f2fs: allocate the extent_cache by default

Let's allocate it to remove the runtime complexity.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/extent_cache.c

@@ -47,20 +47,23 @@ static bool __may_read_extent_tree(struct inode *inode)
 	return S_ISREG(inode->i_mode);
 }
 
-static bool __may_extent_tree(struct inode *inode, enum extent_type type)
+static bool __init_may_extent_tree(struct inode *inode, enum extent_type type)
 {
-	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	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(&sbi->s_list))
+	if (list_empty(&F2FS_I_SB(inode)->s_list))
 		return false;
 
-	if (type == EX_READ)
-		return __may_read_extent_tree(inode);
-	return false;
+	return __init_may_extent_tree(inode, type);
 }
 
 static void __try_update_largest_extent(struct extent_tree *et,
@@ -439,20 +442,18 @@ static void __drop_largest_extent(struct extent_tree *et,
 	}
 }
 
-/* return true, if inode page is changed */
-static void __f2fs_init_extent_tree(struct inode *inode, struct page *ipage,
-							enum extent_type type)
+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[type];
-	struct f2fs_extent *i_ext = ipage ? &F2FS_INODE(ipage)->i_ext : NULL;
+	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, type)) {
+	if (!__may_extent_tree(inode, EX_READ)) {
 		/* drop largest read extent */
-		if (type == EX_READ && i_ext && i_ext->len) {
+		if (i_ext && i_ext->len) {
 			f2fs_wait_on_page_writeback(ipage, NODE, true, true);
 			i_ext->len = 0;
 			set_page_dirty(ipage);
@@ -460,13 +461,11 @@ static void __f2fs_init_extent_tree(struct inode *inode, struct page *ipage,
 		goto out;
 	}
 
-	et = __grab_extent_tree(inode, type);
+	et = __grab_extent_tree(inode, EX_READ);
 
 	if (!i_ext || !i_ext->len)
 		goto out;
 
-	BUG_ON(type != EX_READ);
-
 	get_read_extent_info(&ei, i_ext);
 
 	write_lock(&et->lock);
@@ -486,14 +485,15 @@ static void __f2fs_init_extent_tree(struct inode *inode, struct page *ipage,
 unlock_out:
 	write_unlock(&et->lock);
 out:
-	if (type == EX_READ && !F2FS_I(inode)->extent_tree[EX_READ])
+	if (!F2FS_I(inode)->extent_tree[EX_READ])
 		set_inode_flag(inode, FI_NO_EXTENT);
 }
 
-void f2fs_init_extent_tree(struct inode *inode, struct page *ipage)
+void f2fs_init_extent_tree(struct inode *inode)
 {
 	/* initialize read cache */
-	__f2fs_init_extent_tree(inode, ipage, EX_READ);
+	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,

fs/f2fs/f2fs.h

@@ -4150,7 +4150,7 @@ struct rb_entry *f2fs_lookup_rb_tree_ret(struct rb_root_cached *root,
 		bool force, bool *leftmost);
 bool f2fs_check_rb_tree_consistence(struct f2fs_sb_info *sbi,
 				struct rb_root_cached *root, bool check_key);
-void f2fs_init_extent_tree(struct inode *inode, struct page *ipage);
+void f2fs_init_extent_tree(struct inode *inode);
 void f2fs_drop_extent_tree(struct inode *inode);
 void f2fs_destroy_extent_node(struct inode *inode);
 void f2fs_destroy_extent_tree(struct inode *inode);
@@ -4159,6 +4159,7 @@ int __init f2fs_create_extent_cache(void);
 void f2fs_destroy_extent_cache(void);
 
 /* read extent cache ops */
+void f2fs_init_read_extent_tree(struct inode *inode, struct page *ipage);
 bool f2fs_lookup_read_extent_cache(struct inode *inode, pgoff_t pgofs,
 			struct extent_info *ei);
 void f2fs_update_read_extent_cache(struct dnode_of_data *dn);

fs/f2fs/inode.c

@@ -392,8 +392,6 @@ static int do_read_inode(struct inode *inode)
 	fi->i_pino = le32_to_cpu(ri->i_pino);
 	fi->i_dir_level = ri->i_dir_level;
 
-	f2fs_init_extent_tree(inode, node_page);
-
 	get_inline_info(inode, ri);
 
 	fi->i_extra_isize = f2fs_has_extra_attr(inode) ?
@@ -479,6 +477,10 @@ static int do_read_inode(struct inode *inode)
 	}
 
 	init_idisk_time(inode);
+
+	/* Need all the flag bits */
+	f2fs_init_read_extent_tree(inode, node_page);
+
 	f2fs_put_page(node_page, 1);
 
 	stat_inc_inline_xattr(inode);

fs/f2fs/namei.c

@@ -284,8 +284,6 @@ static struct inode *f2fs_new_inode(struct user_namespace *mnt_userns,
 	}
 	F2FS_I(inode)->i_inline_xattr_size = xattr_size;
 
-	f2fs_init_extent_tree(inode, NULL);
-
 	F2FS_I(inode)->i_flags =
 		f2fs_mask_flags(mode, F2FS_I(dir)->i_flags & F2FS_FL_INHERITED);
 
@@ -311,6 +309,8 @@ static struct inode *f2fs_new_inode(struct user_namespace *mnt_userns,
 
 	f2fs_set_inode_flags(inode);
 
+	f2fs_init_extent_tree(inode);
+
 	trace_f2fs_new_inode(inode, 0);
 	return inode;