text: /*
   * 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/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"
  #include <trace/events/f2fs.h>
  
  static struct kmem_cache *winode_slab;
  
  static int gc_thread_func(void *data)
  {
  	struct f2fs_sb_info *sbi = data;
  	struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
  	wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
  	long wait_ms;
  
  	wait_ms = gc_th->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;
  
  		if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
  			wait_ms = increase_sleep_time(gc_th, wait_ms);
  			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(gc_th, wait_ms);
  			mutex_unlock(&sbi->gc_mutex);
  			continue;
  		}
  
  		if (has_enough_invalid_blocks(sbi))
  			wait_ms = decrease_sleep_time(gc_th, wait_ms);
  		else
  			wait_ms = increase_sleep_time(gc_th, wait_ms);
  
  		stat_inc_bggc_count(sbi);
  
  		/* if return value is not zero, no victim was selected */
  		if (f2fs_gc(sbi))
  			wait_ms = gc_th->no_gc_sleep_time;
  
  		/* balancing f2fs's metadata periodically */
  		f2fs_balance_fs_bg(sbi);
  
  	} while (!kthread_should_stop());
  	return 0;
  }
  
  int start_gc_thread(struct f2fs_sb_info *sbi)
  {
  	struct f2fs_gc_kthread *gc_th;
  	dev_t dev = sbi->sb->s_bdev->bd_dev;
  	int err = 0;
  
  	if (!test_opt(sbi, BG_GC))
  		goto out;
  	gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
  	if (!gc_th) {
  		err = -ENOMEM;
  		goto out;
  	}
  
  	gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME;
  	gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
  	gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
  
  	gc_th->gc_idle = 0;
  
  	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,
  			"f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
  	if (IS_ERR(gc_th->f2fs_gc_task)) {
  		err = PTR_ERR(gc_th->f2fs_gc_task);
  		kfree(gc_th);
  		sbi->gc_thread = NULL;
  	}
  
  out:
  	return err;
  }
  
  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(struct f2fs_gc_kthread *gc_th, int gc_type)
  {
  	int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
  
  	if (gc_th && gc_th->gc_idle) {
  		if (gc_th->gc_idle == 1)
  			gc_mode = GC_CB;
  		else if (gc_th->gc_idle == 2)
  			gc_mode = GC_GREEDY;
  	}
  	return gc_mode;
  }
  
  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 == SSR) {
  		p->gc_mode = GC_GREEDY;
  		p->dirty_segmap = dirty_i->dirty_segmap[type];
  		p->max_search = dirty_i->nr_dirty[type];
  		p->ofs_unit = 1;
  	} else {
  		p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
  		p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
  		p->max_search = dirty_i->nr_dirty[DIRTY];
  		p->ofs_unit = sbi->segs_per_sec;
  	}
  
  	if (p->max_search > MAX_VICTIM_SEARCH)
  		p->max_search = MAX_VICTIM_SEARCH;
  
  	p->offset = sbi->last_victim[p->gc_mode];
  }
  
  static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
  				struct victim_sel_policy *p)
  {
  	/* SSR allocates in a segment unit */
  	if (p->alloc_mode == SSR)
  		return 1 << sbi->log_blocks_per_seg;
  	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 hint = 0;
  	unsigned int secno;
  
  	/*
  	 * 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.
  	 */
  next:
  	secno = find_next_bit(dirty_i->victim_secmap, TOTAL_SECS(sbi), hint++);
  	if (secno < TOTAL_SECS(sbi)) {
  		if (sec_usage_check(sbi, secno))
  			goto next;
  		clear_bit(secno, dirty_i->victim_secmap);
  		return secno * sbi->segs_per_sec;
  	}
  	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 inline 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 paths.
   * 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 secno, max_cost;
  	int nsearched = 0;
  
  	p.alloc_mode = alloc_mode;
  	select_policy(sbi, gc_type, type, &p);
  
  	p.min_segno = NULL_SEGNO;
  	p.min_cost = max_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;
  		unsigned int segno;
  
  		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;
  		if (p.ofs_unit > 1)
  			p.offset -= segno % p.ofs_unit;
  
  		secno = GET_SECNO(sbi, segno);
  
  		if (sec_usage_check(sbi, secno))
  			continue;
  		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
  			continue;
  
  		cost = get_gc_cost(sbi, segno, &p);
  
  		if (p.min_cost > cost) {
  			p.min_segno = segno;
  			p.min_cost = cost;
  		} else if (unlikely(cost == max_cost)) {
  			continue;
  		}
  
  		if (nsearched++ >= p.max_search) {
  			sbi->last_victim[p.gc_mode] = segno;
  			break;
  		}
  	}
  	if (p.min_segno != NULL_SEGNO) {
  got_it:
  		if (p.alloc_mode == LFS) {
  			secno = GET_SECNO(sbi, p.min_segno);
  			if (gc_type == FG_GC)
  				sbi->cur_victim_sec = secno;
  			else
  				set_bit(secno, dirty_i->victim_secmap);
  		}
  		*result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
  
  		trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
  				sbi->cur_victim_sec,
  				prefree_segments(sbi), free_segments(sbi));
  	}
  	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 inode_entry *ie;
  
  	list_for_each_entry(ie, ilist, 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 inode_entry *new_ie;
  
  	if (inode == find_gc_inode(inode->i_ino, ilist)) {
  		iput(inode);
  		return;
  	}
  
  	new_ie = f2fs_kmem_cache_alloc(winode_slab, GFP_NOFS);
  	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;
  }
  
