f2fs: skip unnecessary data writes during fsync

This patch intends to improve the fsync performance by skipping remaining the
recovery information, only when there is no data that we should recover.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 7c652b3..9b888fb 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -133,6 +133,17 @@
 		return ret;
 	}
 
+	/*
+	 * if there is no written data, don't waste time to write recovery info.
+	 */
+	if (!is_inode_flag_set(fi, FI_APPEND_WRITE) &&
+		!exist_written_data(sbi, inode->i_ino, APPEND_INO)) {
+		if (is_inode_flag_set(fi, FI_UPDATE_WRITE) ||
+			exist_written_data(sbi, inode->i_ino, UPDATE_INO))
+			goto flush_out;
+		goto out;
+	}
+
 	/* guarantee free sections for fsync */
 	f2fs_balance_fs(sbi);
 
@@ -188,6 +199,13 @@
 		ret = wait_on_node_pages_writeback(sbi, inode->i_ino);
 		if (ret)
 			goto out;
+
+		/* once recovery info is written, don't need to tack this */
+		remove_dirty_inode(sbi, inode->i_ino, APPEND_INO);
+		clear_inode_flag(fi, FI_APPEND_WRITE);
+flush_out:
+		remove_dirty_inode(sbi, inode->i_ino, UPDATE_INO);
+		clear_inode_flag(fi, FI_UPDATE_WRITE);
 		ret = f2fs_issue_flush(F2FS_SB(inode->i_sb));
 	}
 out: