diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 5c206f941aac..9a8153895d20 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -161,95 +161,52 @@ static bool __is_front_mergeable(struct extent_info *cur,
 	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)
+static struct extent_node *__lookup_extent_node(struct rb_root_cached *root,
+			struct extent_node *cached_en, unsigned int fofs)
 {
 	struct rb_node *node = root->rb_root.rb_node;
-	struct rb_entry *re;
+	struct extent_node *en;
+
+	/* check a cached entry */
+	if (cached_en && cached_en->ei.fofs <= fofs &&
+			cached_en->ei.fofs + cached_en->ei.len > fofs)
+		return cached_en;
 
+	/* check rb_tree */
 	while (node) {
-		re = rb_entry(node, struct rb_entry, rb_node);
+		en = rb_entry(node, struct extent_node, rb_node);
 
-		if (ofs < re->ofs)
+		if (fofs < en->ei.fofs)
 			node = node->rb_left;
-		else if (ofs >= re->ofs + re->len)
+		else if (fofs >= en->ei.fofs + en->ei.len)
 			node = node->rb_right;
 		else
-			return re;
+			return en;
 	}
 	return NULL;
 }
 
-static 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;
-}
-
-static 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,
+ * lookup rb entry in position of @fofs 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
+ * @prev_ex: extent before fofs
+ * @next_ex: extent after fofs
+ * @insert_p: insert point for new extent at fofs
  * in order to simplify the insertion after.
  * tree must stay unchanged between lookup and insertion.
  */
-static 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,
+static struct extent_node *__lookup_extent_node_ret(struct rb_root_cached *root,
+				struct extent_node *cached_en,
+				unsigned int fofs,
+				struct extent_node **prev_entry,
+				struct extent_node **next_entry,
 				struct rb_node ***insert_p,
 				struct rb_node **insert_parent,
-				bool force, bool *leftmost)
+				bool *leftmost)
 {
 	struct rb_node **pnode = &root->rb_root.rb_node;
 	struct rb_node *parent = NULL, *tmp_node;
-	struct rb_entry *re = cached_re;
+	struct extent_node *en = cached_en;
 
 	*insert_p = NULL;
 	*insert_parent = NULL;
@@ -259,24 +216,20 @@ static struct rb_entry *f2fs_lookup_rb_tree_ret(struct rb_root_cached *root,
 	if (RB_EMPTY_ROOT(&root->rb_root))
 		return NULL;
 
-	if (re) {
-		if (re->ofs <= ofs && re->ofs + re->len > ofs)
-			goto lookup_neighbors;
-	}
+	if (en && en->ei.fofs <= fofs && en->ei.fofs + en->ei.len > fofs)
+		goto lookup_neighbors;
 
-	if (leftmost)
-		*leftmost = true;
+	*leftmost = true;
 
 	while (*pnode) {
 		parent = *pnode;
-		re = rb_entry(*pnode, struct rb_entry, rb_node);
+		en = rb_entry(*pnode, struct extent_node, rb_node);
 
-		if (ofs < re->ofs) {
+		if (fofs < en->ei.fofs) {
 			pnode = &(*pnode)->rb_left;
-		} else if (ofs >= re->ofs + re->len) {
+		} else if (fofs >= en->ei.fofs + en->ei.len) {
 			pnode = &(*pnode)->rb_right;
-			if (leftmost)
-				*leftmost = false;
+			*leftmost = false;
 		} else {
 			goto lookup_neighbors;
 		}
@@ -285,30 +238,32 @@ static struct rb_entry *f2fs_lookup_rb_tree_ret(struct rb_root_cached *root,
 	*insert_p = pnode;
 	*insert_parent = parent;
 
-	re = rb_entry(parent, struct rb_entry, rb_node);
+	en = rb_entry(parent, struct extent_node, rb_node);
 	tmp_node = parent;
-	if (parent && ofs > re->ofs)
+	if (parent && fofs > en->ei.fofs)
 		tmp_node = rb_next(parent);
-	*next_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
+	*next_entry = rb_entry_safe(tmp_node, struct extent_node, rb_node);
 
 	tmp_node = parent;
-	if (parent && ofs < re->ofs)
+	if (parent && fofs < en->ei.fofs)
 		tmp_node = rb_prev(parent);
-	*prev_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
+	*prev_entry = rb_entry_safe(tmp_node, struct extent_node, rb_node);
 	return NULL;
 
 lookup_neighbors:
-	if (ofs == re->ofs || force) {
+	if (fofs == en->ei.fofs) {
 		/* 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);
+		tmp_node = rb_prev(&en->rb_node);
+		*prev_entry = rb_entry_safe(tmp_node,
+					struct extent_node, rb_node);
 	}
-	if (ofs == re->ofs + re->len - 1 || force) {
+	if (fofs == en->ei.fofs + en->ei.len - 1) {
 		/* 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);
+		tmp_node = rb_next(&en->rb_node);
+		*next_entry = rb_entry_safe(tmp_node,
+					struct extent_node, rb_node);
 	}
-	return re;
+	return en;
 }
 
 static struct kmem_cache *extent_tree_slab;
@@ -523,8 +478,7 @@ static bool __lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
 		goto out;
 	}
 
-	en = (struct extent_node *)f2fs_lookup_rb_tree(&et->root,
-				(struct rb_entry *)et->cached_en, pgofs);
+	en = __lookup_extent_node(&et->root, et->cached_en, pgofs);
 	if (!en)
 		goto out;
 
@@ -598,7 +552,7 @@ static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
 				bool leftmost)
 {
 	struct extent_tree_info *eti = &sbi->extent_tree[et->type];
-	struct rb_node **p;
+	struct rb_node **p = &et->root.rb_root.rb_node;
 	struct rb_node *parent = NULL;
 	struct extent_node *en = NULL;
 
@@ -610,8 +564,21 @@ static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
 
 	leftmost = true;
 
-	p = f2fs_lookup_rb_tree_for_insert(sbi, &et->root, &parent,
-						ei->fofs, &leftmost);
+	/* look up extent_node in the rb tree */
+	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;
+			leftmost = false;
+		} else {
+			f2fs_bug_on(sbi, 1);
+		}
+	}
+
 do_insert:
 	en = __attach_extent_node(sbi, et, ei, parent, p, leftmost);
 	if (!en)
@@ -670,11 +637,10 @@ static void __update_extent_tree_range(struct inode *inode,
 	}
 
 	/* 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,
+	en = __lookup_extent_node_ret(&et->root,
+					et->cached_en, fofs,
+					&prev_en, &next_en,
+					&insert_p, &insert_parent,
 					&leftmost);
 	if (!en)
 		en = next_en;
@@ -812,12 +778,11 @@ void f2fs_update_read_extent_tree_range_compressed(struct inode *inode,
 
 	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);
+	en = __lookup_extent_node_ret(&et->root,
+					et->cached_en, fofs,
+					&prev_en, &next_en,
+					&insert_p, &insert_parent,
+					&leftmost);
 	if (en)
 		goto unlock_out;
 
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 6e04fea9c34f..90a67feddcdc 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -620,12 +620,6 @@ enum extent_type {
 	NR_EXTENT_CACHES,
 };
 
-struct rb_entry {
-	struct rb_node rb_node;		/* rb node located in rb-tree */
-	unsigned int ofs;		/* start offset of the entry */
-	unsigned int len;		/* length of the entry */
-};
-
 struct extent_info {
 	unsigned int fofs;		/* start offset in a file */
 	unsigned int len;		/* length of the extent */
