// SPDX-License-Identifier: GPL-2.0
/*
 * f2fs extent cache support
 *
 * Copyright (c) 2015 Motorola Mobility
 * Copyright (c) 2015 Samsung Electronics
 * Authors: Jaegeuk Kim <jaegeuk@kernel.org>
 *          Chao Yu <chao2.yu@samsung.com>
 */

#include <linux/fs.h>
#include <linux/f2fs_fs.h>

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

bool sanity_check_extent_cache(struct inode *inode)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct f2fs_inode_info *fi = F2FS_I(inode);
	struct extent_info *ei;

	if (!fi->extent_tree[EX_READ])
		return true;

	ei = &fi->extent_tree[EX_READ]->largest;

	if (ei->len &&
		(!f2fs_is_valid_blkaddr(sbi, ei->blk,
					DATA_GENERIC_ENHANCE) ||
		!f2fs_is_valid_blkaddr(sbi, ei->blk + ei->len - 1,
					DATA_GENERIC_ENHANCE))) {
		set_sbi_flag(sbi, SBI_NEED_FSCK);
		f2fs_warn(sbi, "%s: inode (ino=%lx) extent info [%u, %u, %u] is incorrect, run fsck to fix",
			  __func__, inode->i_ino,
			  ei->blk, ei->fofs, ei->len);
		return false;
	}
	return true;
}

static void __set_extent_info(struct extent_info *ei,
				unsigned int fofs, unsigned int len,
				block_t blk, bool keep_clen,
				enum extent_type type)
{
	ei->fofs = fofs;
	ei->len = len;

	if (type == EX_READ) {
		ei->blk = blk;
		if (keep_clen)
			return;
#ifdef CONFIG_F2FS_FS_COMPRESSION
		ei->c_len = 0;
#endif
	}
}

static bool __may_read_extent_tree(struct inode *inode)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

	if (!test_opt(sbi, READ_EXTENT_CACHE))
		return false;
	if (is_inode_flag_set(inode, FI_NO_EXTENT))
		return false;
	if (is_inode_flag_set(inode, FI_COMPRESSED_FILE) &&
			 !f2fs_sb_has_readonly(sbi))
		return false;
	return S_ISREG(inode->i_mode);
}

static bool __init_may_extent_tree(struct inode *inode, enum extent_type type)
{
	if (type == EX_READ)
		return __may_read_extent_tree(inode);
	return false;
}

static bool __may_extent_tree(struct inode *inode, enum extent_type type)
{
	/*
	 * for recovered files during mount do not create extents
	 * if shrinker is not registered.
	 */
	if (list_empty(&F2FS_I_SB(inode)->s_list))
		return false;

	return __init_may_extent_tree(inode, type);
}

static void __try_update_largest_extent(struct extent_tree *et,
						struct extent_node *en)
{
	if (et->type != EX_READ)
		return;
	if (en->ei.len <= et->largest.len)
		return;

	et->largest = en->ei;
	et->largest_updated = true;
}

static bool __is_extent_mergeable(struct extent_info *back,
		struct extent_info *front, enum extent_type type)
{
	if (type == EX_READ) {
#ifdef CONFIG_F2FS_FS_COMPRESSION
		if (back->c_len && back->len != back->c_len)
			return false;
		if (front->c_len && front->len != front->c_len)
			return false;
#endif
		return (back->fofs + back->len == front->fofs &&
				back->blk + back->len == front->blk);
	}
	return false;
}

static bool __is_back_mergeable(struct extent_info *cur,
		struct extent_info *back, enum extent_type type)
{
	return __is_extent_mergeable(back, cur, type);
}

static bool __is_front_mergeable(struct extent_info *cur,
		struct extent_info *front, enum extent_type type)
{
	return __is_extent_mergeable(cur, front, type);
}

static struct rb_entry *__lookup_rb_tree_fast(struct rb_entry *cached_re,
							unsigned int ofs)
{
	if (cached_re) {
		if (cached_re->ofs <= ofs &&
				cached_re->ofs + cached_re->len > ofs) {
			return cached_re;
		}
	}
	return NULL;
}

