f2fs: maintain extent cache in separated file

This patch moves extent cache related code from data.c into extent_cache.c
since extent cache is independent feature, and its codes are not relate to
others in data.c, it's better for us to maintain them in separated place.

There is no functionality change, but several small coding style fixes
including:
* rename __drop_largest_extent to f2fs_drop_largest_extent for exporting;
* rename misspelled word 'untill' to 'until';
* remove unneeded 'return' in the end of f2fs_destroy_extent_tree().

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/Makefile

@@ -2,7 +2,7 @@ obj-$(CONFIG_F2FS_FS) += f2fs.o
 
 f2fs-y		:= dir.o file.o inode.o namei.o hash.o super.o inline.o
 f2fs-y		+= checkpoint.o gc.o data.o node.o segment.o recovery.o
-f2fs-y		+= shrinker.o
+f2fs-y		+= shrinker.o extent_cache.o
 f2fs-$(CONFIG_F2FS_STAT_FS) += debug.o
 f2fs-$(CONFIG_F2FS_FS_XATTR) += xattr.o
 f2fs-$(CONFIG_F2FS_FS_POSIX_ACL) += acl.o

fs/f2fs/data.c

@@ -26,9 +26,6 @@
 #include "trace.h"
 #include <trace/events/f2fs.h>
 
-static struct kmem_cache *extent_tree_slab;
-static struct kmem_cache *extent_node_slab;
-
 static void f2fs_read_end_io(struct bio *bio, int err)
 {
 	struct bio_vec *bvec;
@@ -266,548 +263,6 @@ int f2fs_reserve_block(struct dnode_of_data *dn, pgoff_t index)
 	return err;
 }
 
