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

diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 617f81157ac206ee640ed3e370ab041f34aa927e..732e30c570991ac37e2f2bcea47f5d47b699b2d1 100644 (file)
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -1270,7 +1270,8 @@ CheckPointLogicalRewriteHeap(void)
                }
                else
                {
-                       int                     fd = OpenTransientFile(path, O_RDONLY | PG_BINARY, 0);
+                       /* on some operating systems fsyncing a file requires O_RDWR */
+                       int                     fd = OpenTransientFile(path, O_RDWR | PG_BINARY, 0);
 
                        /*
                         * The file cannot vanish due to concurrency since this function