1 files changed, 748 insertions, 0 deletions

diff --git a/kernel/fs/f2fs/extent_cache.c b/kernel/fs/f2fs/extent_cache.c
new file mode 100644
index 000000000..7ddba812e
--- /dev/null
+++ b/kernel/fs/f2fs/extent_cache.c
@@ -0,0 +1,748 @@
+/*
+ * 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>
+ *
+ * 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 "f2fs.h"
+#include "node.h"
+#include <trace/events/f2fs.h>
+
+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)
+{
+	struct extent_node *en;
+
+	en = kmem_cache_alloc(extent_node_slab, GFP_ATOMIC);
+	if (!en)
+		return NULL;
+
+	en->ei = *ei;
+	INIT_LIST_HEAD(&en->list);
+
+	rb_link_node(&en->rb_node, parent, p);
+	rb_insert_color(&en->rb_node, &et->root);
+	et->count++;
+	atomic_inc(&sbi->total_ext_node);
+	return en;
+}
+
+static void __detach_extent_node(struct f2fs_sb_info *sbi,
+				struct extent_tree *et, struct extent_node *en)
+{
+	rb_erase(&en->rb_node, &et->root);
+	et->count--;
+	atomic_dec(&sbi->total_ext_node);
+
+	if (et->cached_en == en)
+		et->cached_en = NULL;
+}
+
+static struct extent_tree *__grab_extent_tree(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct extent_tree *et;
+	nid_t ino = inode->i_ino;
+
+	down_write(&sbi->extent_tree_lock);
+	et = radix_tree_lookup(&sbi->extent_tree_root, ino);
+	if (!et) {
+		et = f2fs_kmem_cache_alloc(extent_tree_slab, GFP_NOFS);
+		f2fs_radix_tree_insert(&sbi->extent_tree_root, ino, et);
+		memset(et, 0, sizeof(struct extent_tree));
+		et->ino = ino;
+		et->root = RB_ROOT;
+		et->cached_en = NULL;
+		rwlock_init(&et->lock);
+		atomic_set(&et->refcount, 0);
+		et->count = 0;
+		sbi->total_ext_tree++;
+	}
+	atomic_inc(&et->refcount);
+	up_write(&sbi->extent_tree_lock);
+
+	/* never died until evict_inode */
+	F2FS_I(inode)->extent_tree = et;
+
+	return et;
+}
+
+static struct extent_node *__lookup_extent_tree(struct f2fs_sb_info *sbi,
+				struct extent_tree *et, unsigned int fofs)
+{
+	struct rb_node *node = et->root.rb_node;
+	struct extent_node *en = et->cached_en;
+
+	if (en) {
+		struct extent_info *cei = &en->ei;
+
+		if (cei->fofs <= fofs && cei->fofs + cei->len > fofs) {
+			stat_inc_cached_node_hit(sbi);
+			return en;
+		}
+	}
+
+	while (node) {
+		en = rb_entry(node, struct extent_node, rb_node);
+
+		if (fofs < en->ei.fofs) {
+			node = node->rb_left;
+		} else if (fofs >= en->ei.fofs + en->ei.len) {
+			node = node->rb_right;
+		} else {
+			stat_inc_rbtree_node_hit(sbi);
+			return en;
+		}
+	}
+	return NULL;
+}
+
+static struct extent_node *__init_extent_tree(struct f2fs_sb_info *sbi,
+				struct extent_tree *et, struct extent_info *ei)
+{
+	struct rb_node **p = &et->root.rb_node;
+	struct extent_node *en;
+
+	en = __attach_extent_node(sbi, et, ei, NULL, p);
+	if (!en)
+		return NULL;
+
+	et->largest = en->ei;
+	et->cached_en = en;
+	return en;
+}
+
+static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
+					struct extent_tree *et, bool free_all)
+{
+	struct rb_node *node, *next;
+	struct extent_node *en;
+	unsigned int count = et->count;
+
+	node = rb_first(&et->root);
+	while (node) {
+		next = rb_next(node);
+		en = rb_entry(node, struct extent_node, rb_node);
+
+		if (free_all) {
+			spin_lock(&sbi->extent_lock);
+			if (!list_empty(&en->list))
+				list_del_init(&en->list);
+			spin_unlock(&sbi->extent_lock);
+		}
+
+		if (free_all || list_empty(&en->list)) {
+			__detach_extent_node(sbi, et, en);
+			kmem_cache_free(extent_node_slab, en);
+		}
+		node = next;
+	}
+
+	return count - et->count;