static struct rb_entry *__lookup_rb_tree_slow(struct rb_root_cached *root,
							unsigned int ofs)
{
	struct rb_node *node = root->rb_root.rb_node;
	struct rb_entry *re;

	while (node) {
		re = rb_entry(node, struct rb_entry, rb_node);

		if (ofs < re->ofs)
			node = node->rb_left;
		else if (ofs >= re->ofs + re->len)
			node = node->rb_right;
		else
			return re;
	}
	return NULL;
}

struct rb_entry *f2fs_lookup_rb_tree(struct rb_root_cached *root,
				struct rb_entry *cached_re, unsigned int ofs)
{
	struct rb_entry *re;

	re = __lookup_rb_tree_fast(cached_re, ofs);
	if (!re)
		return __lookup_rb_tree_slow(root, ofs);

	return re;
}

struct rb_node **f2fs_lookup_rb_tree_for_insert(struct f2fs_sb_info *sbi,
				struct rb_root_cached *root,
				struct rb_node **parent,
				unsigned int ofs, bool *leftmost)
{
	struct rb_node **p = &root->rb_root.rb_node;
	struct rb_entry *re;

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

		if (ofs < re->ofs) {
			p = &(*p)->rb_left;
		} else if (ofs >= re->ofs + re->len) {
			p = &(*p)->rb_right;
			*leftmost = false;
		} else {
			f2fs_bug_on(sbi, 1);
		}
	}

	return p;
}

/*
 * lookup rb entry in position of @ofs in rb-tree,
 * if hit, return the entry, otherwise, return NULL
 * @prev_ex: extent before ofs
 * @next_ex: extent after ofs
 * @insert_p: insert point for new extent at ofs
 * in order to simplify the insertion after.
 * tree must stay unchanged between lookup and insertion.
 */
struct rb_entry *f2fs_lookup_rb_tree_ret(struct rb_root_cached *root,
				struct rb_entry *cached_re,
				unsigned int ofs,
				struct rb_entry **prev_entry,
				struct rb_entry **next_entry,
				struct rb_node ***insert_p,
				struct rb_node **insert_parent,
				bool force, bool *leftmost)
{
	struct rb_node **pnode = &root->rb_root.rb_node;
	struct rb_node *parent = NULL, *tmp_node;
	struct rb_entry *re = cached_re;

	*insert_p = NULL;
	*insert_parent = NULL;
	*prev_entry = NULL;
	*next_entry = NULL;

	if (RB_EMPTY_ROOT(&root->rb_root))
		return NULL;

	if (re) {
		if (re->ofs <= ofs && re->ofs + re->len > ofs)
			goto lookup_neighbors;
	}

	if (leftmost)
		*leftmost = true;

	while (*pnode) {
		parent = *pnode;
		re = rb_entry(*pnode, struct rb_entry, rb_node);

		if (ofs < re->ofs) {
			pnode = &(*pnode)->rb_left;
		} else if (ofs >= re->ofs + re->len) {
			pnode = &(*pnode)->rb_right;
			if (leftmost)
				*leftmost = false;
		} else {
			goto lookup_neighbors;
		}
	}

	*insert_p = pnode;
	*insert_parent = parent;

	re = rb_entry(parent, struct rb_entry, rb_node);
	tmp_node = parent;
	if (parent && ofs > re->ofs)
		tmp_node = rb_next(parent);
	*next_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);

	tmp_node = parent;
	if (parent && ofs < re->ofs)
		tmp_node = rb_prev(parent);
	*prev_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
	return NULL;

lookup_neighbors:
	if (ofs == re->ofs || force) {
		/* lookup prev node for merging backward later */
		tmp_node = rb_prev(&re->rb_node);
		*prev_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
	}
	if (ofs == re->ofs + re->len - 1 || force) {
		/* lookup next node for merging frontward later */
		tmp_node = rb_next(&re->rb_node);
		*next_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
	}
	return re;
}

