aboutsummaryrefslogtreecommitdiff
path: root/fs/f2fs/gc.c
blob: b0ec721e984a324e3e239d4cdfe946cb0a5b8df0 (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
729
730
/*
 * fs/f2fs/gc.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/module.h>
#include <linux/backing-dev.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/f2fs_fs.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/blkdev.h>

#include "f2fs.h"
#include "node.h"
#include "segment.h"
#include "gc.h"

static struct kmem_cache *winode_slab;

static int gc_thread_func(void *data)
{
	struct f2fs_sb_info *sbi = data;
	wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
	long wait_ms;

	wait_ms = GC_THREAD_MIN_SLEEP_TIME;

	do {
		if (try_to_freeze())
			continue;
		else
			wait_event_interruptible_timeout(*wq,
						kthread_should_stop(),
						msecs_to_jiffies(wait_ms));
		if (kthread_should_stop())
			break;

		f2fs_balance_fs(sbi);

		if (!test_opt(sbi, BG_GC))
			continue;

		/*
		 * [GC triggering condition]
		 * 0. GC is not conducted currently.
		 * 1. There are enough dirty segments.
		 * 2. IO subsystem is idle by checking the # of writeback pages.
		 * 3. IO subsystem is idle by checking the # of requests in
		 *    bdev's request list.
		 *
		 * Note) We have to avoid triggering GCs too much frequently.
		 * Because it is possible that some segments can be
		 * invalidated soon after by user update or deletion.
		 * So, I'd like to wait some time to collect dirty segments.
		 */
		if (!mutex_trylock(&sbi->gc_mutex))
			continue;

		if (!is_idle(sbi)) {
			wait_ms = increase_sleep_time(wait_ms);
			mutex_unlock(&sbi->gc_mutex);
			continue;
		}

		if (has_enough_invalid_blocks(sbi))
			wait_ms = decrease_sleep_time(wait_ms);
		else
			wait_ms = increase_sleep_time(wait_ms);

		sbi->bg_gc++;

		if (f2fs_gc(sbi, 1) == GC_NONE)
			wait_ms = GC_THREAD_NOGC_SLEEP_TIME;
		else if (wait_ms == GC_THREAD_NOGC_SLEEP_TIME)
			wait_ms = GC_THREAD_MAX_SLEEP_TIME;

	} while (!kthread_should_stop());
	return 0;
}

int start_gc_thread(struct f2fs_sb_info *sbi)
{
	struct f2fs_gc_kthread *gc_th;

	gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
	if (!gc_th)
		return -ENOMEM;

	sbi->gc_thread = gc_th;
	init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
	sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
				GC_THREAD_NAME);
	if (IS_ERR(gc_th->f2fs_gc_task)) {
		kfree(gc_th);
		return -ENOMEM;
	}
	return 0;
}

void stop_gc_thread(struct f2fs_sb_info *sbi)
{
	struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
	if (!gc_th)
		return;
	kthread_stop(gc_th->f2fs_gc_task);
	kfree(gc_th);
	sbi->gc_thread = NULL;
}

static int select_gc_type(int gc_type)
{
	return (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
}

static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
			int type, struct victim_sel_policy *p)
{
	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

	if (p->alloc_mode) {
		p->gc_mode = GC_GREEDY;
		p->dirty_segmap = dirty_i->dirty_segmap[type];
		p->ofs_unit = 1;
	} else {
		p->gc_mode = select_gc_type(gc_type);
		p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
		p->ofs_unit = sbi->segs_per_sec;
	}
	p->offset = sbi->last_victim[p->gc_mode];
}

static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
				struct victim_sel_policy *p)
{
	if (p->gc_mode == GC_GREEDY)
		return (1 << sbi->log_blocks_per_seg) * p->ofs_unit;
	else if (p->gc_mode == GC_CB)
		return UINT_MAX;
	else /* No other gc_mode */
		return 0;
}

static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
{
	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
	unsigned int segno;