+}
+
+static void __drop_largest_extent(struct inode *inode,
+					pgoff_t fofs, unsigned int len)
+{
+	struct extent_info *largest = &F2FS_I(inode)->extent_tree->largest;
+
+	if (fofs < largest->fofs + largest->len && fofs + len > largest->fofs)
+		largest->len = 0;
+}
+
+void f2fs_drop_largest_extent(struct inode *inode, pgoff_t fofs)
+{
+	if (!f2fs_may_extent_tree(inode))
+		return;
+
+	__drop_largest_extent(inode, fofs, 1);
+}
+
+void f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct extent_tree *et;
+	struct extent_node *en;
+	struct extent_info ei;
+
+	if (!f2fs_may_extent_tree(inode))
+		return;
+
+	et = __grab_extent_tree(inode);
+
+	if (!i_ext || le32_to_cpu(i_ext->len) < F2FS_MIN_EXTENT_LEN)
+		return;
+
+	set_extent_info(&ei, le32_to_cpu(i_ext->fofs),
+		le32_to_cpu(i_ext->blk), le32_to_cpu(i_ext->len));
+
+	write_lock(&et->lock);
+	if (et->count)
+		goto out;
+
+	en = __init_extent_tree(sbi, et, &ei);
+	if (en) {
+		spin_lock(&sbi->extent_lock);
+		list_add_tail(&en->list, &sbi->extent_list);
+		spin_unlock(&sbi->extent_lock);
+	}
+out:
+	write_unlock(&et->lock);
+}
+
+static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
+							struct extent_info *ei)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct extent_tree *et = F2FS_I(inode)->extent_tree;
+	struct extent_node *en;
+	bool ret = false;
+
+	f2fs_bug_on(sbi, !et);
+
+	trace_f2fs_lookup_extent_tree_start(inode, pgofs);
+
+	read_lock(&et->lock);
+
+	if (et->largest.fofs <= pgofs &&
+			et->largest.fofs + et->largest.len > pgofs) {
+		*ei = et->largest;
+		ret = true;
+		stat_inc_largest_node_hit(sbi);
+		goto out;
+	}
+
+	en = __lookup_extent_tree(sbi, et, pgofs);
+	if (en) {
+		*ei = en->ei;
+		spin_lock(&sbi->extent_lock);
+		if (!list_empty(&en->list))
+			list_move_tail(&en->list, &sbi->extent_list);
+		et->cached_en = en;
+		spin_unlock(&sbi->extent_lock);
+		ret = true;
+	}
+out:
+	stat_inc_total_hit(sbi);
+	read_unlock(&et->lock);
+
+	trace_f2fs_lookup_extent_tree_end(inode, pgofs, ei);
+	return ret;
+}
+
+
+/*
+ * lookup extent at @fofs, if hit, return the extent
+ * if not, return NULL and
+ * @prev_ex: extent before fofs
+ * @next_ex: extent after fofs
+ * @insert_p: insert point for new extent at fofs
+ * in order to simpfy the insertion after.
+ * tree must stay unchanged between lookup and insertion.
+ */
+static struct extent_node *__lookup_extent_tree_ret(struct extent_tree *et,
+				unsigned int fofs,
+				struct extent_node **prev_ex,
+				struct extent_node **next_ex,
+				struct rb_node ***insert_p,
+				struct rb_node **insert_parent)
+{
+	struct rb_node **pnode = &et->root.rb_node;
+	struct rb_node *parent = NULL, *tmp_node;
+	struct extent_node *en = et->cached_en;
+
+	*insert_p = NULL;
+	*insert_parent = NULL;
+	*prev_ex = NULL;
+	*next_ex = NULL;
+
+	if (RB_EMPTY_ROOT(&et->root))
+		return NULL;
+
+	if (en) {
+		struct extent_info *cei = &en->ei;
+
+		if (cei->fofs <= fofs && cei->fofs + cei->len > fofs)
+			goto lookup_neighbors;
+	}
+
+	while (*pnode) {
+		parent = *pnode;
+		en = rb_entry(*pnode, struct extent_node, rb_node);
+
+		if (fofs < en->ei.fofs)
+			pnode = &(*pnode)->rb_left;
+		else if (fofs >= en->ei.fofs + en->ei.len)
+			pnode = &(*pnode)->rb_right;
+		else
+			goto lookup_neighbors;
+	}
+
+	*insert_p = pnode;
+	*insert_parent = parent;
+
+	en = rb_entry(parent, struct extent_node, rb_node);
+	tmp_node = parent;
+	if (parent && fofs > en->ei.fofs)
+		tmp_node = rb_next(parent);
+	*next_ex = tmp_node ?
