1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __DRBD_PROTOCOL_H
3 #define __DRBD_PROTOCOL_H
4
5 enum 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_OP_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 /* 0x35 already claimed in DRBD 9 */
74 P_ZEROES = 0x36, /* data sock: zero-out, WRITE_ZEROES */
75
76 /* 0x40 .. 0x48 already claimed in DRBD 9 */
77
78 P_MAY_IGNORE = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
79 P_MAX_OPT_CMD = 0x101,
80
81 /* special command ids for handshake */
82
83 P_INITIAL_META = 0xfff1, /* First Packet on the MetaSock */
84 P_INITIAL_DATA = 0xfff2, /* First Packet on the Socket */
85
86 P_CONNECTION_FEATURES = 0xfffe /* FIXED for the next century! */
87 };
88
89 #ifndef __packed
90 #define __packed __attribute__((packed))
91 #endif
92
93 /* This is the layout for a packet on the wire.
94 * The byteorder is the network byte order.
95 * (except block_id and barrier fields.
96 * these are pointers to local structs
97 * and have no relevance for the partner,
98 * which just echoes them as received.)
99 *
100 * NOTE that the payload starts at a long aligned offset,
101 * regardless of 32 or 64 bit arch!
102 */
103 struct p_header80 {
104 u32 magic;
105 u16 command;
106 u16 length; /* bytes of data after this header */
107 } __packed;
108
109 /* Header for big packets, Used for data packets exceeding 64kB */
110 struct p_header95 {
111 u16 magic; /* use DRBD_MAGIC_BIG here */
112 u16 command;
113 u32 length;
114 } __packed;
115
116 struct p_header100 {
117 u32 magic;
118 u16 volume;
119 u16 command;
120 u32 length;
121 u32 pad;
122 } __packed;
123
124 /* These defines must not be changed without changing the protocol version.
125 * New defines may only be introduced together with protocol version bump or
126 * new protocol feature flags.
127 */
128 #define DP_HARDBARRIER 1 /* no longer used */
129 #define DP_RW_SYNC 2 /* equals REQ_SYNC */
130 #define DP_MAY_SET_IN_SYNC 4
131 #define DP_UNPLUG 8 /* not used anymore */
132 #define DP_FUA 16 /* equals REQ_FUA */
133 #define DP_FLUSH 32 /* equals REQ_PREFLUSH */
134 #define DP_DISCARD 64 /* equals REQ_OP_DISCARD */
135 #define DP_SEND_RECEIVE_ACK 128 /* This is a proto B write request */
136 #define DP_SEND_WRITE_ACK 256 /* This is a proto C write request */
137 #define DP_WSAME 512 /* equiv. REQ_WRITE_SAME */
138 #define DP_ZEROES 1024 /* equiv. REQ_OP_WRITE_ZEROES */
139
140 /* possible combinations:
141 * REQ_OP_WRITE_ZEROES: DP_DISCARD | DP_ZEROES
142 * REQ_OP_WRITE_ZEROES + REQ_NOUNMAP: DP_ZEROES
143 */
144
145 struct p_data {
146 u64 sector; /* 64 bits sector number */
147 u64 block_id; /* to identify the request in protocol B&C */
148 u32 seq_num;
149 u32 dp_flags;
150 } __packed;
151
152 struct p_trim {
153 struct p_data p_data;
154 u32 size; /* == bio->bi_size */
155 } __packed;
156
157 struct p_wsame {
158 struct p_data p_data;
159 u32 size; /* == bio->bi_size */
160 } __packed;
161
162 /*
163 * commands which share a struct:
164 * p_block_ack:
165 * P_RECV_ACK (proto B), P_WRITE_ACK (proto C),
166 * P_SUPERSEDED (proto C, two-primaries conflict detection)
167 * p_block_req:
168 * P_DATA_REQUEST, P_RS_DATA_REQUEST
169 */
170 struct p_block_ack {
171 u64 sector;
172 u64 block_id;
173 u32 blksize;
174 u32 seq_num;
175 } __packed;
176
177 struct p_block_req {
178 u64 sector;
179 u64 block_id;
180 u32 blksize;
181 u32 pad; /* to multiple of 8 Byte */
182 } __packed;
183
184 /*
185 * commands with their own struct for additional fields:
186 * P_CONNECTION_FEATURES
187 * P_BARRIER
188 * P_BARRIER_ACK
189 * P_SYNC_PARAM
190 * ReportParams
191 */
192
193 /* supports TRIM/DISCARD on the "wire" protocol */
194 #define DRBD_FF_TRIM 1
195
196 /* Detect all-zeros during resync, and rather TRIM/UNMAP/DISCARD those blocks
197 * instead of fully allocate a supposedly thin volume on initial resync */
198 #define DRBD_FF_THIN_RESYNC 2
199
200 /* supports REQ_WRITE_SAME on the "wire" protocol.
