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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __DRBD_PROTOCOL_H
3#define __DRBD_PROTOCOL_H
4
5enum drbd_packet {
6 /* receiver (data socket) */
7 P_DATA = 0x00,
8 P_DATA_REPLY = 0x01, /* Response to P_DATA_REQUEST */
9 P_RS_DATA_REPLY = 0x02, /* Response to P_RS_DATA_REQUEST */
10 P_BARRIER = 0x03,
11 P_BITMAP = 0x04,
12 P_BECOME_SYNC_TARGET = 0x05,
13 P_BECOME_SYNC_SOURCE = 0x06,
14 P_UNPLUG_REMOTE = 0x07, /* Used at various times to hint the peer */
15 P_DATA_REQUEST = 0x08, /* Used to ask for a data block */
16 P_RS_DATA_REQUEST = 0x09, /* Used to ask for a data block for resync */
17 P_SYNC_PARAM = 0x0a,
18 P_PROTOCOL = 0x0b,
19 P_UUIDS = 0x0c,
20 P_SIZES = 0x0d,
21 P_STATE = 0x0e,
22 P_SYNC_UUID = 0x0f,
23 P_AUTH_CHALLENGE = 0x10,
24 P_AUTH_RESPONSE = 0x11,
25 P_STATE_CHG_REQ = 0x12,
26
27 /* (meta socket) */
28 P_PING = 0x13,
29 P_PING_ACK = 0x14,
30 P_RECV_ACK = 0x15, /* Used in protocol B */
31 P_WRITE_ACK = 0x16, /* Used in protocol C */
32 P_RS_WRITE_ACK = 0x17, /* Is a P_WRITE_ACK, additionally call set_in_sync(). */
33 P_SUPERSEDED = 0x18, /* Used in proto C, two-primaries conflict detection */
34 P_NEG_ACK = 0x19, /* Sent if local disk is unusable */
35 P_NEG_DREPLY = 0x1a, /* Local disk is broken... */
36 P_NEG_RS_DREPLY = 0x1b, /* Local disk is broken... */
37 P_BARRIER_ACK = 0x1c,
38 P_STATE_CHG_REPLY = 0x1d,
39
40 /* "new" commands, no longer fitting into the ordering scheme above */
41
42 P_OV_REQUEST = 0x1e, /* data socket */
43 P_OV_REPLY = 0x1f,
44 P_OV_RESULT = 0x20, /* meta socket */
45 P_CSUM_RS_REQUEST = 0x21, /* data socket */
46 P_RS_IS_IN_SYNC = 0x22, /* meta socket */
47 P_SYNC_PARAM89 = 0x23, /* data socket, protocol version 89 replacement for P_SYNC_PARAM */
48 P_COMPRESSED_BITMAP = 0x24, /* compressed or otherwise encoded bitmap transfer */
49 /* P_CKPT_FENCE_REQ = 0x25, * currently reserved for protocol D */
50 /* P_CKPT_DISABLE_REQ = 0x26, * currently reserved for protocol D */
51 P_DELAY_PROBE = 0x27, /* is used on BOTH sockets */
52 P_OUT_OF_SYNC = 0x28, /* Mark as out of sync (Outrunning), data socket */
53 P_RS_CANCEL = 0x29, /* meta: Used to cancel RS_DATA_REQUEST packet by SyncSource */
54 P_CONN_ST_CHG_REQ = 0x2a, /* data sock: Connection wide state request */
55 P_CONN_ST_CHG_REPLY = 0x2b, /* meta sock: Connection side state req reply */
56 P_RETRY_WRITE = 0x2c, /* Protocol C: retry conflicting write request */
57 P_PROTOCOL_UPDATE = 0x2d, /* data sock: is used in established connections */
58 /* 0x2e to 0x30 reserved, used in drbd 9 */
59
60 /* REQ_DISCARD. We used "discard" in different contexts before,
61 * which is why I chose TRIM here, to disambiguate. */
62 P_TRIM = 0x31,
63
64 /* Only use these two if both support FF_THIN_RESYNC */
65 P_RS_THIN_REQ = 0x32, /* Request a block for resync or reply P_RS_DEALLOCATED */
66 P_RS_DEALLOCATED = 0x33, /* Contains only zeros on sync source node */
67
68 /* REQ_WRITE_SAME.
69 * On a receiving side without REQ_WRITE_SAME,
70 * we may fall back to an opencoded loop instead. */
71 P_WSAME = 0x34,
72
73 P_MAY_IGNORE = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
74 P_MAX_OPT_CMD = 0x101,
75
76 /* special command ids for handshake */
77
78 P_INITIAL_META = 0xfff1, /* First Packet on the MetaSock */
79 P_INITIAL_DATA = 0xfff2, /* First Packet on the Socket */
80
81 P_CONNECTION_FEATURES = 0xfffe /* FIXED for the next century! */
82};
83
84#ifndef __packed
85#define __packed __attribute__((packed))
86#endif
87
88/* This is the layout for a packet on the wire.