+		rb_entry(tmp_node, struct extent_node, rb_node) : NULL;
+
+	tmp_node = parent;
+	if (parent && fofs < en->ei.fofs)
+		tmp_node = rb_prev(parent);
+	*prev_ex = tmp_node ?
+		rb_entry(tmp_node, struct extent_node, rb_node) : NULL;
+	return NULL;
+
+lookup_neighbors:
+	if (fofs == en->ei.fofs) {
+		/* lookup prev node for merging backward later */
+		tmp_node = rb_prev(&en->rb_node);
+		*prev_ex = tmp_node ?
+			rb_entry(tmp_node, struct extent_node, rb_node) : NULL;
+	}
+	if (fofs == en->ei.fofs + en->ei.len - 1) {
+		/* lookup next node for merging frontward later */
+		tmp_node = rb_next(&en->rb_node);
+		*next_ex = tmp_node ?
+			rb_entry(tmp_node, struct extent_node, rb_node) : NULL;
+	}
+	return en;
+}
+
+static struct extent_node *__try_merge_extent_node(struct f2fs_sb_info *sbi,
+				struct extent_tree *et, struct extent_info *ei,
+				struct extent_node **den,
+				struct extent_node *prev_ex,
+				struct extent_node *next_ex)
+{
+	struct extent_node *en = NULL;
+
+	if (prev_ex && __is_back_mergeable(ei, &prev_ex->ei)) {
+		prev_ex->ei.len += ei->len;
+		ei = &prev_ex->ei;
+		en = prev_ex;
+	}
+
+	if (next_ex && __is_front_mergeable(ei, &next_ex->ei)) {
+		if (en) {
+			__detach_extent_node(sbi, et, prev_ex);
+			*den = prev_ex;
+		}
+		next_ex->ei.fofs = ei->fofs;
+		next_ex->ei.blk = ei->blk;
+		next_ex->ei.len += ei->len;
+		en = next_ex;
+	}
+
+	if (en) {
+		__try_update_largest_extent(et, en);
+		et->cached_en = en;
+	}
+	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)
+{
+	struct rb_node **p = &et->root.rb_node;
+	struct rb_node *parent = NULL;
+	struct extent_node *en = NULL;
+
+	if (insert_p && insert_parent) {
+		parent = insert_parent;
+		p = insert_p;
+		goto do_insert;
+	}
+
+	while (*p) {
+		parent = *p;
+		en = rb_entry(parent, struct extent_node, rb_node);
+
+		if (ei->fofs < en->ei.fofs)
+			p = &(*p)->rb_left;
+		else if (ei->fofs >= en->ei.fofs + en->ei.len)
+			p = &(*p)->rb_right;
+		else
+			f2fs_bug_on(sbi, 1);
+	}
+do_insert:
+	en = __attach_extent_node(sbi, et, ei, parent, p);
+	if (!en)
+		return NULL;
+
+	__try_update_largest_extent(et, en);
+	et->cached_en = en;
+	return en;
+}
+
+static unsigned int f2fs_update_extent_tree_range(struct inode *inode,
+				pgoff_t fofs, block_t blkaddr, unsigned int len)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct extent_tree *et = F2FS_I(inode)->extent_tree;
+	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 end = fofs + len;
+	unsigned int pos = (unsigned int)fofs;
+
+	if (!et)
+		return false;
+
+	trace_f2fs_update_extent_tree_range(inode, fofs, blkaddr, len);
+
+	write_lock(&et->lock);
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT)) {
+		write_unlock(&et->lock);
+		return false;
+	}
+
+	prev = et->largest;
+	dei.len = 0;
+
+	/*
+	 * drop largest extent before lookup, in case it's already
+	 * been shrunk from extent tree
+	 */
+	__drop_largest_extent(inode, fofs, len);
+
+	/* 1. lookup first extent node in range [fofs, fofs + len - 1] */
+	en = __lookup_extent_tree_ret(et, fofs, &prev_en, &next_en,
+					&insert_p, &insert_parent);
+	if (!en)
+		en = next_en;
+
+	/* 2. invlidate 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, pos >= org_end);
+
+		if (pos > dei.fofs &&	pos - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
+			en->ei.len = pos - en->ei.fofs;
+			prev_en = en;
+			parts = 1;
+		}
+
+		if (end < org_end && org_end - end >= F2FS_MIN_EXTENT_LEN) {
+			if (parts) {
+				set_extent_info(&ei, end,
+						end - dei.fofs + dei.blk,
+						org_end - end);
+				en1 = __insert_extent_tree(sbi, et, &ei,
+							NULL, NULL);
+				next_en = en1;
+			} else {
+				en->ei.fofs = end;
+				en->ei.blk += end - dei.fofs;
+				en->ei.len -= end - dei.fofs;
+				next_en = en;
+			}
+			parts++;
+		}
+
+		if (!next_en) {
+			struct rb_node *node = rb_next(&en->rb_node);
+
+			next_en = node ?