201 * Note: this flag is overloaded,
202 * its presence also
203 * - indicates support for 128 MiB "batch bios",
204 * max discard size of 128 MiB
205 * instead of 4M before that.
206 * - indicates that we exchange additional settings in p_sizes
207 * drbd_send_sizes()/receive_sizes()
208 */
209 #define DRBD_FF_WSAME 4
210
211 /* supports REQ_OP_WRITE_ZEROES on the "wire" protocol.
212 *
213 * We used to map that to "discard" on the sending side, and if we cannot
214 * guarantee that discard zeroes data, the receiving side would map discard
215 * back to zero-out.
216 *
217 * With the introduction of REQ_OP_WRITE_ZEROES,
218 * we started to use that for both WRITE_ZEROES and DISCARDS,
219 * hoping that WRITE_ZEROES would "do what we want",
220 * UNMAP if possible, zero-out the rest.
221 *
222 * The example scenario is some LVM "thin" backend.
223 *
224 * While an un-allocated block on dm-thin reads as zeroes, on a dm-thin
225 * with "skip_block_zeroing=true", after a partial block write allocated
226 * that block, that same block may well map "undefined old garbage" from
227 * the backends on LBAs that have not yet been written to.
228 *
229 * If we cannot distinguish between zero-out and discard on the receiving
230 * side, to avoid "undefined old garbage" to pop up randomly at later times
231 * on supposedly zero-initialized blocks, we'd need to map all discards to
232 * zero-out on the receiving side. But that would potentially do a full
233 * alloc on thinly provisioned backends, even when the expectation was to
234 * unmap/trim/discard/de-allocate.
235 *
236 * We need to distinguish on the protocol level, whether we need to guarantee
237 * zeroes (and thus use zero-out, potentially doing the mentioned full-alloc),
238 * or if we want to put the emphasis on discard, and only do a "best effort
239 * zeroing" (by "discarding" blocks aligned to discard-granularity, and zeroing
240 * only potential unaligned head and tail clippings), to at least *try* to
241 * avoid "false positives" in an online-verify later, hoping that someone
242 * set skip_block_zeroing=false.
243 */
244 #define DRBD_FF_WZEROES 8
245
246
247 struct p_connection_features {
248 u32 protocol_min;
249 u32 feature_flags;
250 u32 protocol_max;
251
252 /* should be more than enough for future enhancements
253 * for now, feature_flags and the reserved array shall be zero.
254 */
255
256 u32 _pad;
257 u64 reserved[7];
258 } __packed;
259
260 struct p_barrier {
261 u32 barrier; /* barrier number _handle_ only */
262 u32 pad; /* to multiple of 8 Byte */
263 } __packed;
264
265 struct p_barrier_ack {
266 u32 barrier;
267 u32 set_size;
268 } __packed;
269
270 struct p_rs_param {
271 u32 resync_rate;
272
273 /* Since protocol version 88 and higher. */
274 char verify_alg[0];
275 } __packed;
276
277 struct p_rs_param_89 {
278 u32 resync_rate;
279 /* protocol version 89: */
280 char verify_alg[SHARED_SECRET_MAX];
281 char csums_alg[SHARED_SECRET_MAX];
282 } __packed;
283
284 struct p_rs_param_95 {
285 u32 resync_rate;
286 char verify_alg[SHARED_SECRET_MAX];
287 char csums_alg[SHARED_SECRET_MAX];
288 u32 c_plan_ahead;
289 u32 c_delay_target;
290 u32 c_fill_target;
291 u32 c_max_rate;
292 } __packed;
293
294 enum drbd_conn_flags {
295 CF_DISCARD_MY_DATA = 1,
296 CF_DRY_RUN = 2,
297 };
298
299 struct p_protocol {
300 u32 protocol;
301 u32 after_sb_0p;
302 u32 after_sb_1p;
303 u32 after_sb_2p;
304 u32 conn_flags;
305 u32 two_primaries;
306
307 /* Since protocol version 87 and higher. */
308 char integrity_alg[0];
309
310 } __packed;
311
312 struct p_uuids {
313 u64 uuid[UI_EXTENDED_SIZE];
314 } __packed;
315
316 struct p_rs_uuid {
317 u64 uuid;
318 } __packed;
319
320 /* optional queue_limits if (agreed_features & DRBD_FF_WSAME)
321 * see also struct queue_limits, as of late 2015 */
322 struct o_qlim {
323 /* we don't need it yet, but we may as well communicate it now */
324 u32 physical_block_size;
325
326 /* so the original in struct queue_limits is unsigned short,
327 * but I'd have to put in padding anyways. */
328 u32 logical_block_size;
329
330 /* One incoming bio becomes one DRBD request,
331 * which may be translated to several bio on the receiving side.
