aboutsummaryrefslogtreecommitdiff
path: root/fs/f2fs/data.c
blob: 8e8b14d714fc8c024d763a78da0385d4485f6a96 (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
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
/*
 * fs/f2fs/data.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/prefetch.h>

#include "f2fs.h"
#include "node.h"
#include "segment.h"
#include <trace/events/f2fs.h>

/*
 * Lock ordering for the change of data block address:
 * ->data_page
 *  ->node_page
 *    update block addresses in the node page
 */
static void __set_data_blkaddr(struct dnode_of_data *dn, block_t new_addr)
{
	struct f2fs_node *rn;
	__le32 *addr_array;
	struct page *node_page = dn->node_page;
	unsigned int ofs_in_node = dn->ofs_in_node;

	wait_on_page_writeback(node_page);

	rn = (struct f2fs_node *)page_address(node_page);

	/* Get physical address of data block */
	addr_array = blkaddr_in_node(rn);
	addr_array[ofs_in_node] = cpu_to_le32(new_addr);
	set_page_dirty(node_page);
}

int reserve_new_block(struct dnode_of_data *dn)
{
	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);

	if (is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC))
		return -EPERM;
	if (!inc_valid_block_count(sbi, dn->inode, 1))
		return -ENOSPC;

	__set_data_blkaddr(dn, NEW_ADDR);
	dn->data_blkaddr = NEW_ADDR;
	sync_inode_page(dn);
	return 0;
}

static int check_extent_cache(struct inode *inode, pgoff_t pgofs,
					struct buffer_head *bh_result)
{
	struct f2fs_inode_info *fi = F2FS_I(inode);
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	pgoff_t start_fofs, end_fofs;
	block_t start_blkaddr;

	read_lock(&fi->ext.ext_lock);
	if (fi->ext.len == 0) {
		read_unlock(&fi->ext.ext_lock);
		return 0;
	}

	sbi->total_hit_ext++;
	start_fofs = fi->ext.fofs;
	end_fofs = fi->ext.fofs + fi->ext.len - 1;
	start_blkaddr = fi->ext.blk_addr;

	if (pgofs >= start_fofs && pgofs <= end_fofs) {
		unsigned int blkbits = inode->i_sb->s_blocksize_bits;
		size_t count;

		clear_buffer_new(bh_result);
		map_bh(bh_result, inode->i_sb,
				start_blkaddr + pgofs - start_fofs);
		count = end_fofs - pgofs + 1;
		if (count < (UINT_MAX >> blkbits))
			bh_result->b_size = (count << blkbits);
		else
			bh_result->b_size = UINT_MAX;

		sbi->read_hit_ext++;
		read_unlock(&fi->ext.ext_lock);
		return 1;
	}
	read_unlock(&fi->ext.ext_lock);
	return 0;
}

void update_extent_cache(block_t blk_addr, struct dnode_of_data *dn)
{
	struct f2fs_inode_info *fi = F2FS_I(dn->inode);
	pgoff_t fofs, start_fofs, end_fofs;
	block_t start_blkaddr, end_blkaddr;

	BUG_ON(blk_addr == NEW_ADDR);
	fofs = start_bidx_of_node(ofs_of_node(dn->node_page)) + dn->ofs_in_node;

	/* Update the page address in the parent node */
	__set_data_blkaddr(dn, blk_addr);

	write_lock(&fi->ext.ext_lock);

	start_fofs = fi->ext.fofs;
	end_fofs = fi->ext.fofs + fi->ext.len - 1;
	start_blkaddr = fi->ext.blk_addr;
	end_blkaddr = fi->ext.blk_addr + fi->ext.len - 1;

	/* Drop and initialize the matched extent */
	if (fi->ext.len == 1 && fofs == start_fofs)
		fi->ext.len = 0;

	/* Initial extent */
	if (fi->ext.len == 0) {
		if (blk_addr != NULL_ADDR) {
			fi->ext.fofs = fofs;
			fi->ext.blk_addr = blk_addr;
			fi->ext.len = 1;
		}
		goto end_update;
	}

