drivers/block/drbd/drbd_protocol.h

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