1 files changed, 50 insertions, 0 deletions
diff --git a/include/uapi/linux/cachefiles.h b/include/uapi/linux/cachefiles.h
new file mode 100644
index 000000000000..521f2fe4fe9c
--- /dev/null
+++ b/include/uapi/linux/cachefiles.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _LINUX_CACHEFILES_H
+#define _LINUX_CACHEFILES_H
+
+#include <linux/types.h>
+
+/*
+ * Fscache ensures that the maximum length of cookie key is 255. The volume key
+ * is controlled by netfs, and generally no bigger than 255.
+ */
+#define CACHEFILES_MSG_MAX_SIZE	1024
+
+enum cachefiles_opcode {
+	CACHEFILES_OP_OPEN,
+};
+
+/*
+ * Message Header
+ *
+ * @msg_id	a unique ID identifying this message
+ * @opcode	message type, CACHEFILE_OP_*
+ * @len		message length, including message header and following data
+ * @object_id	a unique ID identifying a cache file
+ * @data	message type specific payload
+ */
+struct cachefiles_msg {
+	__u32 msg_id;
+	__u32 opcode;
+	__u32 len;
+	__u32 object_id;
+	__u8  data[];
+};
+
+/*
+ * @data contains the volume_key followed directly by the cookie_key. volume_key
+ * is a NUL-terminated string; @volume_key_size indicates the size of the volume
+ * key in bytes. cookie_key is binary data, which is netfs specific;
+ * @cookie_key_size indicates the size of the cookie key in bytes.
+ *
+ * @fd identifies an anon_fd referring to the cache file.
+ */
+struct cachefiles_open {
+	__u32 volume_key_size;
+	__u32 cookie_key_size;
+	__u32 fd;
+	__u32 flags;
+	__u8  data[];
+};
+
+#endif