MDEV-30114 Incremental prepare fails when innodb_undo_tablespaces > 0

- Mariabackup fails to open the undo tablespaces while applying delta
files to the corresponding data file. Mariabackup opens the
undo tablespaces first time in srv_undo_tablespaces_init() and does
tries to open the undo tablespaces in xtrabackup_apply_deltas() with
conflicting mode and leads to the failure.

- Mariabackup should close the undo tablespaces before applying
the incremental delta files.

1 files changed, 20 insertions, 0 deletions

diff --git a/extra/mariabackup/xtrabackup.cc b/extra/mariabackup/xtrabackup.cc
index 3f7dec5ceda..d41321e9bb9 100644
--- a/extra/mariabackup/xtrabackup.cc
+++ b/extra/mariabackup/xtrabackup.cc
@@ -3799,6 +3799,21 @@ func_exit:
 	return error;
 }
 
+/** Close all undo tablespaces while applying incremental delta */
+static void xb_close_undo_tablespaces()
+{
+  if (srv_undo_space_id_start == 0)
+    return;
+  for (ulint space_id= srv_undo_space_id_start;
+       space_id < srv_undo_space_id_start + srv_undo_tablespaces_open;
+       space_id++)
+  {
+     fil_space_t *space= fil_space_get(space_id);
+     ut_ad(space);
+     space->close();
+  }
+}
+
 /****************************************************************************
 Populates the tablespace memory cache by scanning for and opening data files.
 @returns DB_SUCCESS or error code.*/
@@ -3861,6 +3876,11 @@ xb_load_tablespaces()
 	if (err != DB_SUCCESS) {
 		return(err);
 	}
+
+	if (srv_operation == SRV_OPERATION_RESTORE_DELTA) {
+		xb_close_undo_tablespaces();
+	}
+
 	DBUG_MARIABACKUP_EVENT("after_load_tablespaces", 0);
 	return(DB_SUCCESS);
 }