Revert recent changes with durable_rename_excl()

This reverts commits 2c902bb and ccfbd92.  Per buildfarm members
kestrel, rorqual and calliphoridae, the assertions checking that a TLI
history file should not exist when created by a WAL receiver have been
failing, and switching to durable_rename() over durable_rename_excl()
would cause the newest TLI history file to overwrite the existing one.
We need to think harder about such cases, so revert the new logic for
now.

Note that all the failures have been reported in the test
025_stuck_on_old_timeline.

Discussion: https://postgr.es/m/511362.1651116498@sss.pgh.pa.us

1 files changed, 63 insertions, 0 deletions

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index f904f60c086..24704b6a023 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -808,6 +808,69 @@ durable_unlink(const char *fname, int elevel)
 }
 
 /*
+ * durable_rename_excl -- rename a file in a durable manner.
+ *
+ * Similar to durable_rename(), except that this routine tries (but does not
+ * guarantee) not to overwrite the target file.
+ *
+ * Note that a crash in an unfortunate moment can leave you with two links to
+ * the target file.
+ *
+ * Log errors with the caller specified severity.
+ *
+ * On Windows, using a hard link followed by unlink() causes concurrency
+ * issues, while a simple rename() does not cause that, so be careful when
+ * changing the logic of this routine.
+ *
+ * Returns 0 if the operation succeeded, -1 otherwise. Note that errno is not
+ * valid upon return.
+ */
+int
+durable_rename_excl(const char *oldfile, const char *newfile, int elevel)
+{
+	/*
+	 * Ensure that, if we crash directly after the rename/link, a file with
+	 * valid contents is moved into place.
+	 */
+	if (fsync_fname_ext(oldfile, false, false, elevel) != 0)
+		return -1;
+
+#ifdef HAVE_WORKING_LINK
+	if (link(oldfile, newfile) < 0)
+	{
+		ereport(elevel,
+				(errcode_for_file_access(),
+				 errmsg("could not link file \"%s\" to \"%s\": %m",
+						oldfile, newfile)));
+		return -1;
+	}
+	unlink(oldfile);
+#else
+	if (rename(oldfile, newfile) < 0)
+	{
+		ereport(elevel,
+				(errcode_for_file_access(),
+				 errmsg("could not rename file \"%s\" to \"%s\": %m",
+						oldfile, newfile)));
+		return -1;
+	}
+#endif
+
+	/*
+	 * Make change persistent in case of an OS crash, both the new entry and
+	 * its parent directory need to be flushed.
+	 */
+	if (fsync_fname_ext(newfile, false, false, elevel) != 0)
+		return -1;
+
+	/* Same for parent directory */
+	if (fsync_parent_path(newfile, elevel) != 0)
+		return -1;
+
+	return 0;
+}
+
+/*
  * InitFileAccess --- initialize this module during backend startup
  *
  * This is called during either normal or standalone backend start.