	/*
	 * If the gc_type is FG_GC, we can select victim segments
	 * selected by background GC before.
	 * Those segments guarantee they have small valid blocks.
	 */
	segno = find_next_bit(dirty_i->victim_segmap[BG_GC],
						TOTAL_SEGS(sbi), 0);
	if (segno < TOTAL_SEGS(sbi)) {
		clear_bit(segno, dirty_i->victim_segmap[BG_GC]);
		return segno;
	}
	return NULL_SEGNO;
}

static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
{
	struct sit_info *sit_i = SIT_I(sbi);
	unsigned int secno = GET_SECNO(sbi, segno);
	unsigned int start = secno * sbi->segs_per_sec;
	unsigned long long mtime = 0;
	unsigned int vblocks;
	unsigned char age = 0;
	unsigned char u;
	unsigned int i;

	for (i = 0; i < sbi->segs_per_sec; i++)
		mtime += get_seg_entry(sbi, start + i)->mtime;
	vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);

	mtime = div_u64(mtime, sbi->segs_per_sec);
	vblocks = div_u64(vblocks, sbi->segs_per_sec);

	u = (vblocks * 100) >> sbi->log_blocks_per_seg;

	/* Handle if the system time is changed by user */
	if (mtime < sit_i->min_mtime)
		sit_i->min_mtime = mtime;
	if (mtime > sit_i->max_mtime)
		sit_i->max_mtime = mtime;
	if (sit_i->max_mtime != sit_i->min_mtime)
		age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
				sit_i->max_mtime - sit_i->min_mtime);

	return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
}

static unsigned int get_gc_cost(struct f2fs_sb_info *sbi, unsigned int segno,
					struct victim_sel_policy *p)
{
	if (p->alloc_mode == SSR)
		return get_seg_entry(sbi, segno)->ckpt_valid_blocks;

	/* alloc_mode == LFS */
	if (p->gc_mode == GC_GREEDY)
		return get_valid_blocks(sbi, segno, sbi->segs_per_sec);
	else
		return get_cb_cost(sbi, segno);
}

/*
 * This function is called from two pathes.
 * One is garbage collection and the other is SSR segment selection.
 * When it is called during GC, it just gets a victim segment
 * and it does not remove it from dirty seglist.
 * When it is called from SSR segment selection, it finds a segment
 * which has minimum valid blocks and removes it from dirty seglist.
 */
static int get_victim_by_default(struct f2fs_sb_info *sbi,
		unsigned int *result, int gc_type, int type, char alloc_mode)
{
	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
	struct victim_sel_policy p;
	unsigned int segno;
	int nsearched = 0;

	p.alloc_mode = alloc_mode;
	select_policy(sbi, gc_type, type, &p);

	p.min_segno = NULL_SEGNO;
	p.min_cost = get_max_cost(sbi, &p);

	mutex_lock(&dirty_i->seglist_lock);

	if (p.alloc_mode == LFS && gc_type == FG_GC) {
		p.min_segno = check_bg_victims(sbi);
		if (p.min_segno != NULL_SEGNO)
			goto got_it;
	}

	while (1) {
		unsigned long cost;

		segno = find_next_bit(p.dirty_segmap,
						TOTAL_SEGS(sbi), p.offset);
		if (segno >= TOTAL_SEGS(sbi)) {
			if (sbi->last_victim[p.gc_mode]) {
				sbi->last_victim[p.gc_mode] = 0;
				p.offset = 0;
				continue;
			}
			break;
		}
		p.offset = ((segno / p.ofs_unit) * p.ofs_unit) + p.ofs_unit;

		if (test_bit(segno, dirty_i->victim_segmap[FG_GC]))
			continue;
		if (gc_type == BG_GC &&
				test_bit(segno, dirty_i->victim_segmap[BG_GC]))
			continue;
		if (IS_CURSEC(sbi, GET_SECNO(sbi, segno)))
			continue;

		cost = get_gc_cost(sbi, segno, &p);

		if (p.min_cost > cost) {
			p.min_segno = segno;
			p.min_cost = cost;
		}

		if (cost == get_max_cost(sbi, &p))
			continue;

