node *node;
	struct btrfs_ordered_extent *test;

	mutex_lock(&tree->mutex);
	disk_i_size = BTRFS_I(inode)->disk_i_size;

	/*
	 * if the disk i_size is already at the inode->i_size, or
	 * this ordered extent is inside the disk i_size, we're done
	 */
	if (disk_i_size >= inode->i_size ||
	    ordered->file_offset + ordered->len <= disk_i_size) {
		goto out;
	}

	/*
	 * we can't update the disk_isize if there are delalloc bytes
	 * between disk_i_size and  this ordered extent
	 */
	if (test_range_bit(io_tree, disk_i_size,
			   ordered->file_offset + ordered->len - 1,
			   EXTENT_DELALLOC, 0)) {
		goto out;
	}
	/*
	 * walk backward from this ordered extent to disk_i_size.
	 * if we find an ordered extent then we can't update disk i_size
	 * yet
	 */
	node = &ordered->rb_node;
	while(1) {
		node = rb_prev(node);
		if (!node)
			break;
		test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
		if (test->file_offset + test->len <= disk_i_size)
			break;
		if (test->file_offset >= inode->i_size)
			break;
		if (test->file_offset >= disk_i_size)
			goto out;
	}
	new_i_size = min_t(u64, entry_end(ordered), i_size_read(inode));

	/*
	 * at this point, we know we can safely update i_size to at least
	 * the offset from this ordered extent.  But, we need to
	 * walk forward and see if ios from higher up in the file have
	 * finished.
	 */
	node = rb_next(&ordered->rb_node);
	i_size_test = 0;
	if (node) {
		/*
		 * do we have an area where IO might have finished
		 * between our ordered extent and the next one.
		 */
		test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
		if (test->file_offset > entry_end(ordered)) {
			i_size_test = test->file_offset;
		}
	} else {
		i_size_test = i_size_read(inode);
	}

	/*
	 * i_size_test is the end of a region after this ordered
	 * extent where there are no ordered extents.  As long as there
	 * are no delalloc bytes in this area, it is safe to update
	 * disk_i_size to the end of the region.
	 */
	if (i_size_test > entry_end(ordered) &&
	    !test_range_bit(io_tree, entry_end(ordered), i_size_test - 1,
			   EXTENT_DELALLOC, 0)) {
		new_i_size = min_t(u64, i_size_test, i_size_read(inode));
	}
	BTRFS_I(inode)->disk_i_size = new_i_size;
out:
	mutex_unlock(&tree->mutex);
	return 0;
}

/*
 * search the ordered extents for one corresponding to 'offset' and
 * try to find a checksum.  This is used because we allow pages to
 * be reclaimed before their checksum is actually put into the btree
 */
int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u32 *sum)
{
	struct btrfs_ordered_sum *ordered_sum;
	struct btrfs_sector_sum *sector_sums;
	struct btrfs_ordered_extent *ordered;
	struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
	struct list_head *cur;
	unsigned long num_sectors;
	unsigned long i;
	u32 sectorsize = BTRFS_I(inode)->root->sectorsize;
	int ret = 1;

	ordered = btrfs_lookup_ordered_extent(inode, offset);
	if (!ordered)
		return 1;

	mutex_lock(&tree->mutex);
	list_for_each_prev(cur, &ordered->list) {
		ordered_sum = list_entry(cur, struct btrfs_ordered_sum, list);
		if (offset >= ordered_sum->file_offset) {
			num_sectors = ordered_sum->len / sectorsize;
			sector_sums = ordered_sum->sums;
			for (i = 0; i < num_sectors; i++) {
				if (sector_sums[i].offset == offset) {
					*sum = sector_sums[i].sum;
					ret = 0;
					goto out;
				}
			}
		}
	}
out:
	mutex_unlock(&tree->mutex);
	btrfs_put_ordered_extent(ordered);
	return ret;
}


/**
 * taken from mm/filemap.c because it isn't exported
 *
 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
 * @mapping:	address space structure to write
 * @start:	offset in bytes where the range starts
 * @end:	offset in bytes where the range ends (inclusive)
 * @sync_mode:	enable synchronous operation
 *
 * Start writeback against all of a mapping's dirty pages that lie
 * within the byte offsets <start, end> inclusive.
 *
 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
 * opposed to a regular memory cleansing writeback.  The difference between
 * these two operations is that if a dirty page/buffer is encountered, it must
 * be waited upon, and not just skipped over.
 */
int btrfs_fdatawrite_range(struct address_space *mapping, loff_t start,
			   loff_t end, int sync_mode)
{
	struct writeback_control wbc = {
		.sync_mode = sync_mode,
		.nr_to_write = mapping->nrpages * 2,
		.range_start = start,
		.range_end = end,
		.for_writepages = 1,
	};
	return btrfs_writepages(mapping, &wbc);
}

/**
 * taken from mm/filemap.c because it isn't exported
 *
 * wait_on_page_writeback_range - wait for writeback to complete
 * @mapping:	target address_space
 * @start:	beginning page index
 * @end:	ending page index
 *
 * Wait for writeback to complete against pages indexed by start->end
 * inclusive
 */
int btrfs_wait_on_page_writeback_range(struct address_space *mapping,
				       pgoff_t start, pgoff_t end)
{
	struct pagevec pvec;
	int nr_pages;
	int ret = 0;
	pgoff_t index;

	if (end < start)
		return 0;

	pagevec_init(&pvec, 0);
	index = start;
	while ((index <= end) &&
			(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
			PAGECACHE_TAG_WRITEBACK,
			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
		unsigned i;

		for (i = 0; i < nr_pages; i++) {
			struct page *page = pvec.pages[i];

			/* until radix tree lookup accepts end_index */
			if (page->index > end)
				continue;

			wait_on_page_writeback(page);
			if (PageError(page))
				ret = -EIO;
		}
		pagevec_release(&pvec);
		cond_resched();
	}

	/* Check for outstanding write errors */
	if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
		ret = -ENOSPC;
	if (test_and_clear_bit(AS_EIO, &mapping->flags))
		ret = -EIO;

	return ret;
}
OpenPOWER on IntegriCloud