drivers/block/drbd/drbd_protocol.h

   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_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  */
  98 struct 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 */
 105 struct p_header95 {
 106         u16       magic;        /* use DRBD_MAGIC_BIG here */
 107         u16       command;
 108         u32       length;
 109 } __packed;
 110
 111 struct 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
 134 struct 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
 141 struct p_trim {
 142         struct p_data p_data;
 143         u32         size;       /* == bio->bi_size */
 144 } __packed;
 145
 146 struct 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  */
 159 struct p_block_ack {
 160         u64         sector;
 161         u64         block_id;
 162         u32         blksize;
 163         u32         seq_num;
 164 } __packed;
 165
 166 struct 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
 200 struct 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
 213 struct p_barrier {
 214         u32 barrier;    /* barrier number _handle_ only */
 215         u32 pad;        /* to multiple of 8 Byte */
 216 } __packed;
 217
 218 struct p_barrier_ack {
 219         u32 barrier;
 220         u32 set_size;
 221 } __packed;
 222
 223 struct p_rs_param {
 224         u32 resync_rate;
 225
 226               /* Since protocol version 88 and higher. */
 227         char verify_alg[0];
 228 } __packed;
 229
 230 struct 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
 237 struct 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
 247 enum drbd_conn_flags {
 248         CF_DISCARD_MY_DATA = 1,
 249         CF_DRY_RUN = 2,
 250 };
 251
 252 struct 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
 265 struct p_uuids {
 266         u64 uuid[UI_EXTENDED_SIZE];
 267 } __packed;
 268
 269 struct 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 */
 275 struct 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
 307 struct 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
 319 struct p_state {
 320         u32         state;
 321 } __packed;
 322
 323 struct p_req_state {
 324         u32         mask;
 325         u32         val;
 326 } __packed;
 327
 328 struct p_req_state_reply {
 329         u32         retcode;
 330 } __packed;
 331
 332 struct 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
 342 struct 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. */
 350 enum 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
 357 struct 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
 368 struct 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 */