		if (nsearched++ >= MAX_VICTIM_SEARCH) {
			sbi->last_victim[p.gc_mode] = segno;
			break;
		}
	}
got_it:
	if (p.min_segno != NULL_SEGNO) {
		*result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
		if (p.alloc_mode == LFS) {
			int i;
			for (i = 0; i < p.ofs_unit; i++)
				set_bit(*result + i,
					dirty_i->victim_segmap[gc_type]);
		}
	}
	mutex_unlock(&dirty_i->seglist_lock);

	return (p.min_segno == NULL_SEGNO) ? 0 : 1;
}

static const struct victim_selection default_v_ops = {
	.get_victim = get_victim_by_default,
};

static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist)
{
	struct list_head *this;
	struct inode_entry *ie;

	list_for_each(this, ilist) {
		ie = list_entry(this, struct inode_entry, list);
		if (ie->inode->i_ino == ino)
			return ie->inode;
	}
	return NULL;
}

static void add_gc_inode(struct inode *inode, struct list_head *ilist)
{
	struct list_head *this;
	struct inode_entry *new_ie, *ie;

	list_for_each(this, ilist) {
		ie = list_entry(this, struct inode_entry, list);
		if (ie->inode == inode) {
			iput(inode);
			return;
		}
	}
repeat:
	new_ie = kmem_cache_alloc(winode_slab, GFP_NOFS);
	if (!new_ie) {
		cond_resched();
		goto repeat;
	}
	new_ie->inode = inode;
	list_add_tail(&new_ie->list, ilist);
}

static void put_gc_inode(struct list_head *ilist)
{
	struct inode_entry *ie, *next_ie;
	list_for_each_entry_safe(ie, next_ie, ilist, list) {
		iput(ie->inode);
		list_del(&ie->list);
		kmem_cache_free(winode_slab, ie);
	}
}

static int check_valid_map(struct f2fs_sb_info *sbi,
				unsigned int segno, int offset)
{
	struct sit_info *sit_i = SIT_I(sbi);
	struct seg_entry *sentry;
	int ret;

	mutex_lock(&sit_i->sentry_lock);
	sentry = get_seg_entry(sbi, segno);
	ret = f2fs_test_bit(offset, sentry->cur_valid_map);
	mutex_unlock(&sit_i->sentry_lock);
	return ret ? GC_OK : GC_NEXT;
}

/*
 * This function compares node address got in summary with that in NAT.
 * On validity, copy that node with cold status, otherwise (invalid node)
 * ignore that.
 */
static int gc_node_segment(struct f2fs_sb_info *sbi,
		struct f2fs_summary *sum, unsigned int segno, int gc_type)
{
	bool initial = true;
	struct f2fs_summary *entry;
	int off;

next_step:
	entry = sum;
	for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
		nid_t nid = le32_to_cpu(entry->nid);
		struct page *node_page;
		int err;

		/*
		 * It makes sure that free segments are able to write
		 * all the dirty node pages before CP after this CP.
		 * So let's check the space of dirty node pages.
		 */
		if (should_do_checkpoint(sbi)) {
			mutex_lock(&sbi->cp_mutex);
			block_operations(sbi);
			return GC_BLOCKED;
		}

		err = check_valid_map(sbi, segno, off);
		if (err == GC_NEXT)
			continue;

		if (initial) {
			ra_node_page(sbi, nid);
			continue;
		}
		node_page = get_node_page(sbi, nid);
		if (IS_ERR(node_page))
			continue;

		/* set page dirty and write it */
		if (!PageWriteback(node_page))
			set_page_dirty(node_page);
		f2fs_put_page(node_page, 1);
		stat_inc_node_blk_count(sbi, 1);
	}
	if (initial) {
		initial = false;
		goto next_step;
	}

	if (gc_type == FG_GC) {
		struct writeback_control wbc = {
			.sync_mode = WB_SYNC_ALL,
			.nr_to_write = LONG_MAX,
			.for_reclaim = 0,
		};
		sync_node_pages(sbi, 0, &wbc);
	}
	return GC_DONE;
}