-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 untill evict_inode */
-	F2FS_I(inode)->extent_tree = et;
-
-	return et;
-}
-
-static struct extent_node *__lookup_extent_tree(struct extent_tree *et,
-							unsigned int fofs)
-{
-	struct rb_node *node = et->root.rb_node;
-	struct extent_node *en;
-
-	if (et->cached_en) {
-		struct extent_info *cei = &et->cached_en->ei;
-
-		if (cei->fofs <= fofs && cei->fofs + cei->len > fofs)
-			return et->cached_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
-			return en;
-	}
-	return NULL;
-}
-
-static struct extent_node *__try_back_merge(struct f2fs_sb_info *sbi,
-				struct extent_tree *et, struct extent_node *en)
-{
-	struct extent_node *prev;
-	struct rb_node *node;
-
-	node = rb_prev(&en->rb_node);
-	if (!node)
-		return NULL;
-
-	prev = rb_entry(node, struct extent_node, rb_node);
-	if (__is_back_mergeable(&en->ei, &prev->ei)) {
-		en->ei.fofs = prev->ei.fofs;
-		en->ei.blk = prev->ei.blk;
-		en->ei.len += prev->ei.len;
-		__detach_extent_node(sbi, et, prev);
-		return prev;
-	}
-	return NULL;
-}
-
-static struct extent_node *__try_front_merge(struct f2fs_sb_info *sbi,
-				struct extent_tree *et, struct extent_node *en)
-{
-	struct extent_node *next;
-	struct rb_node *node;
-
-	node = rb_next(&en->rb_node);
-	if (!node)
-		return NULL;
-
-	next = rb_entry(node, struct extent_node, rb_node);
-	if (__is_front_mergeable(&en->ei, &next->ei)) {
-		en->ei.len += next->ei.len;
-		__detach_extent_node(sbi, et, next);
-		return next;
-	}
-	return NULL;
-}
-
-static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
-				struct extent_tree *et, struct extent_info *ei,
-				struct extent_node **den)
-{
-	struct rb_node **p = &et->root.rb_node;
-	struct rb_node *parent = NULL;
-	struct extent_node *en;
-
-	while (*p) {
-		parent = *p;
-		en = rb_entry(parent, struct extent_node, rb_node);
-
-		if (ei->fofs < en->ei.fofs) {
-			if (__is_front_mergeable(ei, &en->ei)) {
-				f2fs_bug_on(sbi, !den);
-				en->ei.fofs = ei->fofs;
-				en->ei.blk = ei->blk;
-				en->ei.len += ei->len;
-				*den = __try_back_merge(sbi, et, en);
-				goto update_out;
-			}
-			p = &(*p)->rb_left;
-		} else if (ei->fofs >= en->ei.fofs + en->ei.len) {
-			if (__is_back_mergeable(ei, &en->ei)) {
-				f2fs_bug_on(sbi, !den);
-				en->ei.len += ei->len;
-				*den = __try_front_merge(sbi, et, en);
-				goto update_out;
-			}
-			p = &(*p)->rb_right;
-		} else {
-			f2fs_bug_on(sbi, 1);
-		}
-	}
-
-	en = __attach_extent_node(sbi, et, ei, parent, p);
-	if (!en)
-		return NULL;
-update_out:
-	if (en->ei.len > et->largest.len)
-		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)
-{
-	struct extent_info *largest = &F2FS_I(inode)->extent_tree->largest;
-
-	if (largest->fofs <= fofs && largest->fofs + largest->len > fofs)
-		largest->len = 0;
-}
-
-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 = __insert_extent_tree(sbi, et, &ei, NULL);
-	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_read_hit(sbi->sb);
-		goto out;
-	}
-
-	en = __lookup_extent_tree(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;
-		stat_inc_read_hit(sbi->sb);
-	}
-out:
-	stat_inc_total_hit(sbi->sb);
-	read_unlock(&et->lock);
-
-	trace_f2fs_lookup_extent_tree_end(inode, pgofs, ei);
-	return ret;
-}
-
-/* return true, if on-disk extent should be updated */
-static bool f2fs_update_extent_tree(struct inode *inode, pgoff_t fofs,
-							block_t blkaddr)
-{
-	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, *en2 = NULL, *en3 = NULL;
-	struct extent_node *den = NULL;
-	struct extent_info ei, dei, prev;
-	unsigned int endofs;
-
-	if (!et)
-		return false;
-
-	trace_f2fs_update_extent_tree(inode, fofs, blkaddr);
-
-	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;
-
-	/* we do not guarantee that the largest extent is cached all the time */
-	__drop_largest_extent(inode, fofs);
-
-	/* 1. lookup and remove existing extent info in cache */
-	en = __lookup_extent_tree(et, fofs);
-	if (!en)
-		goto update_extent;
-
-	dei = en->ei;
-	__detach_extent_node(sbi, et, en);
-
-	/* 2. if extent can be split more, split and insert the left part */
-	if (dei.len > F2FS_MIN_EXTENT_LEN) {
-		/*  insert left part of split extent into cache */
-		if (fofs - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
-			set_extent_info(&ei, dei.fofs, dei.blk,
-							fofs - dei.fofs);
-			en1 = __insert_extent_tree(sbi, et, &ei, NULL);
-		}
-
-		/* insert right part of split extent into cache */
-		endofs = dei.fofs + dei.len - 1;
-		if (endofs - fofs >= F2FS_MIN_EXTENT_LEN) {
-			set_extent_info(&ei, fofs + 1,
-				fofs - dei.fofs + dei.blk + 1, endofs - fofs);
-			en2 = __insert_extent_tree(sbi, et, &ei, NULL);
-		}
-	}
-
-update_extent:
-	/* 3. update extent in extent cache */
-	if (blkaddr) {
-		set_extent_info(&ei, fofs, blkaddr, 1);
-		en3 = __insert_extent_tree(sbi, et, &ei, &den);
-
-		/* 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);
-		}
-	}
-
-	/* 4. update in global extent list */
-	spin_lock(&sbi->extent_lock);
-	if (en && !list_empty(&en->list))
-		list_del(&en->list);
-	/*
-	 * en1 and en2 split from en, they will become more and more smaller
-	 * fragments after splitting several times. So if the length is smaller
-	 * than F2FS_MIN_EXTENT_LEN, we will not add them into extent tree.
-	 */
-	if (en1)
-		list_add_tail(&en1->list, &sbi->extent_list);
-	if (en2)
-		list_add_tail(&en2->list, &sbi->extent_list);
-	if (en3) {
-		if (list_empty(&en3->list))
-			list_add_tail(&en3->list, &sbi->extent_list);
-		else
-			list_move_tail(&en3->list, &sbi->extent_list);
-	}
-	if (den && !list_empty(&den->list))
-		list_del(&den->list);
-	spin_unlock(&sbi->extent_lock);
-
-	/* 5. release extent node */
-	if (en)
-		kmem_cache_free(extent_node_slab, en);
-	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);
-
-	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)
-				break;
-		}
-	}
-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);
-	return;
-}
-
-static 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(dn->inode, fofs, dn->data_blkaddr))
-		sync_inode_page(dn);
-}
-
 struct page *get_read_data_page(struct inode *inode, pgoff_t index, int rw)
 {
 	struct address_space *mapping = inode->i_mapping;
@@ -1017,7 +472,7 @@ alloc:
 		i_size_write(dn->inode, ((fofs + 1) << PAGE_CACHE_SHIFT));
 
 	/* direct IO doesn't use extent cache to maximize the performance */
-	__drop_largest_extent(dn->inode, fofs);
+	f2fs_drop_largest_extent(dn->inode, fofs);
 
 	return 0;
 }
@@ -1997,37 +1452,6 @@ static sector_t f2fs_bmap(struct address_space *mapping, sector_t block)
 	return generic_block_bmap(mapping, block, get_data_block);
 }
 
