f2fs: initialize extent tree with on-disk extent info of inode

With normal extent info cache, we records largest extent mapping between logical
block and physical block into extent info, and we persist extent info in on-disk
inode.

When we enable extent tree cache, if extent info of on-disk inode is exist, and
the extent is not a small fragmented mapping extent. We'd better to load the
extent info into extent tree cache when inode is loaded. By this way we can have
more chance to hit extent tree cache rather than taking more time to read dnode
page for block address.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -572,6 +572,39 @@ static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
 	return count - et->count;
 }
 
+static 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 (le32_to_cpu(i_ext->len) < F2FS_MIN_EXTENT_LEN)
+		return;
+
+	et = __grab_extent_tree(inode);
+
+	write_lock(&et->lock);
+	if (et->count)
+		goto out;
+
+	set_extent_info(&ei, le32_to_cpu(i_ext->fofs),
+		le32_to_cpu(i_ext->blk), le32_to_cpu(i_ext->len));
+
+	en = __insert_extent_tree(sbi, et, &ei, NULL);
+	if (en) {
+		et->cached_en = en;
+
+		spin_lock(&sbi->extent_lock);
+		list_add_tail(&en->list, &sbi->extent_list);
+		spin_unlock(&sbi->extent_lock);
+	}
+out:
+	write_unlock(&et->lock);
+	atomic_dec(&et->refcount);
+}
+
 static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
 							struct extent_info *ei)
 {
@@ -782,6 +815,16 @@ void f2fs_destroy_extent_tree(struct inode *inode)
 	return;
 }
 
+void f2fs_init_extent_cache(struct inode *inode, struct f2fs_extent *i_ext)
+{
+	if (test_opt(F2FS_I_SB(inode), EXTENT_CACHE))
+		f2fs_init_extent_tree(inode, i_ext);
+
+	write_lock(&F2FS_I(inode)->ext_lock);
+	get_extent_info(&F2FS_I(inode)->ext, *i_ext);
+	write_unlock(&F2FS_I(inode)->ext_lock);
+}
+
 static bool f2fs_lookup_extent_cache(struct inode *inode, pgoff_t pgofs,
 							struct extent_info *ei)
 {

fs/f2fs/f2fs.h

@@ -1596,6 +1596,7 @@ int reserve_new_block(struct dnode_of_data *);
 int f2fs_reserve_block(struct dnode_of_data *, pgoff_t);
 void f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
 void f2fs_destroy_extent_tree(struct inode *);
+void f2fs_init_extent_cache(struct inode *, struct f2fs_extent *);
 void f2fs_update_extent_cache(struct dnode_of_data *);
 struct page *find_data_page(struct inode *, pgoff_t, bool);
 struct page *get_lock_data_page(struct inode *, pgoff_t);

fs/f2fs/inode.c

@@ -137,9 +137,7 @@ 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;
 
-	write_lock(&fi->ext_lock);
-	get_extent_info(&fi->ext, ri->i_ext);
-	write_unlock(&fi->ext_lock);
+	f2fs_init_extent_cache(inode, &ri->i_ext);
 
 	get_inline_info(fi, ri);