/*
 * Calculate start block index that this node page contains
 */
block_t start_bidx_of_node(unsigned int node_ofs)
{
	unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
	unsigned int bidx;

	if (node_ofs == 0)
		return 0;

	if (node_ofs <= 2) {
		bidx = node_ofs - 1;
	} else if (node_ofs <= indirect_blks) {
		int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
		bidx = node_ofs - 2 - dec;
	} else {
		int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
		bidx = node_ofs - 5 - dec;
	}
	return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE;
}

static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
		struct node_info *dni, block_t blkaddr, unsigned int *nofs)
{
	struct page *node_page;
	nid_t nid;
	unsigned int ofs_in_node;
	block_t source_blkaddr;

	nid = le32_to_cpu(sum->nid);
	ofs_in_node = le16_to_cpu(sum->ofs_in_node);

	node_page = get_node_page(sbi, nid);
	if (IS_ERR(node_page))
		return GC_NEXT;

	get_node_info(sbi, nid, dni);

	if (sum->version != dni->version) {
		f2fs_put_page(node_page, 1);
		return GC_NEXT;
	}

	*nofs = ofs_of_node(node_page);
	source_blkaddr = datablock_addr(node_page, ofs_in_node);
	f2fs_put_page(node_page, 1);

	if (source_blkaddr != blkaddr)
		return GC_NEXT;
	return GC_OK;
}

static void move_data_page(struct inode *inode, struct page *page, int gc_type)
{
	if (page->mapping != inode->i_mapping)
		goto out;

	if (inode != page->mapping->host)
		goto out;

	if (PageWriteback(page))
		goto out;

	if (gc_type == BG_GC) {
		set_page_dirty(page);
		set_cold_data(page);
	} else {
		struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
		mutex_lock_op(sbi, DATA_WRITE);
		if (clear_page_dirty_for_io(page) &&
			S_ISDIR(inode->i_mode)) {
			dec_page_count(sbi, F2FS_DIRTY_DENTS);
			inode_dec_dirty_dents(inode);
		}
		set_cold_data(page);
		do_write_data_page(page);
		mutex_unlock_op(sbi, DATA_WRITE);
		clear_cold_data(page);
	}
out:
	f2fs_put_page(page, 1);
}

/*
 * This function tries to get parent node of victim data block, and identifies
 * data block validity. If the block is valid, copy that with cold status and
 * modify parent node.
 * If the parent node is not valid or the data block address is different,
 * the victim data block is ignored.
 */
static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
		struct list_head *ilist, unsigned int segno, int gc_type)
{
	struct super_block *sb = sbi->sb;
	struct f2fs_summary *entry;
	block_t start_addr;
	int err, off;
	int phase = 0;

	start_addr = START_BLOCK(sbi, segno);

next_step:
	entry = sum;
	for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
		struct page *data_page;
		struct inode *inode;
		struct node_info dni; /* dnode info for the data */
		unsigned int ofs_in_node, nofs;
		block_t start_bidx;

		/*
		 * It makes sure that free segments are able to write
		 * all the dirty node pages before CP after this CP.
		 * So let's check the space of dirty node pages.
		 */
		if (should_do_checkpoint(sbi)) {
			mutex_lock(&sbi->cp_mutex);
			block_operations(sbi);
			err = GC_BLOCKED;
			goto stop;
		}

		err = check_valid_map(sbi, segno, off);
		if (err == GC_NEXT)
			continue;

		if (phase == 0) {
			ra_node_page(sbi, le32_to_cpu(entry->nid));
			continue;
		}

		/* Get an inode by ino with checking validity */
		err = check_dnode(sbi, entry, &dni, start_addr + off, &nofs);
		if (err == GC_NEXT)
			continue;

		if (phase == 1) {
			ra_node_page(sbi, dni.ino);
			continue;
		}

		start_bidx = start_bidx_of_node(nofs);
		ofs_in_node = le16_to_cpu(entry->ofs_in_node);

		if (phase == 2) {
			inode = f2fs_iget_nowait(sb, dni.ino);
			if (IS_ERR(inode))
				continue;

			data_page = find_data_page(inode,
					start_bidx + ofs_in_node);
			if (IS_ERR(data_page))
				goto next_iput;