bool f2fs_check_rb_tree_consistence(struct f2fs_sb_info *sbi,
				struct rb_root_cached *root)
{
#ifdef CONFIG_F2FS_CHECK_FS
	struct rb_node *cur = rb_first_cached(root), *next;
	struct rb_entry *cur_re, *next_re;

	if (!cur)
		return true;

	while (cur) {
		next = rb_next(cur);
		if (!next)
			return true;

		cur_re = rb_entry(cur, struct rb_entry, rb_node);
		next_re = rb_entry(next, struct rb_entry, rb_node);

		if (cur_re->ofs + cur_re->len > next_re->ofs) {
			f2fs_info(sbi, "inconsistent rbtree, cur(%u, %u) next(%u, %u)",
				  cur_re->ofs, cur_re->len,
				  next_re->ofs, next_re->len);
			return false;
		}
		cur = next;
	}
#endif
	return true;
}

static struct kmem_cache *extent_tree_slab;
static struct kmem_cache *extent_node_slab;

static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
				struct extent_tree *et, struct extent_info *ei,
				struct rb_node *parent, struct rb_node **p,
				bool leftmost)
{
	struct extent_tree_info *eti = &sbi->extent_tree[et->type];
	struct extent_node *en;

	en = f2fs_kmem_cache_alloc(extent_node_slab, GFP_ATOMIC, false, sbi);
	if (!en)
		return NULL;

	en->ei = *ei;
	INIT_LIST_HEAD(&en->list);
	en->et = et;

	rb_link_node(&en->rb_node, parent, p);
	rb_insert_color_cached(&en->rb_node, &et->root, leftmost);
	atomic_inc(&et->node_cnt);
	atomic_inc(&eti->total_ext_node);
	return en;
}

static void __detach_extent_node(struct f2fs_sb_info *sbi,
				struct extent_tree *et, struct extent_node *en)
{
	struct extent_tree_info *eti = &sbi->extent_tree[et->type];

	rb_erase_cached(&en->rb_node, &et->root);
	atomic_dec(&et->node_cnt);
	atomic_dec(&eti->total_ext_node);

	if (et->cached_en == en)
		et->cached_en = NULL;
	kmem_cache_free(extent_node_slab, en);
}

/*
 * Flow to release an extent_node:
 * 1. list_del_init
 * 2. __detach_extent_node
 * 3. kmem_cache_free.
 */
static void __release_extent_node(struct f2fs_sb_info *sbi,
			struct extent_tree *et, struct extent_node *en)
{
	struct extent_tree_info *eti = &sbi->extent_tree[et->type];

	spin_lock(&eti->extent_lock);
	f2fs_bug_on(sbi, list_empty(&en->list));
	list_del_init(&en->list);
	spin_unlock(&eti->extent_lock);

	__detach_extent_node(sbi, et, en);
}

static struct extent_tree *__grab_extent_tree(struct inode *inode,
						enum extent_type type)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree_info *eti = &sbi->extent_tree[type];
	struct extent_tree *et;
	nid_t ino = inode->i_ino;

	mutex_lock(&eti->extent_tree_lock);
	et = radix_tree_lookup(&eti->extent_tree_root, ino);
	if (!et) {
		et = f2fs_kmem_cache_alloc(extent_tree_slab,
					GFP_NOFS, true, NULL);
		f2fs_radix_tree_insert(&eti->extent_tree_root, ino, et);
		memset(et, 0, sizeof(struct extent_tree));
		et->ino = ino;
		et->type = type;
		et->root = RB_ROOT_CACHED;
		et->cached_en = NULL;
		rwlock_init(&et->lock);
		INIT_LIST_HEAD(&et->list);
		atomic_set(&et->node_cnt, 0);
		atomic_inc(&eti->total_ext_tree);
	} else {
		atomic_dec(&eti->total_zombie_tree);
		list_del_init(&et->list);
	}
	mutex_unlock(&eti->extent_tree_lock);