332 * We don't need to communicate chunk/boundary/segment ... limits.
333 */
334
335 /* various IO hints may be useful with "diskless client" setups */
336 u32 alignment_offset;
337 u32 io_min;
338 u32 io_opt;
339
340 /* We may need to communicate integrity stuff at some point,
341 * but let's not get ahead of ourselves. */
342
343 /* Backend discard capabilities.
344 * Receiving side uses "blkdev_issue_discard()", no need to communicate
345 * more specifics. If the backend cannot do discards, the DRBD peer
346 * may fall back to blkdev_issue_zeroout().
347 */
348 u8 discard_enabled;
349 u8 discard_zeroes_data;
350 u8 write_same_capable;
351 u8 _pad;
352 } __packed;
353
354 struct p_sizes {
355 u64 d_size; /* size of disk */
356 u64 u_size; /* user requested size */
357 u64 c_size; /* current exported size */
358 u32 max_bio_size; /* Maximal size of a BIO */
359 u16 queue_order_type; /* not yet implemented in DRBD*/
360 u16 dds_flags; /* use enum dds_flags here. */
361
362 /* optional queue_limits if (agreed_features & DRBD_FF_WSAME) */
363 struct o_qlim qlim[0];
364 } __packed;
365
366 struct p_state {
367 u32 state;
368 } __packed;
369
370 struct p_req_state {
371 u32 mask;
372 u32 val;
373 } __packed;
374
375 struct p_req_state_reply {
376 u32 retcode;
377 } __packed;
378
379 struct p_drbd06_param {
380 u64 size;
381 u32 state;
382 u32 blksize;
383 u32 protocol;
384 u32 version;
385 u32 gen_cnt[5];
386 u32 bit_map_gen[5];
387 } __packed;
388
389 struct p_block_desc {
390 u64 sector;
391 u32 blksize;
392 u32 pad; /* to multiple of 8 Byte */
393 } __packed;
394
395 /* Valid values for the encoding field.
396 * Bump proto version when changing this. */
397 enum drbd_bitmap_code {
398 /* RLE_VLI_Bytes = 0,
399 * and other bit variants had been defined during
400 * algorithm evaluation. */
401 RLE_VLI_Bits = 2,
402 };
403
404 struct p_compressed_bm {
405 /* (encoding & 0x0f): actual encoding, see enum drbd_bitmap_code
406 * (encoding & 0x80): polarity (set/unset) of first runlength
407 * ((encoding >> 4) & 0x07): pad_bits, number of trailing zero bits
408 * used to pad up to head.length bytes
409 */
410 u8 encoding;
411
412 u8 code[0];
413 } __packed;
414
415 struct p_delay_probe93 {
416 u32 seq_num; /* sequence number to match the two probe packets */
417 u32 offset; /* usecs the probe got sent after the reference time point */
418 } __packed;
419
420 /*
421 * Bitmap packets need to fit within a single page on the sender and receiver,
422 * so we are limited to 4 KiB (and not to PAGE_SIZE, which can be bigger).
423 */
424 #define DRBD_SOCKET_BUFFER_SIZE 4096
425
426 #endif /* __DRBD_PROTOCOL_H */