	/* Front merge */
	if (fofs == start_fofs - 1 && blk_addr == start_blkaddr - 1) {
		fi->ext.fofs--;
		fi->ext.blk_addr--;
		fi->ext.len++;
		goto end_update;
	}

	/* Back merge */
	if (fofs == end_fofs + 1 && blk_addr == end_blkaddr + 1) {
		fi->ext.len++;
		goto end_update;
	}

	/* Split the existing extent */
	if (fi->ext.len > 1 &&
		fofs >= start_fofs && fofs <= end_fofs) {
		if ((end_fofs - fofs) < (fi->ext.len >> 1)) {
			fi->ext.len = fofs - start_fofs;
		} else {
			fi->ext.fofs = fofs + 1;
			fi->ext.blk_addr = start_blkaddr +
					fofs - start_fofs + 1;
			fi->ext.len -= fofs - start_fofs + 1;
		}
		goto end_update;
	}
	write_unlock(&fi->ext.ext_lock);
	return;

end_update:
	write_unlock(&fi->ext.ext_lock);
	sync_inode_page(dn);
	return;
}

struct page *find_data_page(struct inode *inode, pgoff_t index)
{
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	struct address_space *mapping = inode->i_mapping;
	struct dnode_of_data dn;
	struct page *page;
	int err;

	page = find_get_page(mapping, index);
	if (page && PageUptodate(page))
		return page;
	f2fs_put_page(page, 0);

	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
	if (err)
		return ERR_PTR(err);
	f2fs_put_dnode(&dn);

	if (dn.data_blkaddr == NULL_ADDR)
		return ERR_PTR(-ENOENT);

	/* By fallocate(), there is no cached page, but with NEW_ADDR */
	if (dn.data_blkaddr == NEW_ADDR)
		return ERR_PTR(-EINVAL);

	page = grab_cache_page(mapping, index);
	if (!page)
		return ERR_PTR(-ENOMEM);

	if (PageUptodate(page)) {
		unlock_page(page);
		return page;
	}

	err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
	wait_on_page_locked(page);
	if (!PageUptodate(page)) {
		f2fs_put_page(page, 0);
		return ERR_PTR(-EIO);
	}
	return page;
}

/*
 * If it tries to access a hole, return an error.
 * Because, the callers, functions in dir.c and GC, should be able to know
 * whether this page exists or not.
 */
struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
{
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	struct address_space *mapping = inode->i_mapping;
	struct dnode_of_data dn;
	struct page *page;
	int err;

	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
	if (err)
		return ERR_PTR(err);
	f2fs_put_dnode(&dn);

	if (dn.data_blkaddr == NULL_ADDR)
		return ERR_PTR(-ENOENT);

	page = grab_cache_page(mapping, index);
	if (!page)
		return ERR_PTR(-ENOMEM);

	if (PageUptodate(page))
		return page;

	BUG_ON(dn.data_blkaddr == NEW_ADDR);
	BUG_ON(dn.data_blkaddr == NULL_ADDR);

	err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
	if (err)
		return ERR_PTR(err);

	lock_page(page);
	if (!PageUptodate(page)) {
		f2fs_put_page(page, 1);
		return ERR_PTR(-EIO);
	}
	return page;
}

/*
 * Caller ensures that this data page is never allocated.
 * A new zero-filled data page is allocated in the page cache.
 *
 * Also, caller should grab and release a mutex by calling mutex_lock_op() and
 * mutex_unlock_op().
 */
struct page *get_new_data_page(struct inode *inode, pgoff_t index,
						bool new_i_size)
{
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	struct address_space *mapping = inode->i_mapping;
	struct page *page;
	struct dnode_of_data dn;
	int err;