	/* never died until evict_inode */
	F2FS_I(inode)->extent_tree[type] = et;

	return et;
}

static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
					struct extent_tree *et)
{
	struct rb_node *node, *next;
	struct extent_node *en;
	unsigned int count = atomic_read(&et->node_cnt);

	node = rb_first_cached(&et->root);
	while (node) {
		next = rb_next(node);
		en = rb_entry(node, struct extent_node, rb_node);
		__release_extent_node(sbi, et, en);
		node = next;
	}

	return count - atomic_read(&et->node_cnt);
}

static void __drop_largest_extent(struct extent_tree *et,
					pgoff_t fofs, unsigned int len)
{
	if (fofs < (pgoff_t)et->largest.fofs + et->largest.len &&
			fofs + len > et->largest.fofs) {
		et->largest.len = 0;
		et->largest_updated = true;
	}
}

void f2fs_init_read_extent_tree(struct inode *inode, struct page *ipage)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree_info *eti = &sbi->extent_tree[EX_READ];
	struct f2fs_extent *i_ext = &F2FS_INODE(ipage)->i_ext;
	struct extent_tree *et;
	struct extent_node *en;
	struct extent_info ei;

	if (!__may_extent_tree(inode, EX_READ)) {
		/* drop largest read extent */
		if (i_ext && i_ext->len) {
			f2fs_wait_on_page_writeback(ipage, NODE, true, true);
			i_ext->len = 0;
			set_page_dirty(ipage);
		}
		goto out;
	}

	et = __grab_extent_tree(inode, EX_READ);

	if (!i_ext || !i_ext->len)
		goto out;

	get_read_extent_info(&ei, i_ext);

	write_lock(&et->lock);
	if (atomic_read(&et->node_cnt))
		goto unlock_out;

	en = __attach_extent_node(sbi, et, &ei, NULL,
				&et->root.rb_root.rb_node, true);
	if (en) {
		et->largest = en->ei;
		et->cached_en = en;

		spin_lock(&eti->extent_lock);
		list_add_tail(&en->list, &eti->extent_list);
		spin_unlock(&eti->extent_lock);
	}
unlock_out:
	write_unlock(&et->lock);
out:
	if (!F2FS_I(inode)->extent_tree[EX_READ])
		set_inode_flag(inode, FI_NO_EXTENT);
}

void f2fs_init_extent_tree(struct inode *inode)
{
	/* initialize read cache */
	if (__init_may_extent_tree(inode, EX_READ))
		__grab_extent_tree(inode, EX_READ);
}

static bool __lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
			struct extent_info *ei, enum extent_type type)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree_info *eti = &sbi->extent_tree[type];
	struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
	struct extent_node *en;
	bool ret = false;

	if (!et)
		return false;

	trace_f2fs_lookup_extent_tree_start(inode, pgofs, type);

	read_lock(&et->lock);

	if (type == EX_READ &&
			et->largest.fofs <= pgofs &&
			(pgoff_t)et->largest.fofs + et->largest.len > pgofs) {
		*ei = et->largest;
		ret = true;
		stat_inc_largest_node_hit(sbi);
		goto out;
	}

	en = (struct extent_node *)f2fs_lookup_rb_tree(&et->root,
				(struct rb_entry *)et->cached_en, pgofs);
	if (!en)
		goto out;

	if (en == et->cached_en)
		stat_inc_cached_node_hit(sbi, type);
	else
		stat_inc_rbtree_node_hit(sbi, type);