89 * The byteorder is the network byte order.
90 * (except block_id and barrier fields.
91 * these are pointers to local structs
92 * and have no relevance for the partner,
93 * which just echoes them as received.)
94 *
95 * NOTE that the payload starts at a long aligned offset,
96 * regardless of 32 or 64 bit arch!
97 */
98struct p_header80 {
99 u32 magic;
100 u16 command;
101 u16 length; /* bytes of data after this header */
102} __packed;
103
104/* Header for big packets, Used for data packets exceeding 64kB */
105struct p_header95 {
106 u16 magic; /* use DRBD_MAGIC_BIG here */
107 u16 command;
108 u32 length;
109} __packed;
110
111struct p_header100 {
112 u32 magic;
113 u16 volume;
114 u16 command;
115 u32 length;
116 u32 pad;
117} __packed;
118
119/* These defines must not be changed without changing the protocol version.
120 * New defines may only be introduced together with protocol version bump or
121 * new protocol feature flags.
122 */
123#define DP_HARDBARRIER 1 /* no longer used */
124#define DP_RW_SYNC 2 /* equals REQ_SYNC */
125#define DP_MAY_SET_IN_SYNC 4
126#define DP_UNPLUG 8 /* not used anymore */
127#define DP_FUA 16 /* equals REQ_FUA */
128#define DP_FLUSH 32 /* equals REQ_PREFLUSH */
129#define DP_DISCARD 64 /* equals REQ_DISCARD */
130#define DP_SEND_RECEIVE_ACK 128 /* This is a proto B write request */
131#define DP_SEND_WRITE_ACK 256 /* This is a proto C write request */
132#define DP_WSAME 512 /* equiv. REQ_WRITE_SAME */
133
134struct p_data {
135 u64 sector; /* 64 bits sector number */
136 u64 block_id; /* to identify the request in protocol B&C */
137 u32 seq_num;
138 u32 dp_flags;
139} __packed;
140
141struct p_trim {
142 struct p_data p_data;
143 u32 size; /* == bio->bi_size */
144} __packed;
145
146struct p_wsame {
147 struct p_data p_data;
148 u32 size; /* == bio->bi_size */
149} __packed;
150
151/*
152 * commands which share a struct:
153 * p_block_ack:
154 * P_RECV_ACK (proto B), P_WRITE_ACK (proto C),
155 * P_SUPERSEDED (proto C, two-primaries conflict detection)
156 * p_block_req:
157 * P_DATA_REQUEST, P_RS_DATA_REQUEST
158 */
159struct p_block_ack {
160 u64 sector;
161 u64 block_id;
162 u32 blksize;
163 u32 seq_num;
164} __packed;
165
166struct p_block_req {
167 u64 sector;
168 u64 block_id;
169 u32 blksize;
170 u32 pad; /* to multiple of 8 Byte */
171} __packed;
172
173/*
174 * commands with their own struct for additional fields:
175 * P_CONNECTION_FEATURES
176 * P_BARRIER
177 * P_BARRIER_ACK
178 * P_SYNC_PARAM
179 * ReportParams
180 */
181
182/* supports TRIM/DISCARD on the "wire" protocol */
183#define DRBD_FF_TRIM 1
184
185/* Detect all-zeros during resync, and rather TRIM/UNMAP/DISCARD those blocks
186 * instead of fully allocate a supposedly thin volume on initial resync */
187#define DRBD_FF_THIN_RESYNC 2
188
189/* supports REQ_WRITE_SAME on the "wire" protocol.
190 * Note: this flag is overloaded,
191 * its presence also
192 * - indicates support for 128 MiB "batch bios",
193 * max discard size of 128 MiB
194 * instead of 4M before that.
195 * - indicates that we exchange additional settings in p_sizes
196 * drbd_send_sizes()/receive_sizes()
197 */
198#define DRBD_FF_WSAME 4
199
200struct p_connection_features {
201 u32 protocol_min;
202 u32 feature_flags;
203 u32 protocol_max;
204
205 /* should be more than enough for future enhancements
206 * for now, feature_flags and the reserved array shall be zero.
