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426 lines
13 KiB
426 lines
13 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __DRBD_PROTOCOL_H |
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#define __DRBD_PROTOCOL_H |
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enum drbd_packet { |
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/* receiver (data socket) */ |
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P_DATA = 0x00, |
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P_DATA_REPLY = 0x01, /* Response to P_DATA_REQUEST */ |
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P_RS_DATA_REPLY = 0x02, /* Response to P_RS_DATA_REQUEST */ |
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P_BARRIER = 0x03, |
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P_BITMAP = 0x04, |
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P_BECOME_SYNC_TARGET = 0x05, |
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P_BECOME_SYNC_SOURCE = 0x06, |
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P_UNPLUG_REMOTE = 0x07, /* Used at various times to hint the peer */ |
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P_DATA_REQUEST = 0x08, /* Used to ask for a data block */ |
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P_RS_DATA_REQUEST = 0x09, /* Used to ask for a data block for resync */ |
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P_SYNC_PARAM = 0x0a, |
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P_PROTOCOL = 0x0b, |
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P_UUIDS = 0x0c, |
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P_SIZES = 0x0d, |
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P_STATE = 0x0e, |
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P_SYNC_UUID = 0x0f, |
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P_AUTH_CHALLENGE = 0x10, |
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P_AUTH_RESPONSE = 0x11, |
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P_STATE_CHG_REQ = 0x12, |
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/* (meta socket) */ |
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P_PING = 0x13, |
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P_PING_ACK = 0x14, |
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P_RECV_ACK = 0x15, /* Used in protocol B */ |
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P_WRITE_ACK = 0x16, /* Used in protocol C */ |
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P_RS_WRITE_ACK = 0x17, /* Is a P_WRITE_ACK, additionally call set_in_sync(). */ |
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P_SUPERSEDED = 0x18, /* Used in proto C, two-primaries conflict detection */ |
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P_NEG_ACK = 0x19, /* Sent if local disk is unusable */ |
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P_NEG_DREPLY = 0x1a, /* Local disk is broken... */ |
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P_NEG_RS_DREPLY = 0x1b, /* Local disk is broken... */ |
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P_BARRIER_ACK = 0x1c, |
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P_STATE_CHG_REPLY = 0x1d, |
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/* "new" commands, no longer fitting into the ordering scheme above */ |
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P_OV_REQUEST = 0x1e, /* data socket */ |
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P_OV_REPLY = 0x1f, |
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P_OV_RESULT = 0x20, /* meta socket */ |
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P_CSUM_RS_REQUEST = 0x21, /* data socket */ |
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P_RS_IS_IN_SYNC = 0x22, /* meta socket */ |
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P_SYNC_PARAM89 = 0x23, /* data socket, protocol version 89 replacement for P_SYNC_PARAM */ |
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P_COMPRESSED_BITMAP = 0x24, /* compressed or otherwise encoded bitmap transfer */ |
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/* P_CKPT_FENCE_REQ = 0x25, * currently reserved for protocol D */ |
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/* P_CKPT_DISABLE_REQ = 0x26, * currently reserved for protocol D */ |
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P_DELAY_PROBE = 0x27, /* is used on BOTH sockets */ |
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P_OUT_OF_SYNC = 0x28, /* Mark as out of sync (Outrunning), data socket */ |
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P_RS_CANCEL = 0x29, /* meta: Used to cancel RS_DATA_REQUEST packet by SyncSource */ |
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P_CONN_ST_CHG_REQ = 0x2a, /* data sock: Connection wide state request */ |
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P_CONN_ST_CHG_REPLY = 0x2b, /* meta sock: Connection side state req reply */ |
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P_RETRY_WRITE = 0x2c, /* Protocol C: retry conflicting write request */ |
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P_PROTOCOL_UPDATE = 0x2d, /* data sock: is used in established connections */ |
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/* 0x2e to 0x30 reserved, used in drbd 9 */ |
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/* REQ_OP_DISCARD. We used "discard" in different contexts before, |
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* which is why I chose TRIM here, to disambiguate. */ |
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P_TRIM = 0x31, |
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/* Only use these two if both support FF_THIN_RESYNC */ |
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P_RS_THIN_REQ = 0x32, /* Request a block for resync or reply P_RS_DEALLOCATED */ |
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P_RS_DEALLOCATED = 0x33, /* Contains only zeros on sync source node */ |
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/* REQ_WRITE_SAME. |
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* On a receiving side without REQ_WRITE_SAME, |
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* we may fall back to an opencoded loop instead. */ |
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P_WSAME = 0x34, |
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/* 0x35 already claimed in DRBD 9 */ |
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P_ZEROES = 0x36, /* data sock: zero-out, WRITE_ZEROES */ |
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/* 0x40 .. 0x48 already claimed in DRBD 9 */ |
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P_MAY_IGNORE = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */ |
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P_MAX_OPT_CMD = 0x101, |
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/* special command ids for handshake */ |
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P_INITIAL_META = 0xfff1, /* First Packet on the MetaSock */ |
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P_INITIAL_DATA = 0xfff2, /* First Packet on the Socket */ |
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P_CONNECTION_FEATURES = 0xfffe /* FIXED for the next century! */ |
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}; |
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#ifndef __packed |
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#define __packed __attribute__((packed)) |
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#endif |
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/* This is the layout for a packet on the wire. |
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* The byteorder is the network byte order. |
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* (except block_id and barrier fields. |
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* these are pointers to local structs |
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* and have no relevance for the partner, |
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* which just echoes them as received.) |
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* |
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* NOTE that the payload starts at a long aligned offset, |
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* regardless of 32 or 64 bit arch! |
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*/ |
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struct p_header80 { |
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u32 magic; |
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u16 command; |
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u16 length; /* bytes of data after this header */ |
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} __packed; |
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/* Header for big packets, Used for data packets exceeding 64kB */ |
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struct p_header95 { |
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u16 magic; /* use DRBD_MAGIC_BIG here */ |