	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, index, ALLOC_NODE);
	if (err)
		return ERR_PTR(err);

	if (dn.data_blkaddr == NULL_ADDR) {
		if (reserve_new_block(&dn)) {
			f2fs_put_dnode(&dn);
			return ERR_PTR(-ENOSPC);
		}
	}
	f2fs_put_dnode(&dn);

	page = grab_cache_page(mapping, index);
	if (!page)
		return ERR_PTR(-ENOMEM);

	if (PageUptodate(page))
		return page;

	if (dn.data_blkaddr == NEW_ADDR) {
		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
		SetPageUptodate(page);
	} else {
		err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
		if (err)
			return ERR_PTR(err);
		lock_page(page);
		if (!PageUptodate(page)) {
			f2fs_put_page(page, 1);
			return ERR_PTR(-EIO);
		}
	}

	if (new_i_size &&
		i_size_read(inode) < ((index + 1) << PAGE_CACHE_SHIFT)) {
		i_size_write(inode, ((index + 1) << PAGE_CACHE_SHIFT));
		mark_inode_dirty_sync(inode);
	}
	return page;
}

static void read_end_io(struct bio *bio, int err)
{
	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;

	do {
		struct page *page = bvec->bv_page;

		if (--bvec >= bio->bi_io_vec)
			prefetchw(&bvec->bv_page->flags);

		if (uptodate) {
			SetPageUptodate(page);
		} else {
			ClearPageUptodate(page);
			SetPageError(page);
		}
		unlock_page(page);
	} while (bvec >= bio->bi_io_vec);
	kfree(bio->bi_private);
	bio_put(bio);
}

/*
 * Fill the locked page with data located in the block address.
 * Return unlocked page.
 */
int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
					block_t blk_addr, int type)
{
	struct block_device *bdev = sbi->sb->s_bdev;
	struct bio *bio;

	trace_f2fs_readpage(page, blk_addr, type);

	down_read(&sbi->bio_sem);

	/* Allocate a new bio */
	bio = f2fs_bio_alloc(bdev, 1);

	/* Initialize the bio */
	bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
	bio->bi_end_io = read_end_io;

	if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
		kfree(bio->bi_private);
		bio_put(bio);
		up_read(&sbi->bio_sem);
		f2fs_put_page(page, 1);
		return -EFAULT;
	}

	submit_bio(type, bio);
	up_read(&sbi->bio_sem);
	return 0;
}

/*
 * This function should be used by the data read flow only where it
 * does not check the "create" flag that indicates block allocation.
 * The reason for this special functionality is to exploit VFS readahead
 * mechanism.
 */
static int get_data_block_ro(struct inode *inode, sector_t iblock,
			struct buffer_head *bh_result, int create)
{
	unsigned int blkbits = inode->i_sb->s_blocksize_bits;
	unsigned maxblocks = bh_result->b_size >> blkbits;
	struct dnode_of_data dn;
	pgoff_t pgofs;
	int err;

	/* Get the page offset from the block offset(iblock) */
	pgofs =	(pgoff_t)(iblock >> (PAGE_CACHE_SHIFT - blkbits));

	if (check_extent_cache(inode, pgofs, bh_result)) {
		trace_f2fs_get_data_block(inode, iblock, bh_result, 0);
		return 0;
	}

	/* When reading holes, we need its node page */
	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, pgofs, LOOKUP_NODE_RA);
	if (err) {
		trace_f2fs_get_data_block(inode, iblock, bh_result, err);
		return (err == -ENOENT) ? 0 : err;
	}

	/* It does not support data allocation */
	BUG_ON(create);

	if (dn.data_blkaddr != NEW_ADDR && dn.data_blkaddr != NULL_ADDR) {
		int i;
		unsigned int end_offset;

		end_offset = IS_INODE(dn.node_page) ?
				ADDRS_PER_INODE :
				ADDRS_PER_BLOCK;

		clear_buffer_new(bh_result);