  /*
   * 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 void 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;
  
  		/* stop BG_GC if there is not enough free sections. */
  		if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
  			return;
  
  		if (check_valid_map(sbi, segno, off) == 0)
  			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 (gc_type == FG_GC) {
  			f2fs_wait_on_page_writeback(node_page, NODE, true);
  			set_page_dirty(node_page);
  		} else {
  			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);
  
  		/*
  		 * In the case of FG_GC, it'd be better to reclaim this victim
  		 * completely.
  		 */
  		if (get_valid_blocks(sbi, segno, 1) != 0)
  			goto next_step;
  	}
  }
  
  /*
   * Calculate start block index indicating the given node offset.
   * Be careful, caller should give this node offset only indicating direct node
   * blocks. If any node offsets, which point the other types of node blocks such
   * as indirect or double indirect node blocks, are given, it must be a caller's
   * bug.
   */
  block_t start_bidx_of_node(unsigned int node_ofs, struct f2fs_inode_info *fi)
  {
  	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(fi);
  }
  
  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 0;
  
  	get_node_info(sbi, nid, dni);
  
  	if (sum->version != dni->version) {
  		f2fs_put_page(node_page, 1);
  		return 0;
  	}
  
  	*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 0;
  	return 1;
  }
  
  static void move_data_page(struct inode *inode, struct page *page, int gc_type)
  {
  	if (gc_type == BG_GC) {
  		if (PageWriteback(page))
  			goto out;
  		set_page_dirty(page);
  		set_cold_data(page);
  	} else {
  		struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
  
  		f2fs_wait_on_page_writeback(page, DATA, true);
  
  		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);
  		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 void 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 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;
  
  		/* stop BG_GC if there is not enough free sections. */
  		if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
  			return;
  
  		if (check_valid_map(sbi, segno, off) == 0)
  			continue;
  
  		if (phase == 0) {
  			ra_node_page(sbi, le32_to_cpu(entry->nid));
  			continue;
  		}
  
  		/* Get an inode by ino with checking validity */
  		if (check_dnode(sbi, entry, &dni, start_addr + off, &nofs) == 0)
  			continue;
  
  		if (phase == 1) {
  			ra_node_page(sbi, dni.ino);
  			continue;
  		}
  
  		ofs_in_node = le16_to_cpu(entry->ofs_in_node);
  
  		if (phase == 2) {
  			inode = f2fs_iget(sb, dni.ino);
  			if (IS_ERR(inode))
  				continue;
  
  			start_bidx = start_bidx_of_node(nofs, F2FS_I(inode));
  
  			data_page = find_data_page(inode,
  					start_bidx + ofs_in_node, false);
  			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) {
  				start_bidx = start_bidx_of_node(nofs,
  								F2FS_I(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;
  
  	if (gc_type == FG_GC) {
  		f2fs_submit_bio(sbi, DATA, true);
  
  		/*
  		 * In the case of FG_GC, it'd be better to reclaim this victim
  		 * completely.
  		 */
  		if (get_valid_blocks(sbi, segno, 1) != 0) {
  			phase = 2;
  			goto next_step;
  		}
  	}
  }
  
  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 void 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;
  	struct blk_plug plug;
  
  	/* read segment summary of victim */
  	sum_page = get_sum_page(sbi, segno);
  	if (IS_ERR(sum_page))
  		return;
  
  	blk_start_plug(&plug);
  
  	sum = page_address(sum_page);
  
  	switch (GET_SUM_TYPE((&sum->footer))) {
  	case SUM_TYPE_NODE:
  		gc_node_segment(sbi, sum->entries, segno, gc_type);
  		break;
  	case SUM_TYPE_DATA:
  		gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
  		break;
  	}
  	blk_finish_plug(&plug);
  
  	stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
  	stat_inc_call_count(sbi->stat_info);
  
  	f2fs_put_page(sum_page, 1);
  }
  
  int f2fs_gc(struct f2fs_sb_info *sbi)
  {
  	struct list_head ilist;
  	unsigned int segno, i;
  	int gc_type = BG_GC;
  	int nfree = 0;
  	int ret = -1;
  
  	INIT_LIST_HEAD(&ilist);
  gc_more:
  	if (!(sbi->sb->s_flags & MS_ACTIVE))
  		goto stop;
  
  	if (gc_type == BG_GC && has_not_enough_free_secs(sbi, nfree)) {
  		gc_type = FG_GC;
  		write_checkpoint(sbi, false);
  	}
  
  	if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
  		goto stop;
  	ret = 0;
  
  	for (i = 0; i < sbi->segs_per_sec; i++)
  		do_garbage_collect(sbi, segno + i, &ilist, gc_type);
  
  	if (gc_type == FG_GC) {
  		sbi->cur_victim_sec = NULL_SEGNO;
  		nfree++;
  		WARN_ON(get_valid_blocks(sbi, segno, sbi->segs_per_sec));
  	}
  
  	if (has_not_enough_free_secs(sbi, nfree))
  		goto gc_more;
  
  	if (gc_type == FG_GC)
  		write_checkpoint(sbi, false);
  stop:
  	mutex_unlock(&sbi->gc_mutex);
  
  	put_gc_inode(&ilist);
  	return ret;
  }
  
  void build_gc_manager(struct f2fs_sb_info *sbi)
  {
  	DIRTY_I(sbi)->v_ops = &default_v_ops;
  }
  
  int __init 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);
  }
  