	*ei = en->ei;
	spin_lock(&eti->extent_lock);
	if (!list_empty(&en->list)) {
		list_move_tail(&en->list, &eti->extent_list);
		et->cached_en = en;
	}
	spin_unlock(&eti->extent_lock);
	ret = true;
out:
	stat_inc_total_hit(sbi, type);
	read_unlock(&et->lock);

	if (type == EX_READ)
		trace_f2fs_lookup_read_extent_tree_end(inode, pgofs, ei);
	return ret;
}

static struct extent_node *__try_merge_extent_node(struct f2fs_sb_info *sbi,
				struct extent_tree *et, struct extent_info *ei,
				struct extent_node *prev_ex,
				struct extent_node *next_ex)
{
	struct extent_tree_info *eti = &sbi->extent_tree[et->type];
	struct extent_node *en = NULL;

	if (prev_ex && __is_back_mergeable(ei, &prev_ex->ei, et->type)) {
		prev_ex->ei.len += ei->len;
		ei = &prev_ex->ei;
		en = prev_ex;
	}

	if (next_ex && __is_front_mergeable(ei, &next_ex->ei, et->type)) {
		next_ex->ei.fofs = ei->fofs;
		next_ex->ei.len += ei->len;
		if (et->type == EX_READ)
			next_ex->ei.blk = ei->blk;
		if (en)
			__release_extent_node(sbi, et, prev_ex);

		en = next_ex;
	}

	if (!en)
		return NULL;

	__try_update_largest_extent(et, en);

	spin_lock(&eti->extent_lock);
	if (!list_empty(&en->list)) {
		list_move_tail(&en->list, &eti->extent_list);
		et->cached_en = en;
	}
	spin_unlock(&eti->extent_lock);
	return en;
}

static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
				struct extent_tree *et, struct extent_info *ei,
				struct rb_node **insert_p,
				struct rb_node *insert_parent,
				bool leftmost)
{
	struct extent_tree_info *eti = &sbi->extent_tree[et->type];
	struct rb_node **p;
	struct rb_node *parent = NULL;
	struct extent_node *en = NULL;

	if (insert_p && insert_parent) {
		parent = insert_parent;
		p = insert_p;
		goto do_insert;
	}

	leftmost = true;

	p = f2fs_lookup_rb_tree_for_insert(sbi, &et->root, &parent,
						ei->fofs, &leftmost);
do_insert:
	en = __attach_extent_node(sbi, et, ei, parent, p, leftmost);
	if (!en)
		return NULL;

	__try_update_largest_extent(et, en);

	/* update in global extent list */
	spin_lock(&eti->extent_lock);
	list_add_tail(&en->list, &eti->extent_list);
	et->cached_en = en;
	spin_unlock(&eti->extent_lock);
	return en;
}

static void __update_extent_tree_range(struct inode *inode,
			struct extent_info *tei, enum extent_type type)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
	struct extent_node *en = NULL, *en1 = NULL;
	struct extent_node *prev_en = NULL, *next_en = NULL;
	struct extent_info ei, dei, prev;
	struct rb_node **insert_p = NULL, *insert_parent = NULL;
	unsigned int fofs = tei->fofs, len = tei->len;
	unsigned int end = fofs + len;
	bool updated = false;
	bool leftmost = false;

	if (!et)
		return;

	if (type == EX_READ)
		trace_f2fs_update_read_extent_tree_range(inode, fofs, len,
						tei->blk, 0);
	write_lock(&et->lock);

	if (type == EX_READ) {
		if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
			write_unlock(&et->lock);
			return;
		}

		prev = et->largest;
		dei.len = 0;

		/*
		 * drop largest extent before lookup, in case it's already
		 * been shrunk from extent tree
		 */
		__drop_largest_extent(et, fofs, len);
	}

	/* 1. lookup first extent node in range [fofs, fofs + len - 1] */
	en = (struct extent_node *)f2fs_lookup_rb_tree_ret(&et->root,
					(struct rb_entry *)et->cached_en, fofs,
					(struct rb_entry **)&prev_en,
					(struct rb_entry **)&next_en,
					&insert_p, &insert_parent, false,
					&leftmost);
	if (!en)
		en = next_en;

