xref: /linux/include/uapi/linux/nbd.h (revision 26bb0d3f38a764b743a3ad5c8b6e5b5044d7ceb4)
1 /* SPDX-License-Identifier: GPL-1.0+ WITH Linux-syscall-note */
2 /*
3  * 1999 Copyright (C) Pavel Machek, pavel@ucw.cz. This code is GPL.
4  * 1999/11/04 Copyright (C) 1999 VMware, Inc. (Regis "HPReg" Duchesne)
5  *            Made nbd_end_request() use the io_request_lock
6  * 2001 Copyright (C) Steven Whitehouse
7  *            New nbd_end_request() for compatibility with new linux block
8  *            layer code.
9  * 2003/06/24 Louis D. Langholtz <ldl@aros.net>
10  *            Removed unneeded blksize_bits field from nbd_device struct.
11  *            Cleanup PARANOIA usage & code.
12  * 2004/02/19 Paul Clements
13  *            Removed PARANOIA, plus various cleanup and comments
14  * 2023 Copyright Red Hat
15  *            Link to userspace extensions, favor cookie over handle.
16  */
17 
18 #ifndef _UAPILINUX_NBD_H
19 #define _UAPILINUX_NBD_H
20 
21 #include <linux/types.h>
22 
23 #define NBD_SET_SOCK	_IO( 0xab, 0 )
24 #define NBD_SET_BLKSIZE	_IO( 0xab, 1 )
25 #define NBD_SET_SIZE	_IO( 0xab, 2 )
26 #define NBD_DO_IT	_IO( 0xab, 3 )
27 #define NBD_CLEAR_SOCK	_IO( 0xab, 4 )
28 #define NBD_CLEAR_QUE	_IO( 0xab, 5 )
29 #define NBD_PRINT_DEBUG	_IO( 0xab, 6 )
30 #define NBD_SET_SIZE_BLOCKS	_IO( 0xab, 7 )
31 #define NBD_DISCONNECT  _IO( 0xab, 8 )
32 #define NBD_SET_TIMEOUT _IO( 0xab, 9 )
33 #define NBD_SET_FLAGS   _IO( 0xab, 10)
34 
35 /*
36  * See also https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md
37  * for additional userspace extensions not yet utilized in the kernel module.
38  */
39 
40 enum {
41 	NBD_CMD_READ = 0,
42 	NBD_CMD_WRITE = 1,
43 	NBD_CMD_DISC = 2,
44 	NBD_CMD_FLUSH = 3,
45 	NBD_CMD_TRIM = 4,
46 	/* userspace defines additional extension commands */
47 	NBD_CMD_WRITE_ZEROES = 6,
48 };
49 
50 /* values for flags field, these are server interaction specific. */
51 #define NBD_FLAG_HAS_FLAGS	(1 << 0) /* nbd-server supports flags */
52 #define NBD_FLAG_READ_ONLY	(1 << 1) /* device is read-only */
53 #define NBD_FLAG_SEND_FLUSH	(1 << 2) /* can flush writeback cache */
54 #define NBD_FLAG_SEND_FUA	(1 << 3) /* send FUA (forced unit access) */
55 #define NBD_FLAG_ROTATIONAL	(1 << 4) /* device is rotational */
56 #define NBD_FLAG_SEND_TRIM	(1 << 5) /* send trim/discard */
57 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* supports WRITE_ZEROES */
58 /* there is a gap here to match userspace */
59 #define NBD_FLAG_CAN_MULTI_CONN	(1 << 8)	/* Server supports multiple connections per export. */
60 
61 /* values for cmd flags in the upper 16 bits of request type */
62 #define NBD_CMD_FLAG_FUA	(1 << 16) /* FUA (forced unit access) op */
63 #define NBD_CMD_FLAG_NO_HOLE	(1 << 17) /* Do not punch a hole for WRITE_ZEROES */
64 
65 /* These are client behavior specific flags. */
66 #define NBD_CFLAG_DESTROY_ON_DISCONNECT	(1 << 0) /* delete the nbd device on
67 						    disconnect. */
68 #define NBD_CFLAG_DISCONNECT_ON_CLOSE (1 << 1) /* disconnect the nbd device on
69 						*  close by last opener.
70 						*/
71 
72 /* userspace doesn't need the nbd_device structure */
73 
74 /* These are sent over the network in the request/reply magic fields */
75 
76 #define NBD_REQUEST_MAGIC 0x25609513
77 #define NBD_REPLY_MAGIC 0x67446698
78 /* Do *not* use magics: 0x12560953 0x96744668. */
79 /* magic 0x668e33ef for structured reply not supported by kernel yet */
80 
81 /*
82  * This is the packet used for communication between client and
83  * server. All data are in network byte order.
84  */
85 struct nbd_request {
86 	__be32 magic;	/* NBD_REQUEST_MAGIC	*/
87 	__be32 type;	/* See NBD_CMD_*	*/
88 	union {
89 		__be64 cookie;	/* Opaque identifier for request	*/
90 		char handle[8];	/* older spelling of cookie		*/
91 	};
92 	__be64 from;
93 	__be32 len;
94 } __attribute__((packed));
95 
96 /*
97  * This is the reply packet that nbd-server sends back to the client after
98  * it has completed an I/O request (or an error occurs).
99  */
100 struct nbd_reply {
101 	__be32 magic;		/* NBD_REPLY_MAGIC	*/
102 	__be32 error;		/* 0 = ok, else error	*/
103 	union {
104 		__be64 cookie;	/* Opaque identifier from request	*/
105 		char handle[8];	/* older spelling of cookie		*/
106 	};
107 };
108 #endif /* _UAPILINUX_NBD_H */
109