pg_basebackup: Skip a few more fsyncs if --no-sync is specified.

This is mostly interesting for running the regression tests on machines with
slow / overloaded IO.

Discussion: https://postgr.es/m/20220119041646.rhuo3youiqxqjmo2@alap3.anarazel.de

src/bin/pg_basebackup/pg_basebackup.c

@@ -2201,9 +2201,21 @@ BaseBackup(void)
 		snprintf(tmp_filename, MAXPGPATH, "%s/backup_manifest.tmp", basedir);
 		snprintf(filename, MAXPGPATH, "%s/backup_manifest", basedir);
 
-		/* durable_rename emits its own log message in case of failure */
-		if (durable_rename(tmp_filename, filename) != 0)
-			exit(1);
+		if (do_sync)
+		{
+			/* durable_rename emits its own log message in case of failure */
+			if (durable_rename(tmp_filename, filename) != 0)
+				exit(1);
+		}
+		else
+		{
+			if (rename(tmp_filename, filename) != 0)
+			{
+				pg_log_error("could not rename file \"%s\" to \"%s\": %m",
+							 tmp_filename, filename);
+				exit(1);
+			}
+		}
 	}
 
 	if (verbose)

src/bin/pg_basebackup/walmethods.c

@@ -445,7 +445,17 @@ dir_close(Walfile f, WalCloseMethod method)
 			snprintf(tmppath2, sizeof(tmppath2), "%s/%s",
 					 dir_data->basedir, filename2);
 			pg_free(filename2);
-			r = durable_rename(tmppath, tmppath2);
+			if (dir_data->sync)
+				r = durable_rename(tmppath, tmppath2);
+			else
+			{
+				if (rename(tmppath, tmppath2) != 0)
+				{
+					pg_log_error("could not rename file \"%s\" to \"%s\": %m",
+								 tmppath, tmppath2);
+					r = -1;
+				}
+			}
 		}
 		else if (method == CLOSE_UNLINK)
 		{