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u16 command; |
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u32 length; |
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} __packed; |
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struct p_header100 { |
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u32 magic; |
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u16 volume; |
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u16 command; |
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u32 length; |
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u32 pad; |
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} __packed; |
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/* These defines must not be changed without changing the protocol version. |
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* New defines may only be introduced together with protocol version bump or |
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* new protocol feature flags. |
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*/ |
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#define DP_HARDBARRIER 1 /* no longer used */ |
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#define DP_RW_SYNC 2 /* equals REQ_SYNC */ |
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#define DP_MAY_SET_IN_SYNC 4 |
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#define DP_UNPLUG 8 /* not used anymore */ |
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#define DP_FUA 16 /* equals REQ_FUA */ |
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#define DP_FLUSH 32 /* equals REQ_PREFLUSH */ |
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#define DP_DISCARD 64 /* equals REQ_OP_DISCARD */ |
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#define DP_SEND_RECEIVE_ACK 128 /* This is a proto B write request */ |
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#define DP_SEND_WRITE_ACK 256 /* This is a proto C write request */ |
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#define DP_WSAME 512 /* equiv. REQ_WRITE_SAME */ |
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#define DP_ZEROES 1024 /* equiv. REQ_OP_WRITE_ZEROES */ |
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/* possible combinations: |
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* REQ_OP_WRITE_ZEROES: DP_DISCARD | DP_ZEROES |
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* REQ_OP_WRITE_ZEROES + REQ_NOUNMAP: DP_ZEROES |
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*/ |
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struct p_data { |
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u64 sector; /* 64 bits sector number */ |
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u64 block_id; /* to identify the request in protocol B&C */ |
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u32 seq_num; |
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u32 dp_flags; |
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} __packed; |
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struct p_trim { |
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struct p_data p_data; |
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u32 size; /* == bio->bi_size */ |
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} __packed; |
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struct p_wsame { |
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struct p_data p_data; |
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u32 size; /* == bio->bi_size */ |
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} __packed; |
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/* |
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* commands which share a struct: |
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* p_block_ack: |
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* P_RECV_ACK (proto B), P_WRITE_ACK (proto C), |
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* P_SUPERSEDED (proto C, two-primaries conflict detection) |
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* p_block_req: |
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* P_DATA_REQUEST, P_RS_DATA_REQUEST |
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*/ |
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struct p_block_ack { |
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u64 sector; |
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u64 block_id; |
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u32 blksize; |
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u32 seq_num; |
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} __packed; |
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struct p_block_req { |
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u64 sector; |
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u64 block_id; |
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u32 blksize; |
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u32 pad; /* to multiple of 8 Byte */ |
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} __packed; |
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/* |
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* commands with their own struct for additional fields: |
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* P_CONNECTION_FEATURES |
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* P_BARRIER |
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* P_BARRIER_ACK |
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* P_SYNC_PARAM |
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* ReportParams |
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*/ |
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/* supports TRIM/DISCARD on the "wire" protocol */ |
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#define DRBD_FF_TRIM 1 |
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/* Detect all-zeros during resync, and rather TRIM/UNMAP/DISCARD those blocks |
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* instead of fully allocate a supposedly thin volume on initial resync */ |
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#define DRBD_FF_THIN_RESYNC 2 |
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/* supports REQ_WRITE_SAME on the "wire" protocol. |
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* Note: this flag is overloaded, |
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* its presence also |
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* - indicates support for 128 MiB "batch bios", |
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* max discard size of 128 MiB |
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* instead of 4M before that. |
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* - indicates that we exchange additional settings in p_sizes |
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* drbd_send_sizes()/receive_sizes() |
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*/ |
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#define DRBD_FF_WSAME 4 |
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/* supports REQ_OP_WRITE_ZEROES on the "wire" protocol. |
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* |
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* We used to map that to "discard" on the sending side, and if we cannot |
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* guarantee that discard zeroes data, the receiving side would map discard |
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* back to zero-out. |
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* |
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* With the introduction of REQ_OP_WRITE_ZEROES, |
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* we started to use that for both WRITE_ZEROES and DISCARDS, |
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* hoping that WRITE_ZEROES would "do what we want", |
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* UNMAP if possible, zero-out the rest. |
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* |
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* The example scenario is some LVM "thin" backend. |
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* |
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* While an un-allocated block on dm-thin reads as zeroes, on a dm-thin |
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* with "skip_block_zeroing=true", after a partial block write allocated |
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* that block, that same block may well map "undefined old garbage" from |
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* the backends on LBAs that have not yet been written to. |
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* |
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* If we cannot distinguish between zero-out and discard on the receiving |
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* side, to avoid "undefined old garbage" to pop up randomly at later times |