		/* Give more consecutive addresses for the read ahead */
		for (i = 0; i < end_offset - dn.ofs_in_node; i++)
			if (((datablock_addr(dn.node_page,
							dn.ofs_in_node + i))
				!= (dn.data_blkaddr + i)) || maxblocks == i)
				break;
		map_bh(bh_result, inode->i_sb, dn.data_blkaddr);
		bh_result->b_size = (i << blkbits);
	}
	f2fs_put_dnode(&dn);
	trace_f2fs_get_data_block(inode, iblock, bh_result, 0);
	return 0;
}

static int f2fs_read_data_page(struct file *file, struct page *page)
{
	return mpage_readpage(page, get_data_block_ro);
}

static int f2fs_read_data_pages(struct file *file,
			struct address_space *mapping,
			struct list_head *pages, unsigned nr_pages)
{
	return mpage_readpages(mapping, pages, nr_pages, get_data_block_ro);
}

int do_write_data_page(struct page *page)
{
	struct inode *inode = page->mapping->host;
	block_t old_blk_addr, new_blk_addr;
	struct dnode_of_data dn;
	int err = 0;

	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
	if (err)
		return err;

	old_blk_addr = dn.data_blkaddr;

	/* This page is already truncated */
	if (old_blk_addr == NULL_ADDR)
		goto out_writepage;

	set_page_writeback(page);

	/*
	 * If current allocation needs SSR,
	 * it had better in-place writes for updated data.
	 */
	if (old_blk_addr != NEW_ADDR && !is_cold_data(page) &&
				need_inplace_update(inode)) {
		rewrite_data_page(F2FS_SB(inode->i_sb), page,
						old_blk_addr);
	} else {
		write_data_page(inode, page, &dn,
				old_blk_addr, &new_blk_addr);
		update_extent_cache(new_blk_addr, &dn);
	}
out_writepage:
	f2fs_put_dnode(&dn);
	return err;
}

static int f2fs_write_data_page(struct page *page,
					struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	loff_t i_size = i_size_read(inode);
	const pgoff_t end_index = ((unsigned long long) i_size)
							>> PAGE_CACHE_SHIFT;
	unsigned offset;
	bool need_balance_fs = false;
	int err = 0;

	if (page->index < end_index)
		goto write;

	/*
	 * If the offset is out-of-range of file size,
	 * this page does not have to be written to disk.
	 */
	offset = i_size & (PAGE_CACHE_SIZE - 1);
	if ((page->index >= end_index + 1) || !offset) {
		if (S_ISDIR(inode->i_mode)) {
			dec_page_count(sbi, F2FS_DIRTY_DENTS);
			inode_dec_dirty_dents(inode);
		}
		goto out;
	}

	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
write:
	if (sbi->por_doing) {
		err = AOP_WRITEPAGE_ACTIVATE;
		goto redirty_out;
	}

	/* Dentry blocks are controlled by checkpoint */
	if (S_ISDIR(inode->i_mode)) {
		dec_page_count(sbi, F2FS_DIRTY_DENTS);
		inode_dec_dirty_dents(inode);
		err = do_write_data_page(page);
	} else {
		int ilock = mutex_lock_op(sbi);
		err = do_write_data_page(page);
		mutex_unlock_op(sbi, ilock);
		need_balance_fs = true;
	}
	if (err == -ENOENT)
		goto out;
	else if (err)
		goto redirty_out;

	if (wbc->for_reclaim)
		f2fs_submit_bio(sbi, DATA, true);

	clear_cold_data(page);
out:
	unlock_page(page);
	if (need_balance_fs)
		f2fs_balance_fs(sbi);
	return 0;

redirty_out:
	wbc->pages_skipped++;
	set_page_dirty(page);
	return err;
}

#define MAX_DESIRED_PAGES_WP	4096

static int __f2fs_writepage(struct page *page, struct writeback_control *wbc,
			void *data)
{
	struct address_space *mapping = data;
	int ret = mapping->a_ops->writepage(page, wbc);
	mapping_set_error(mapping, ret);
	return ret;
}

static int f2fs_write_data_pages(struct address_space *mapping,
			    struct writeback_control *wbc)
{
	struct inode *inode = mapping->host;
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	int ret;
	long excess_nrtw = 0, desired_nrtw;

