f2fs: avoid mark_inode_dirty

Let's check inode's dirtiness before calling mark_inode_dirty.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 7ba52a0..db4022f 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -300,7 +300,7 @@
 	set_page_dirty(page);
 
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
-	mark_inode_dirty_sync(dir);
+	f2fs_mark_inode_dirty_sync(dir);
 	f2fs_put_page(page, 1);
 }
 
@@ -452,7 +452,7 @@
 		clear_inode_flag(inode, FI_NEW_INODE);
 	}
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
-	mark_inode_dirty_sync(dir);
+	f2fs_mark_inode_dirty_sync(dir);
 
 	if (F2FS_I(dir)->i_current_depth != current_depth)
 		f2fs_i_depth_write(dir, current_depth);
@@ -704,7 +704,7 @@
 	set_page_dirty(page);
 
 	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
-	mark_inode_dirty_sync(dir);
+	f2fs_mark_inode_dirty_sync(dir);
 
 	if (inode)
 		f2fs_drop_nlink(dir, inode);