-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);
-}
-
 const struct address_space_operations f2fs_dblock_aops = {
 	.readpage	= f2fs_read_data_page,
 	.readpages	= f2fs_read_data_pages,

fs/f2fs/extent_cache.c

@@ -0,0 +1,594 @@
+/*
+ * 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 extent_tree *et,
+							unsigned int fofs)
+{
+	struct rb_node *node = et->root.rb_node;
+	struct extent_node *en;
+
+	if (et->cached_en) {
+		struct extent_info *cei = &et->cached_en->ei;
+
+		if (cei->fofs <= fofs && cei->fofs + cei->len > fofs)
+			return et->cached_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
+			return en;
+	}
+	return NULL;
+}
+
+static struct extent_node *__try_back_merge(struct f2fs_sb_info *sbi,
+				struct extent_tree *et, struct extent_node *en)
+{
+	struct extent_node *prev;
+	struct rb_node *node;
+
+	node = rb_prev(&en->rb_node);
+	if (!node)
+		return NULL;
+
+	prev = rb_entry(node, struct extent_node, rb_node);
+	if (__is_back_mergeable(&en->ei, &prev->ei)) {
+		en->ei.fofs = prev->ei.fofs;
+		en->ei.blk = prev->ei.blk;
+		en->ei.len += prev->ei.len;
+		__detach_extent_node(sbi, et, prev);
+		return prev;
+	}
+	return NULL;
+}
+
+static struct extent_node *__try_front_merge(struct f2fs_sb_info *sbi,
+				struct extent_tree *et, struct extent_node *en)
+{
+	struct extent_node *next;
+	struct rb_node *node;
+
+	node = rb_next(&en->rb_node);
+	if (!node)
+		return NULL;
+
+	next = rb_entry(node, struct extent_node, rb_node);
+	if (__is_front_mergeable(&en->ei, &next->ei)) {
+		en->ei.len += next->ei.len;
+		__detach_extent_node(sbi, et, next);
+		return next;
+	}
+	return NULL;
+}
+
+static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
+				struct extent_tree *et, struct extent_info *ei,
+				struct extent_node **den)
+{
+	struct rb_node **p = &et->root.rb_node;
+	struct rb_node *parent = NULL;
+	struct extent_node *en;
+
+	while (*p) {
+		parent = *p;
+		en = rb_entry(parent, struct extent_node, rb_node);
+
+		if (ei->fofs < en->ei.fofs) {
+			if (__is_front_mergeable(ei, &en->ei)) {
+				f2fs_bug_on(sbi, !den);
+				en->ei.fofs = ei->fofs;
+				en->ei.blk = ei->blk;
+				en->ei.len += ei->len;
+				*den = __try_back_merge(sbi, et, en);
+				goto update_out;
+			}
+			p = &(*p)->rb_left;
+		} else if (ei->fofs >= en->ei.fofs + en->ei.len) {
+			if (__is_back_mergeable(ei, &en->ei)) {
+				f2fs_bug_on(sbi, !den);
+				en->ei.len += ei->len;
+				*den = __try_front_merge(sbi, et, en);
+				goto update_out;
+			}
+			p = &(*p)->rb_right;
+		} else {
+			f2fs_bug_on(sbi, 1);
+		}
+	}
+
+	en = __attach_extent_node(sbi, et, ei, parent, p);
+	if (!en)
+		return NULL;
+update_out:
+	if (en->ei.len > et->largest.len)
+		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;
+}
+
+void f2fs_drop_largest_extent(struct inode *inode, pgoff_t fofs)
+{
+	struct extent_info *largest = &F2FS_I(inode)->extent_tree->largest;
+
+	if (largest->fofs <= fofs && largest->fofs + largest->len > fofs)
+		largest->len = 0;
+}
+
+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 = __insert_extent_tree(sbi, et, &ei, NULL);
+	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_read_hit(sbi->sb);
+		goto out;
+	}
+
+	en = __lookup_extent_tree(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;
+		stat_inc_read_hit(sbi->sb);
+	}
+out:
+	stat_inc_total_hit(sbi->sb);
+	read_unlock(&et->lock);
+
+	trace_f2fs_lookup_extent_tree_end(inode, pgofs, ei);
+	return ret;
+}
+
+/* return true, if on-disk extent should be updated */
+static bool f2fs_update_extent_tree(struct inode *inode, pgoff_t fofs,
+							block_t blkaddr)
+{
+	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, *en2 = NULL, *en3 = NULL;
+	struct extent_node *den = NULL;
+	struct extent_info ei, dei, prev;
+	unsigned int endofs;
+
+	if (!et)
+		return false;
+
+	trace_f2fs_update_extent_tree(inode, fofs, blkaddr);
+
+	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;
+
+	/* we do not guarantee that the largest extent is cached all the time */
+	f2fs_drop_largest_extent(inode, fofs);
+
+	/* 1. lookup and remove existing extent info in cache */
+	en = __lookup_extent_tree(et, fofs);
+	if (!en)
+		goto update_extent;
+
+	dei = en->ei;
+	__detach_extent_node(sbi, et, en);
+
+	/* 2. if extent can be split more, split and insert the left part */
+	if (dei.len > F2FS_MIN_EXTENT_LEN) {
+		/*  insert left part of split extent into cache */
+		if (fofs - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
+			set_extent_info(&ei, dei.fofs, dei.blk,
+							fofs - dei.fofs);
+			en1 = __insert_extent_tree(sbi, et, &ei, NULL);
+		}
+
+		/* insert right part of split extent into cache */
+		endofs = dei.fofs + dei.len - 1;
+		if (endofs - fofs >= F2FS_MIN_EXTENT_LEN) {
+			set_extent_info(&ei, fofs + 1,
+				fofs - dei.fofs + dei.blk + 1, endofs - fofs);
+			en2 = __insert_extent_tree(sbi, et, &ei, NULL);
+		}
+	}
+
+update_extent:
+	/* 3. update extent in extent cache */
+	if (blkaddr) {
+		set_extent_info(&ei, fofs, blkaddr, 1);
+		en3 = __insert_extent_tree(sbi, et, &ei, &den);
+
+		/* 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);
+		}
+	}
+
+	/* 4. update in global extent list */
+	spin_lock(&sbi->extent_lock);
+	if (en && !list_empty(&en->list))
+		list_del(&en->list);
+	/*
+	 * en1 and en2 split from en, they will become more and more smaller
+	 * fragments after splitting several times. So if the length is smaller
+	 * than F2FS_MIN_EXTENT_LEN, we will not add them into extent tree.
+	 */
+	if (en1)
+		list_add_tail(&en1->list, &sbi->extent_list);
+	if (en2)
+		list_add_tail(&en2->list, &sbi->extent_list);
+	if (en3) {
+		if (list_empty(&en3->list))
+			list_add_tail(&en3->list, &sbi->extent_list);
+		else
+			list_move_tail(&en3->list, &sbi->extent_list);
+	}
+	if (den && !list_empty(&den->list))
+		list_del(&den->list);
+	spin_unlock(&sbi->extent_lock);
+
+	/* 5. release extent node */
+	if (en)
+		kmem_cache_free(extent_node_slab, en);
+	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);
+
+	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)
+				break;
+		}
+	}
+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(dn->inode, fofs, dn->data_blkaddr))
+		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);
+}

