1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2#ifndef _LINUX_CACHEFILES_H
3#define _LINUX_CACHEFILES_H
4
5#include <linux/types.h>
6#include <linux/ioctl.h>
7
8/*
9 * Fscache ensures that the maximum length of cookie key is 255. The volume key
10 * is controlled by netfs, and generally no bigger than 255.
11 */
12#define CACHEFILES_MSG_MAX_SIZE 1024
13
14enum cachefiles_opcode {
15 CACHEFILES_OP_OPEN,
16 CACHEFILES_OP_CLOSE,
17 CACHEFILES_OP_READ,
18};
19
20/*
21 * Message Header
22 *
23 * @msg_id a unique ID identifying this message
24 * @opcode message type, CACHEFILE_OP_*
25 * @len message length, including message header and following data
26 * @object_id a unique ID identifying a cache file
27 * @data message type specific payload
28 */
29struct cachefiles_msg {
30 __u32 msg_id;
31 __u32 opcode;
32 __u32 len;
33 __u32 object_id;
34 __u8 data[];
35};
36
37/*
38 * @data contains the volume_key followed directly by the cookie_key. volume_key
39 * is a NUL-terminated string; @volume_key_size indicates the size of the volume
40 * key in bytes. cookie_key is binary data, which is netfs specific;
41 * @cookie_key_size indicates the size of the cookie key in bytes.
42 *
43 * @fd identifies an anon_fd referring to the cache file.
44 */
45struct cachefiles_open {
46 __u32 volume_key_size;
47 __u32 cookie_key_size;
48 __u32 fd;
49 __u32 flags;
50 __u8 data[];
51};
52
53/*
54 * @off indicates the starting offset of the requested file range
55 * @len indicates the length of the requested file range
56 */
57struct cachefiles_read {
58 __u64 off;
59 __u64 len;
60};
61
62/*
63 * Reply for READ request
64 * @arg for this ioctl is the @id field of READ request.
65 */
66#define CACHEFILES_IOC_READ_COMPLETE _IOW(0x98, 1, int)
67
68#endif