	/* 2. invalidate all extent nodes in range [fofs, fofs + len - 1] */
	while (en && en->ei.fofs < end) {
		unsigned int org_end;
		int parts = 0;	/* # of parts current extent split into */

		next_en = en1 = NULL;

		dei = en->ei;
		org_end = dei.fofs + dei.len;
		f2fs_bug_on(sbi, fofs >= org_end);

		if (fofs > dei.fofs && (type != EX_READ ||
				fofs - dei.fofs >= F2FS_MIN_EXTENT_LEN)) {
			en->ei.len = fofs - en->ei.fofs;
			prev_en = en;
			parts = 1;
		}

		if (end < org_end && (type != EX_READ ||
				org_end - end >= F2FS_MIN_EXTENT_LEN)) {
			if (parts) {
				__set_extent_info(&ei,
					end, org_end - end,
					end - dei.fofs + dei.blk, false,
					type);
				en1 = __insert_extent_tree(sbi, et, &ei,
							NULL, NULL, true);
				next_en = en1;
			} else {
				__set_extent_info(&en->ei,
					end, en->ei.len - (end - dei.fofs),
					en->ei.blk + (end - dei.fofs), true,
					type);
				next_en = en;
			}
			parts++;
		}

		if (!next_en) {
			struct rb_node *node = rb_next(&en->rb_node);

			next_en = rb_entry_safe(node, struct extent_node,
						rb_node);
		}

		if (parts)
			__try_update_largest_extent(et, en);
		else
			__release_extent_node(sbi, et, en);

		/*
		 * if original extent is split into zero or two parts, extent
		 * tree has been altered by deletion or insertion, therefore
		 * invalidate pointers regard to tree.
		 */
		if (parts != 1) {
			insert_p = NULL;
			insert_parent = NULL;
		}
		en = next_en;
	}

	/* 3. update extent in read extent cache */
	BUG_ON(type != EX_READ);

	if (tei->blk) {
		__set_extent_info(&ei, fofs, len, tei->blk, false, EX_READ);
		if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en))
			__insert_extent_tree(sbi, et, &ei,
					insert_p, insert_parent, leftmost);

		/* give up extent_cache, if split and small updates happen */
		if (dei.len >= 1 &&
				prev.len < F2FS_MIN_EXTENT_LEN &&
				et->largest.len < F2FS_MIN_EXTENT_LEN) {
			et->largest.len = 0;
			et->largest_updated = true;
			set_inode_flag(inode, FI_NO_EXTENT);
		}
	}

	if (is_inode_flag_set(inode, FI_NO_EXTENT))
		__free_extent_tree(sbi, et);

	if (et->largest_updated) {
		et->largest_updated = false;
		updated = true;
	}

	write_unlock(&et->lock);

	if (updated)
		f2fs_mark_inode_dirty_sync(inode, true);
}

#ifdef CONFIG_F2FS_FS_COMPRESSION
void f2fs_update_read_extent_tree_range_compressed(struct inode *inode,
				pgoff_t fofs, block_t blkaddr, unsigned int llen,
				unsigned int c_len)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree *et = F2FS_I(inode)->extent_tree[EX_READ];
	struct extent_node *en = NULL;
	struct extent_node *prev_en = NULL, *next_en = NULL;
	struct extent_info ei;
	struct rb_node **insert_p = NULL, *insert_parent = NULL;
	bool leftmost = false;

	trace_f2fs_update_read_extent_tree_range(inode, fofs, llen,
						blkaddr, c_len);

	/* it is safe here to check FI_NO_EXTENT w/o et->lock in ro image */
	if (is_inode_flag_set(inode, FI_NO_EXTENT))
		return;

	write_lock(&et->lock);

	en = (struct extent_node *)f2fs_lookup_rb_tree_ret(&et->root,
				(struct rb_entry *)et->cached_en, fofs,
				(struct rb_entry **)&prev_en,
				(struct rb_entry **)&next_en,
				&insert_p, &insert_parent, false,
				&leftmost);
	if (en)
		goto unlock_out;