207 */
208
209 u32 _pad;
210 u64 reserved[7];
211} __packed;
212
213struct p_barrier {
214 u32 barrier; /* barrier number _handle_ only */
215 u32 pad; /* to multiple of 8 Byte */
216} __packed;
217
218struct p_barrier_ack {
219 u32 barrier;
220 u32 set_size;
221} __packed;
222
223struct p_rs_param {
224 u32 resync_rate;
225
226 /* Since protocol version 88 and higher. */
227 char verify_alg[0];
228} __packed;
229
230struct p_rs_param_89 {
231 u32 resync_rate;
232 /* protocol version 89: */
233 char verify_alg[SHARED_SECRET_MAX];
234 char csums_alg[SHARED_SECRET_MAX];
235} __packed;
236
237struct p_rs_param_95 {
238 u32 resync_rate;
239 char verify_alg[SHARED_SECRET_MAX];
240 char csums_alg[SHARED_SECRET_MAX];
241 u32 c_plan_ahead;
242 u32 c_delay_target;
243 u32 c_fill_target;
244 u32 c_max_rate;
245} __packed;
246
247enum drbd_conn_flags {
248 CF_DISCARD_MY_DATA = 1,
249 CF_DRY_RUN = 2,
250};
251
252struct p_protocol {
253 u32 protocol;
254 u32 after_sb_0p;
255 u32 after_sb_1p;
256 u32 after_sb_2p;
257 u32 conn_flags;
258 u32 two_primaries;
259
260 /* Since protocol version 87 and higher. */
261 char integrity_alg[0];
262
263} __packed;
264
265struct p_uuids {
266 u64 uuid[UI_EXTENDED_SIZE];
267} __packed;
268
269struct p_rs_uuid {
270 u64 uuid;
271} __packed;
272
273/* optional queue_limits if (agreed_features & DRBD_FF_WSAME)
274 * see also struct queue_limits, as of late 2015 */
275struct o_qlim {
276 /* we don't need it yet, but we may as well communicate it now */
277 u32 physical_block_size;
278
279 /* so the original in struct queue_limits is unsigned short,
280 * but I'd have to put in padding anyways. */
281 u32 logical_block_size;
282
283 /* One incoming bio becomes one DRBD request,
284 * which may be translated to several bio on the receiving side.
285 * We don't need to communicate chunk/boundary/segment ... limits.
286 */
287
288 /* various IO hints may be useful with "diskless client" setups */
289 u32 alignment_offset;
290 u32 io_min;
291 u32 io_opt;
292
293 /* We may need to communicate integrity stuff at some point,
294 * but let's not get ahead of ourselves. */
295
296 /* Backend discard capabilities.
297 * Receiving side uses "blkdev_issue_discard()", no need to communicate
298 * more specifics. If the backend cannot do discards, the DRBD peer
299 * may fall back to blkdev_issue_zeroout().
300 */
301 u8 discard_enabled;
302 u8 discard_zeroes_data;
303 u8 write_same_capable;
304 u8 _pad;
305} __packed;
306
307struct p_sizes {
308 u64 d_size; /* size of disk */
309 u64 u_size; /* user requested size */
310 u64 c_size; /* current exported size */
311 u32 max_bio_size; /* Maximal size of a BIO */
312 u16 queue_order_type; /* not yet implemented in DRBD*/
313 u16 dds_flags; /* use enum dds_flags here. */
314
315 /* optional queue_limits if (agreed_features & DRBD_FF_WSAME) */
316 struct o_qlim qlim[0];
317} __packed;
318
319struct p_state {
320 u32 state;
321} __packed;
322
323struct p_req_state {
324 u32 mask;
325 u32 val;
326} __packed;
327
328struct p_req_state_reply {
329 u32 retcode;
330} __packed;
331
332struct p_drbd06_param {
333 u64 size;
334 u32 state;
335 u32 blksize;
336 u32 protocol;
337 u32 version;
338 u32 gen_cnt[5];
339 u32 bit_map_gen[5];
340} __packed;
341
342struct p_block_desc {
343 u64 sector;
344 u32 blksize;
345 u32 pad; /* to multiple of 8 Byte */
346} __packed;
347
348/* Valid values for the encoding field.
349 * Bump proto version when changing this. */
350enum drbd_bitmap_code {
351 /* RLE_VLI_Bytes = 0,
352 * and other bit variants had been defined during
353 * algorithm evaluation. */
354 RLE_VLI_Bits = 2,
355};
356
357struct p_compressed_bm {
358 /* (encoding & 0x0f): actual encoding, see enum drbd_bitmap_code
359 * (encoding & 0x80): polarity (set/unset) of first runlength
360 * ((encoding >> 4) & 0x07): pad_bits, number of trailing zero bits
361 * used to pad up to head.length bytes
362 */
363 u8 encoding;
364
365 u8 code[0];
366} __packed;
367
368struct p_delay_probe93 {
369 u32 seq_num; /* sequence number to match the two probe packets */
370 u32 offset; /* usecs the probe got sent after the reference time point */
371} __packed;
372
373/*
374 * Bitmap packets need to fit within a single page on the sender and receiver,
375 * so we are limited to 4 KiB (and not to PAGE_SIZE, which can be bigger).
376 */
377#define DRBD_SOCKET_BUFFER_SIZE 4096
378
379#endif /* __DRBD_PROTOCOL_H */