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 5ba83daf1c6cc4d8dfbca12ff91fece42333f955..9f0b586b5b680fe86f173d0392563ed041a2c008 100644 (file)
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -1278,7 +1278,8 @@ CheckPointLogicalRewriteHeap(void)
        }
        else
        {
-           int         fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
+           /* on some operating systems fsyncing a file requires O_RDWR */
+           int         fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
 
            /*
             * The file cannot vanish due to concurrency since this function