	__set_extent_info(&ei, fofs, llen, blkaddr, true, EX_READ);
	ei.c_len = c_len;

	if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en))
		__insert_extent_tree(sbi, et, &ei,
				insert_p, insert_parent, leftmost);
unlock_out:
	write_unlock(&et->lock);
}
#endif

static void __update_extent_cache(struct dnode_of_data *dn, enum extent_type type)
{
	struct extent_info ei;

	if (!__may_extent_tree(dn->inode, type))
		return;

	ei.fofs = f2fs_start_bidx_of_node(ofs_of_node(dn->node_page), dn->inode) +
								dn->ofs_in_node;
	ei.len = 1;

	if (type == EX_READ) {
		if (dn->data_blkaddr == NEW_ADDR)
			ei.blk = NULL_ADDR;
		else
			ei.blk = dn->data_blkaddr;
	}
	__update_extent_tree_range(dn->inode, &ei, type);
}

static unsigned int __shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink,
					enum extent_type type)
{
	struct extent_tree_info *eti = &sbi->extent_tree[type];
	struct extent_tree *et, *next;
	struct extent_node *en;
	unsigned int node_cnt = 0, tree_cnt = 0;
	int remained;

	if (!atomic_read(&eti->total_zombie_tree))
		goto free_node;

	if (!mutex_trylock(&eti->extent_tree_lock))
		goto out;

	/* 1. remove unreferenced extent tree */
	list_for_each_entry_safe(et, next, &eti->zombie_list, list) {
		if (atomic_read(&et->node_cnt)) {
			write_lock(&et->lock);
			node_cnt += __free_extent_tree(sbi, et);
			write_unlock(&et->lock);
		}
		f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
		list_del_init(&et->list);
		radix_tree_delete(&eti->extent_tree_root, et->ino);
		kmem_cache_free(extent_tree_slab, et);
		atomic_dec(&eti->total_ext_tree);
		atomic_dec(&eti->total_zombie_tree);
		tree_cnt++;

		if (node_cnt + tree_cnt >= nr_shrink)
			goto unlock_out;
		cond_resched();
	}
	mutex_unlock(&eti->extent_tree_lock);

free_node:
	/* 2. remove LRU extent entries */
	if (!mutex_trylock(&eti->extent_tree_lock))
		goto out;

	remained = nr_shrink - (node_cnt + tree_cnt);

	spin_lock(&eti->extent_lock);
	for (; remained > 0; remained--) {
		if (list_empty(&eti->extent_list))
			break;
		en = list_first_entry(&eti->extent_list,
					struct extent_node, list);
		et = en->et;
		if (!write_trylock(&et->lock)) {
			/* refresh this extent node's position in extent list */
			list_move_tail(&en->list, &eti->extent_list);
			continue;
		}

		list_del_init(&en->list);
		spin_unlock(&eti->extent_lock);

		__detach_extent_node(sbi, et, en);

		write_unlock(&et->lock);
		node_cnt++;
		spin_lock(&eti->extent_lock);
	}
	spin_unlock(&eti->extent_lock);

unlock_out:
	mutex_unlock(&eti->extent_tree_lock);
out:
	trace_f2fs_shrink_extent_tree(sbi, node_cnt, tree_cnt, type);

	return node_cnt + tree_cnt;
}

/* read extent cache operations */
bool f2fs_lookup_read_extent_cache(struct inode *inode, pgoff_t pgofs,
				struct extent_info *ei)
{
	if (!__may_extent_tree(inode, EX_READ))
		return false;

	return __lookup_extent_tree(inode, pgofs, ei, EX_READ);
}

void f2fs_update_read_extent_cache(struct dnode_of_data *dn)
{
	return __update_extent_cache(dn, EX_READ);
}

void f2fs_update_read_extent_cache_range(struct dnode_of_data *dn,
				pgoff_t fofs, block_t blkaddr, unsigned int len)
{
	struct extent_info ei = {
		.fofs = fofs,
		.len = len,
		.blk = blkaddr,
	};

	if (!__may_extent_tree(dn->inode, EX_READ))
		return;