			f2fs_put_page(data_page, 0);
			add_gc_inode(inode, ilist);
		} else {
			inode = find_gc_inode(dni.ino, ilist);
			if (inode) {
				data_page = get_lock_data_page(inode,
						start_bidx + ofs_in_node);
				if (IS_ERR(data_page))
					continue;
				move_data_page(inode, data_page, gc_type);
				stat_inc_data_blk_count(sbi, 1);
			}
		}
		continue;
next_iput:
		iput(inode);
	}
	if (++phase < 4)
		goto next_step;
	err = GC_DONE;
stop:
	if (gc_type == FG_GC)
		f2fs_submit_bio(sbi, DATA, true);
	return err;
}

static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
						int gc_type, int type)
{
	struct sit_info *sit_i = SIT_I(sbi);
	int ret;
	mutex_lock(&sit_i->sentry_lock);
	ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS);
	mutex_unlock(&sit_i->sentry_lock);
	return ret;
}

static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
				struct list_head *ilist, int gc_type)
{
	struct page *sum_page;
	struct f2fs_summary_block *sum;
	int ret = GC_DONE;

	/* read segment summary of victim */
	sum_page = get_sum_page(sbi, segno);
	if (IS_ERR(sum_page))
		return GC_ERROR;

	/*
	 * CP needs to lock sum_page. In this time, we don't need
	 * to lock this page, because this summary page is not gone anywhere.
	 * Also, this page is not gonna be updated before GC is done.
	 */
	unlock_page(sum_page);
	sum = page_address(sum_page);

	switch (GET_SUM_TYPE((&sum->footer))) {
	case SUM_TYPE_NODE:
		ret = gc_node_segment(sbi, sum->entries, segno, gc_type);
		break;
	case SUM_TYPE_DATA:
		ret = gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
		break;
	}
	stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
	stat_inc_call_count(sbi->stat_info);

	f2fs_put_page(sum_page, 0);
	return ret;
}

int f2fs_gc(struct f2fs_sb_info *sbi, int nGC)
{
	unsigned int segno;
	int old_free_secs, cur_free_secs;
	int gc_status, nfree;
	struct list_head ilist;
	int gc_type = BG_GC;

	INIT_LIST_HEAD(&ilist);
gc_more:
	nfree = 0;
	gc_status = GC_NONE;

	if (has_not_enough_free_secs(sbi))
		old_free_secs = reserved_sections(sbi);
	else
		old_free_secs = free_sections(sbi);

	while (sbi->sb->s_flags & MS_ACTIVE) {
		int i;
		if (has_not_enough_free_secs(sbi))
			gc_type = FG_GC;

		cur_free_secs = free_sections(sbi) + nfree;

		/* We got free space successfully. */
		if (nGC < cur_free_secs - old_free_secs)
			break;

		if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
			break;

		for (i = 0; i < sbi->segs_per_sec; i++) {
			/*
			 * do_garbage_collect will give us three gc_status:
			 * GC_ERROR, GC_DONE, and GC_BLOCKED.
			 * If GC is finished uncleanly, we have to return
			 * the victim to dirty segment list.
			 */
			gc_status = do_garbage_collect(sbi, segno + i,
					&ilist, gc_type);
			if (gc_status != GC_DONE)
				goto stop;
			nfree++;
		}
	}
stop:
	if (has_not_enough_free_secs(sbi) || gc_status == GC_BLOCKED) {
		write_checkpoint(sbi, (gc_status == GC_BLOCKED), false);
		if (nfree)
			goto gc_more;
	}
	mutex_unlock(&sbi->gc_mutex);

	put_gc_inode(&ilist);
	BUG_ON(!list_empty(&ilist));
	return gc_status;
}

void build_gc_manager(struct f2fs_sb_info *sbi)
{
	DIRTY_I(sbi)->v_ops = &default_v_ops;
}

int create_gc_caches(void)
{
	winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes",
			sizeof(struct inode_entry), NULL);
	if (!winode_slab)
		return -ENOMEM;
	return 0;
}

void destroy_gc_caches(void)
{
	kmem_cache_destroy(winode_slab);
}