Flush logical mapping files with fd opened for read/write at checkpoint
The file descriptor was opened with read-only to fsync a regular file,
which would cause EBADFD errors on some platforms.
This is similar to the recent fix done by
a586cc4b (which was broken by
me with
82a5649), except that I noticed this issue while monitoring the
backend code for similar mistakes. Backpatch to 9.4, as this has been
introduced since logical decoding exists as of
b89e151.
Author: Michael Paquier
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/
20191006045548.GA14532@paquier.xyz
Backpatch-through: 9.4