+				rb_entry(node, struct extent_node, rb_node)
+				: NULL;
+		}
+
+		if (parts)
+			__try_update_largest_extent(et, en);
+		else
+			__detach_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;
+		}
+
+		/* update in global extent list */
+		spin_lock(&sbi->extent_lock);
+		if (!parts && !list_empty(&en->list))
+			list_del(&en->list);
+		if (en1)
+			list_add_tail(&en1->list, &sbi->extent_list);
+		spin_unlock(&sbi->extent_lock);
+
+		/* release extent node */
+		if (!parts)
+			kmem_cache_free(extent_node_slab, en);
+
+		en = next_en;
+	}
+
+	/* 3. update extent in extent cache */
+	if (blkaddr) {
+		struct extent_node *den = NULL;
+
+		set_extent_info(&ei, fofs, blkaddr, len);
+		en1 = __try_merge_extent_node(sbi, et, &ei, &den,
+							prev_en, next_en);
+		if (!en1)
+			en1 = __insert_extent_tree(sbi, et, &ei,
+						insert_p, insert_parent);
+
+		/* 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;
+			set_inode_flag(F2FS_I(inode), FI_NO_EXTENT);
+		}
+
+		spin_lock(&sbi->extent_lock);
+		if (en1) {
+			if (list_empty(&en1->list))
+				list_add_tail(&en1->list, &sbi->extent_list);
+			else
+				list_move_tail(&en1->list, &sbi->extent_list);
+		}
+		if (den && !list_empty(&den->list))
+			list_del(&den->list);
+		spin_unlock(&sbi->extent_lock);
+
+		if (den)
+			kmem_cache_free(extent_node_slab, den);
+	}
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
+		__free_extent_tree(sbi, et, true);
+
+	write_unlock(&et->lock);
+
+	return !__is_extent_same(&prev, &et->largest);
+}
+
+unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
+{
+	struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
+	struct extent_node *en, *tmp;
+	unsigned long ino = F2FS_ROOT_INO(sbi);
+	struct radix_tree_root *root = &sbi->extent_tree_root;
+	unsigned int found;
+	unsigned int node_cnt = 0, tree_cnt = 0;
+	int remained;
+
+	if (!test_opt(sbi, EXTENT_CACHE))
+		return 0;
+
+	if (!down_write_trylock(&sbi->extent_tree_lock))
+		goto out;
+
+	/* 1. remove unreferenced extent tree */
+	while ((found = radix_tree_gang_lookup(root,
+				(void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
+		unsigned i;
+
+		ino = treevec[found - 1]->ino + 1;
+		for (i = 0; i < found; i++) {
+			struct extent_tree *et = treevec[i];
+
+			if (!atomic_read(&et->refcount)) {
+				write_lock(&et->lock);
+				node_cnt += __free_extent_tree(sbi, et, true);
+				write_unlock(&et->lock);
+
+				radix_tree_delete(root, et->ino);
+				kmem_cache_free(extent_tree_slab, et);
+				sbi->total_ext_tree--;
+				tree_cnt++;
+
+				if (node_cnt + tree_cnt >= nr_shrink)
+					goto unlock_out;
+			}
+		}
+	}
+	up_write(&sbi->extent_tree_lock);
+
+	/* 2. remove LRU extent entries */
+	if (!down_write_trylock(&sbi->extent_tree_lock))
+		goto out;
+
+	remained = nr_shrink - (node_cnt + tree_cnt);
+
+	spin_lock(&sbi->extent_lock);
+	list_for_each_entry_safe(en, tmp, &sbi->extent_list, list) {
+		if (!remained--)
+			break;
+		list_del_init(&en->list);
+	}
+	spin_unlock(&sbi->extent_lock);
+
+	/*
+	 * reset ino for searching victims from beginning of global extent tree.
