1/* SPDX-License-Identifier: GPL-2.0-only */ 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_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 */ 103struct 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 */ 110struct p_header95 { 111 u16 magic; /* use DRBD_MAGIC_BIG here */ 112 u16 command; 113 u32 length; 114} __packed; 115 116struct 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 145struct 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 152struct p_trim { 153 struct p_data p_data; 154 u32 size; /* == bio->bi_size */ 155} __packed; 156 157struct 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 */ 170struct p_block_ack { 171 u64 sector; 172 u64 block_id; 173 u32 blksize; 174 u32 seq_num; 175} __packed; 176 177struct 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 247struct 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 260struct p_barrier { 261 u32 barrier; /* barrier number _handle_ only */ 262 u32 pad; /* to multiple of 8 Byte */ 263} __packed; 264 265struct p_barrier_ack { 266 u32 barrier; 267 u32 set_size; 268} __packed; 269 270struct p_rs_param { 271 u32 resync_rate; 272 273 /* Since protocol version 88 and higher. */ 274 char verify_alg[]; 275} __packed; 276 277struct 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 284struct p_rs_param_95 { 285 u32 resync_rate; 286 struct_group(algs, 287 char verify_alg[SHARED_SECRET_MAX]; 288 char csums_alg[SHARED_SECRET_MAX]; 289 ); 290 u32 c_plan_ahead; 291 u32 c_delay_target; 292 u32 c_fill_target; 293 u32 c_max_rate; 294} __packed; 295 296enum drbd_conn_flags { 297 CF_DISCARD_MY_DATA = 1, 298 CF_DRY_RUN = 2, 299}; 300 301struct p_protocol { 302 u32 protocol; 303 u32 after_sb_0p; 304 u32 after_sb_1p; 305 u32 after_sb_2p; 306 u32 conn_flags; 307 u32 two_primaries; 308 309 /* Since protocol version 87 and higher. */ 310 char integrity_alg[]; 311 312} __packed; 313 314struct p_uuids { 315 u64 uuid[UI_EXTENDED_SIZE]; 316} __packed; 317 318struct p_rs_uuid { 319 u64 uuid; 320} __packed; 321 322/* optional queue_limits if (agreed_features & DRBD_FF_WSAME) 323 * see also struct queue_limits, as of late 2015 */ 324struct o_qlim { 325 /* we don't need it yet, but we may as well communicate it now */ 326 u32 physical_block_size; 327 328 /* so the original in struct queue_limits is unsigned short, 329 * but I'd have to put in padding anyways. */ 330 u32 logical_block_size; 331 332 /* One incoming bio becomes one DRBD request, 333 * which may be translated to several bio on the receiving side. 334 * We don't need to communicate chunk/boundary/segment ... limits. 335 */ 336 337 /* various IO hints may be useful with "diskless client" setups */ 338 u32 alignment_offset; 339 u32 io_min; 340 u32 io_opt; 341 342 /* We may need to communicate integrity stuff at some point, 343 * but let's not get ahead of ourselves. */ 344 345 /* Backend discard capabilities. 346 * Receiving side uses "blkdev_issue_discard()", no need to communicate 347 * more specifics. If the backend cannot do discards, the DRBD peer 348 * may fall back to blkdev_issue_zeroout(). 349 */ 350 u8 discard_enabled; 351 u8 discard_zeroes_data; 352 u8 write_same_capable; 353 u8 _pad; 354} __packed; 355 356struct p_sizes { 357 u64 d_size; /* size of disk */ 358 u64 u_size; /* user requested size */ 359 u64 c_size; /* current exported size */ 360 u32 max_bio_size; /* Maximal size of a BIO */ 361 u16 queue_order_type; /* not yet implemented in DRBD*/ 362 u16 dds_flags; /* use enum dds_flags here. */ 363 364 /* optional queue_limits if (agreed_features & DRBD_FF_WSAME) */ 365 struct o_qlim qlim[]; 366} __packed; 367 368struct p_state { 369 u32 state; 370} __packed; 371 372struct p_req_state { 373 u32 mask; 374 u32 val; 375} __packed; 376 377struct p_req_state_reply { 378 u32 retcode; 379} __packed; 380 381struct p_drbd06_param { 382 u64 size; 383 u32 state; 384 u32 blksize; 385 u32 protocol; 386 u32 version; 387 u32 gen_cnt[5]; 388 u32 bit_map_gen[5]; 389} __packed; 390 391struct p_block_desc { 392 u64 sector; 393 u32 blksize; 394 u32 pad; /* to multiple of 8 Byte */ 395} __packed; 396 397/* Valid values for the encoding field. 398 * Bump proto version when changing this. */ 399enum drbd_bitmap_code { 400 /* RLE_VLI_Bytes = 0, 401 * and other bit variants had been defined during 402 * algorithm evaluation. */ 403 RLE_VLI_Bits = 2, 404}; 405 406struct p_compressed_bm { 407 /* (encoding & 0x0f): actual encoding, see enum drbd_bitmap_code 408 * (encoding & 0x80): polarity (set/unset) of first runlength 409 * ((encoding >> 4) & 0x07): pad_bits, number of trailing zero bits 410 * used to pad up to head.length bytes 411 */ 412 u8 encoding; 413 414 u8 code[]; 415} __packed; 416 417struct p_delay_probe93 { 418 u32 seq_num; /* sequence number to match the two probe packets */ 419 u32 offset; /* usecs the probe got sent after the reference time point */ 420} __packed; 421 422/* 423 * Bitmap packets need to fit within a single page on the sender and receiver, 424 * so we are limited to 4 KiB (and not to PAGE_SIZE, which can be bigger). 425 */ 426#define DRBD_SOCKET_BUFFER_SIZE 4096 427 428#endif /* __DRBD_PROTOCOL_H */ 429