Ocfs2: Re-access the journal after ocfs2_insert_extent() in dxdir codes.

In ocfs2_dx_dir_rebalance(), we need to rejournal_acess the blocks after
calling ocfs2_insert_extent() since growing an extent tree may trigger
ocfs2_extend_trans(), which makes previous journal_access meaningless.

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>