ocfs2: fix some inconsistency problems caused by jbd2_journal_restart()

I found that function jbd2_journal_restart() is called some places in ocfs2 without keeping things consistently before. However, jbd2_journal_restart() may commit the handle's transaction and restart another one. If the first transaction is committed successfully while another not, it may cause filesystem inconsistency or read only. This is an effort to fix this kind of problems.

Any comments are appreciated, thanks!