XLogWrite uses palloc within a critical section

Hello.

I happened to see the following in XLogWrite.

> ereport(PANIC,
> (errcode_for_file_access(),
> errmsg("could not seek in log file %s to offset %u: %m",
> XLogFileNameP(ThisTimeLineID, openLogSegNo),
> startoffset)));

where XLogFileNameP calls palloc within, and it is within a
critical section there. So it ends with assertion failure hiding
the PANIC message. We should use XLogFileName instead. The
problem has existed at least since 9.3. The code is frequently
revised so the patch needed to vary into four files.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center