DAOS-18597 bio: allow SPDK reinitialization

src/bio/bio_xstream.c

@@ -1710,6 +1710,19 @@ bio_xsctxt_init_by_config(struct common_cp_arg *cp_arg)
 		return -DER_NOMEM;
 	}
 
+	/**
+	 * Initially, this was called internally spdk_subsystem_load_config() -> ... ->
+	 * spdk_rpc_initialize(). However, since commit
+	 * https://github.com/spdk/spdk/commit/fba209c7324a11b9230533144c02e7a66bc738ea (>=v24.01)
+	 * SPDK_RPC_STARTUP has become the initial value of the underlying global variable and it
+	 * is no longer reset automatically. This makes no difference for applications that
+	 * initialize SPDK only once during the lifetime of the process. But some BIO module
+	 * consumers—such as DDB—expect to be able to initialize, finalize, and then reinitialize
+	 * SPDK multiple times within the same process, for example when inspecting multiple pools
+	 * sequentially. For those use cases, the RPC state must now be reset explicitly.
+	 */
+	spdk_rpc_set_state(SPDK_RPC_STARTUP);
+
 	D_ALLOC_PTR(init_arg);
 	if (init_arg == NULL) {
 		free(json_data);