+	 */
+	ino = F2FS_ROOT_INO(sbi);
+
+	while ((found = radix_tree_gang_lookup(root,
+				(void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
+		unsigned i;
+
+		ino = treevec[found - 1]->ino + 1;
+		for (i = 0; i < found; i++) {
+			struct extent_tree *et = treevec[i];
+
+			write_lock(&et->lock);
+			node_cnt += __free_extent_tree(sbi, et, false);
+			write_unlock(&et->lock);
+
+			if (node_cnt + tree_cnt >= nr_shrink)
+				goto unlock_out;
+		}
+	}
+unlock_out:
+	up_write(&sbi->extent_tree_lock);
+out:
+	trace_f2fs_shrink_extent_tree(sbi, node_cnt, tree_cnt);
+
+	return node_cnt + tree_cnt;
+}
+
+unsigned int f2fs_destroy_extent_node(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct extent_tree *et = F2FS_I(inode)->extent_tree;
+	unsigned int node_cnt = 0;
+
+	if (!et)
+		return 0;
+
+	write_lock(&et->lock);
+	node_cnt = __free_extent_tree(sbi, et, true);
+	write_unlock(&et->lock);
+
+	return node_cnt;
+}
+
+void f2fs_destroy_extent_tree(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct extent_tree *et = F2FS_I(inode)->extent_tree;
+	unsigned int node_cnt = 0;
+
+	if (!et)
+		return;
+
+	if (inode->i_nlink && !is_bad_inode(inode) && et->count) {
+		atomic_dec(&et->refcount);
+		return;
+	}
+
+	/* free all extent info belong to this extent tree */
+	node_cnt = f2fs_destroy_extent_node(inode);
+
+	/* delete extent tree entry in radix tree */
+	down_write(&sbi->extent_tree_lock);
+	atomic_dec(&et->refcount);
+	f2fs_bug_on(sbi, atomic_read(&et->refcount) || et->count);
+	radix_tree_delete(&sbi->extent_tree_root, inode->i_ino);
+	kmem_cache_free(extent_tree_slab, et);
+	sbi->total_ext_tree--;
+	up_write(&sbi->extent_tree_lock);
+
+	F2FS_I(inode)->extent_tree = NULL;
+
+	trace_f2fs_destroy_extent_tree(inode, node_cnt);
+}
+
+bool f2fs_lookup_extent_cache(struct inode *inode, pgoff_t pgofs,
+					struct extent_info *ei)
+{
+	if (!f2fs_may_extent_tree(inode))
+		return false;
+
+	return f2fs_lookup_extent_tree(inode, pgofs, ei);
+}
+
+void f2fs_update_extent_cache(struct dnode_of_data *dn)
+{
+	struct f2fs_inode_info *fi = F2FS_I(dn->inode);
+	pgoff_t fofs;
+
+	if (!f2fs_may_extent_tree(dn->inode))
+		return;
+
+	f2fs_bug_on(F2FS_I_SB(dn->inode), dn->data_blkaddr == NEW_ADDR);
+
+
+	fofs = start_bidx_of_node(ofs_of_node(dn->node_page), fi) +
+							dn->ofs_in_node;
+
+	if (f2fs_update_extent_tree_range(dn->inode, fofs, dn->data_blkaddr, 1))
+		sync_inode_page(dn);
+}
+
+void f2fs_update_extent_cache_range(struct dnode_of_data *dn,
+				pgoff_t fofs, block_t blkaddr, unsigned int len)
+
+{
+	if (!f2fs_may_extent_tree(dn->inode))
+		return;
+
+	if (f2fs_update_extent_tree_range(dn->inode, fofs, blkaddr, len))
+		sync_inode_page(dn);
+}
+
+void init_extent_cache_info(struct f2fs_sb_info *sbi)
+{
+	INIT_RADIX_TREE(&sbi->extent_tree_root, GFP_NOIO);
+	init_rwsem(&sbi->extent_tree_lock);
+	INIT_LIST_HEAD(&sbi->extent_list);
+	spin_lock_init(&sbi->extent_lock);
+	sbi->total_ext_tree = 0;
+	atomic_set(&sbi->total_ext_node, 0);
+}
+
+int __init 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 destroy_extent_cache(void)
+{
+	kmem_cache_destroy(extent_node_slab);
+	kmem_cache_destroy(extent_tree_slab);
+}