	__update_extent_tree_range(dn->inode, &ei, EX_READ);
}

unsigned int f2fs_shrink_read_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
{
	if (!test_opt(sbi, READ_EXTENT_CACHE))
		return 0;

	return __shrink_extent_tree(sbi, nr_shrink, EX_READ);
}

static unsigned int __destroy_extent_node(struct inode *inode,
					enum extent_type type)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
	unsigned int node_cnt = 0;

	if (!et || !atomic_read(&et->node_cnt))
		return 0;

	write_lock(&et->lock);
	node_cnt = __free_extent_tree(sbi, et);
	write_unlock(&et->lock);

	return node_cnt;
}

void f2fs_destroy_extent_node(struct inode *inode)
{
	__destroy_extent_node(inode, EX_READ);
}

static void __drop_extent_tree(struct inode *inode, enum extent_type type)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
	bool updated = false;

	if (!__may_extent_tree(inode, type))
		return;

	write_lock(&et->lock);
	__free_extent_tree(sbi, et);
	if (type == EX_READ) {
		set_inode_flag(inode, FI_NO_EXTENT);
		if (et->largest.len) {
			et->largest.len = 0;
			updated = true;
		}
	}
	write_unlock(&et->lock);
	if (updated)
		f2fs_mark_inode_dirty_sync(inode, true);
}

void f2fs_drop_extent_tree(struct inode *inode)
{
	__drop_extent_tree(inode, EX_READ);
}

static void __destroy_extent_tree(struct inode *inode, enum extent_type type)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct extent_tree_info *eti = &sbi->extent_tree[type];
	struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
	unsigned int node_cnt = 0;

	if (!et)
		return;

	if (inode->i_nlink && !is_bad_inode(inode) &&
					atomic_read(&et->node_cnt)) {
		mutex_lock(&eti->extent_tree_lock);
		list_add_tail(&et->list, &eti->zombie_list);
		atomic_inc(&eti->total_zombie_tree);
		mutex_unlock(&eti->extent_tree_lock);
		return;
	}

	/* free all extent info belong to this extent tree */
	node_cnt = __destroy_extent_node(inode, type);

	/* delete extent tree entry in radix tree */
	mutex_lock(&eti->extent_tree_lock);
	f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
	radix_tree_delete(&eti->extent_tree_root, inode->i_ino);
	kmem_cache_free(extent_tree_slab, et);
	atomic_dec(&eti->total_ext_tree);
	mutex_unlock(&eti->extent_tree_lock);

	F2FS_I(inode)->extent_tree[type] = NULL;

	trace_f2fs_destroy_extent_tree(inode, node_cnt, type);
}

void f2fs_destroy_extent_tree(struct inode *inode)
{
	__destroy_extent_tree(inode, EX_READ);
}

static void __init_extent_tree_info(struct extent_tree_info *eti)
{
	INIT_RADIX_TREE(&eti->extent_tree_root, GFP_NOIO);
	mutex_init(&eti->extent_tree_lock);
	INIT_LIST_HEAD(&eti->extent_list);
	spin_lock_init(&eti->extent_lock);
	atomic_set(&eti->total_ext_tree, 0);
	INIT_LIST_HEAD(&eti->zombie_list);
	atomic_set(&eti->total_zombie_tree, 0);
	atomic_set(&eti->total_ext_node, 0);
}

void f2fs_init_extent_cache_info(struct f2fs_sb_info *sbi)
{
	__init_extent_tree_info(&sbi->extent_tree[EX_READ]);
}

int __init f2fs_create_extent_cache(void)
{
	extent_tree_slab = f2fs_kmem_cache_create("f2fs_extent_tree",
			sizeof(struct extent_tree));
	if (!extent_tree_slab)
		return -ENOMEM;
	extent_node_slab = f2fs_kmem_cache_create("f2fs_extent_node",
			sizeof(struct extent_node));
	if (!extent_node_slab) {
		kmem_cache_destroy(extent_tree_slab);
		return -ENOMEM;
	}
	return 0;
}

void f2fs_destroy_extent_cache(void)
{
	kmem_cache_destroy(extent_node_slab);
	kmem_cache_destroy(extent_tree_slab);
}