Abort online reencryption for misconfigured devices.

Hard abort is justified here. The online reencryption on
data devices that do not support O_DIRECT io flag is
dangerous and leads to data corruption. This should be
impossible to hit due to a patch that handles it
in initialization phase. Better safe than sorry.

lib/luks2/luks2_reencrypt.c

@@ -4230,9 +4230,14 @@ int crypt_reencrypt_run(
 
 	log_dbg(cd, "Resuming LUKS2 reencryption.");
 
-	if (rh->online && reencrypt_init_device_stack(cd, rh)) {
-		log_err(cd, _("Failed to initialize reencryption device stack."));
-		return -EINVAL;
+	if (rh->online) {
+		/* This is last resort to avoid data corruption. Abort is justified here. */
+		assert(device_direct_io(crypt_data_device(cd)));
+
+		if (reencrypt_init_device_stack(cd, rh)) {
+			log_err(cd, _("Failed to initialize reencryption device stack."));
+			return -EINVAL;
+		}
 	}
 
 	log_dbg(cd, "Progress %" PRIu64 ", device_size %" PRIu64, rh->progress, rh->device_size);