fs/f2fs/f2fs.h

@@ -1766,20 +1766,12 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *);
 void set_data_blkaddr(struct dnode_of_data *);
 int reserve_new_block(struct dnode_of_data *);
 int f2fs_reserve_block(struct dnode_of_data *, pgoff_t);
-unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
-void f2fs_init_extent_tree(struct inode *, struct f2fs_extent *);
-unsigned int f2fs_destroy_extent_node(struct inode *);
-void f2fs_destroy_extent_tree(struct inode *);
-void f2fs_update_extent_cache(struct dnode_of_data *);
 struct page *get_read_data_page(struct inode *, pgoff_t, int);
 struct page *find_data_page(struct inode *, pgoff_t);
 struct page *get_lock_data_page(struct inode *, pgoff_t);
 struct page *get_new_data_page(struct inode *, struct page *, pgoff_t, bool);
 int do_write_data_page(struct f2fs_io_info *);
 int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *, u64, u64);
-void init_extent_cache_info(struct f2fs_sb_info *);
-int __init create_extent_cache(void);
-void destroy_extent_cache(void);
 void f2fs_invalidate_page(struct page *, unsigned int, unsigned int);
 int f2fs_release_page(struct page *, gfp_t);
 
@@ -1976,6 +1968,20 @@ unsigned long f2fs_shrink_scan(struct shrinker *, struct shrink_control *);
 void f2fs_join_shrinker(struct f2fs_sb_info *);
 void f2fs_leave_shrinker(struct f2fs_sb_info *);
 
+/*
+ * extent_cache.c
+ */
+unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
+void f2fs_drop_largest_extent(struct inode *, pgoff_t);
+void f2fs_init_extent_tree(struct inode *, struct f2fs_extent *);
+unsigned int f2fs_destroy_extent_node(struct inode *);
+void f2fs_destroy_extent_tree(struct inode *);
+bool f2fs_lookup_extent_cache(struct inode *, pgoff_t, struct extent_info *);
+void f2fs_update_extent_cache(struct dnode_of_data *);
+void init_extent_cache_info(struct f2fs_sb_info *);
+int __init create_extent_cache(void);
+void destroy_extent_cache(void);
+
 /*
  * crypto support
  */