	/* deal with chardevs and other special file */
	if (!mapping->a_ops->writepage)
		return 0;

	if (wbc->nr_to_write < MAX_DESIRED_PAGES_WP) {
		desired_nrtw = MAX_DESIRED_PAGES_WP;
		excess_nrtw = desired_nrtw - wbc->nr_to_write;
		wbc->nr_to_write = desired_nrtw;
	}

	if (!S_ISDIR(inode->i_mode))
		mutex_lock(&sbi->writepages);
	ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
	if (!S_ISDIR(inode->i_mode))
		mutex_unlock(&sbi->writepages);
	f2fs_submit_bio(sbi, DATA, (wbc->sync_mode == WB_SYNC_ALL));

	remove_dirty_dir_inode(inode);

	wbc->nr_to_write -= excess_nrtw;
	return ret;
}

static int f2fs_write_begin(struct file *file, struct address_space *mapping,
		loff_t pos, unsigned len, unsigned flags,
		struct page **pagep, void **fsdata)
{
	struct inode *inode = mapping->host;
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	struct page *page;
	pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
	struct dnode_of_data dn;
	int err = 0;
	int ilock;

	/* for nobh_write_end */
	*fsdata = NULL;

	f2fs_balance_fs(sbi);

	page = grab_cache_page_write_begin(mapping, index, flags);
	if (!page)
		return -ENOMEM;
	*pagep = page;

	ilock = mutex_lock_op(sbi);

	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, index, ALLOC_NODE);
	if (err)
		goto err;

	if (dn.data_blkaddr == NULL_ADDR)
		err = reserve_new_block(&dn);

	f2fs_put_dnode(&dn);
	if (err)
		goto err;

	mutex_unlock_op(sbi, ilock);

	if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
		return 0;

	if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
		unsigned start = pos & (PAGE_CACHE_SIZE - 1);
		unsigned end = start + len;

		/* Reading beyond i_size is simple: memset to zero */
		zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
		goto out;
	}

	if (dn.data_blkaddr == NEW_ADDR) {
		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
	} else {
		err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
		if (err)
			return err;
		lock_page(page);
		if (!PageUptodate(page)) {
			f2fs_put_page(page, 1);
			return -EIO;
		}
	}
out:
	SetPageUptodate(page);
	clear_cold_data(page);
	return 0;

err:
	mutex_unlock_op(sbi, ilock);
	f2fs_put_page(page, 1);
	return err;
}

static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
		const struct iovec *iov, loff_t offset, unsigned long nr_segs)
{
	struct file *file = iocb->ki_filp;
	struct inode *inode = file->f_mapping->host;

	if (rw == WRITE)
		return 0;

	/* Needs synchronization with the cleaner */
	return blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
						  get_data_block_ro);
}

static void f2fs_invalidate_data_page(struct page *page, unsigned long offset)
{
	struct inode *inode = page->mapping->host;
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	if (S_ISDIR(inode->i_mode) && PageDirty(page)) {
		dec_page_count(sbi, F2FS_DIRTY_DENTS);
		inode_dec_dirty_dents(inode);
	}
	ClearPagePrivate(page);
}

static int f2fs_release_data_page(struct page *page, gfp_t wait)
{
	ClearPagePrivate(page);
	return 1;
}

static int f2fs_set_data_page_dirty(struct page *page)
{
	struct address_space *mapping = page->mapping;
	struct inode *inode = mapping->host;

	SetPageUptodate(page);
	if (!PageDirty(page)) {
		__set_page_dirty_nobuffers(page);
		set_dirty_dir_page(inode, page);
		return 1;
	}
	return 0;
}

static sector_t f2fs_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping, block, get_data_block_ro);
}

const struct address_space_operations f2fs_dblock_aops = {
	.readpage	= f2fs_read_data_page,
	.readpages	= f2fs_read_data_pages,
	.writepage	= f2fs_write_data_page,
	.writepages	= f2fs_write_data_pages,
	.write_begin	= f2fs_write_begin,
	.write_end	= nobh_write_end,
	.set_page_dirty	= f2fs_set_data_page_dirty,
	.invalidatepage	= f2fs_invalidate_data_page,
	.releasepage	= f2fs_release_data_page,
	.direct_IO	= f2fs_direct_IO,
	.bmap		= f2fs_bmap,
};