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* on supposedly zero-initialized blocks, we'd need to map all discards to |
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* zero-out on the receiving side. But that would potentially do a full |
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* alloc on thinly provisioned backends, even when the expectation was to |
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* unmap/trim/discard/de-allocate. |
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* |
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* We need to distinguish on the protocol level, whether we need to guarantee |
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* zeroes (and thus use zero-out, potentially doing the mentioned full-alloc), |
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* or if we want to put the emphasis on discard, and only do a "best effort |
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* zeroing" (by "discarding" blocks aligned to discard-granularity, and zeroing |
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* only potential unaligned head and tail clippings), to at least *try* to |
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* avoid "false positives" in an online-verify later, hoping that someone |
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* set skip_block_zeroing=false. |
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*/ |
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#define DRBD_FF_WZEROES 8 |
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struct p_connection_features { |
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u32 protocol_min; |
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u32 feature_flags; |
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u32 protocol_max; |
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/* should be more than enough for future enhancements |
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* for now, feature_flags and the reserved array shall be zero. |
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*/ |
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u32 _pad; |
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u64 reserved[7]; |
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} __packed; |
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struct p_barrier { |
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u32 barrier; /* barrier number _handle_ only */ |
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u32 pad; /* to multiple of 8 Byte */ |
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} __packed; |
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struct p_barrier_ack { |
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u32 barrier; |
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u32 set_size; |
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} __packed; |
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struct p_rs_param { |
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u32 resync_rate; |
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/* Since protocol version 88 and higher. */ |
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char verify_alg[]; |
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} __packed; |
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struct p_rs_param_89 { |
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u32 resync_rate; |
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/* protocol version 89: */ |
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char verify_alg[SHARED_SECRET_MAX]; |
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char csums_alg[SHARED_SECRET_MAX]; |
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} __packed; |
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struct p_rs_param_95 { |
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u32 resync_rate; |
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char verify_alg[SHARED_SECRET_MAX]; |
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char csums_alg[SHARED_SECRET_MAX]; |
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u32 c_plan_ahead; |
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u32 c_delay_target; |
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u32 c_fill_target; |
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u32 c_max_rate; |
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} __packed; |
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enum drbd_conn_flags { |
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CF_DISCARD_MY_DATA = 1, |
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CF_DRY_RUN = 2, |
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}; |
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struct p_protocol { |
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u32 protocol; |
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u32 after_sb_0p; |
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u32 after_sb_1p; |
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u32 after_sb_2p; |
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u32 conn_flags; |
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u32 two_primaries; |
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/* Since protocol version 87 and higher. */ |
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char integrity_alg[]; |
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} __packed; |
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struct p_uuids { |
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u64 uuid[UI_EXTENDED_SIZE]; |
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} __packed; |
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struct p_rs_uuid { |
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u64 uuid; |
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} __packed; |
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/* optional queue_limits if (agreed_features & DRBD_FF_WSAME) |
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* see also struct queue_limits, as of late 2015 */ |
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struct o_qlim { |
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/* we don't need it yet, but we may as well communicate it now */ |
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u32 physical_block_size; |
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/* so the original in struct queue_limits is unsigned short, |
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* but I'd have to put in padding anyways. */ |
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u32 logical_block_size; |
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/* One incoming bio becomes one DRBD request, |
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* which may be translated to several bio on the receiving side. |
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* We don't need to communicate chunk/boundary/segment ... limits. |
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*/ |
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/* various IO hints may be useful with "diskless client" setups */ |
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u32 alignment_offset; |
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u32 io_min; |
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u32 io_opt; |
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/* We may need to communicate integrity stuff at some point, |
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* but let's not get ahead of ourselves. */ |
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/* Backend discard capabilities. |
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* Receiving side uses "blkdev_issue_discard()", no need to communicate |
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* more specifics. If the backend cannot do discards, the DRBD peer |
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* may fall back to blkdev_issue_zeroout(). |
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*/ |
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u8 discard_enabled; |
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u8 discard_zeroes_data; |
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u8 write_same_capable; |
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u8 _pad; |
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} __packed; |
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struct p_sizes { |
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u64 d_size; /* size of disk */ |
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u64 u_size; /* user requested size */ |
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u64 c_size; /* current exported size */ |
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u32 max_bio_size; /* Maximal size of a BIO */ |
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u16 queue_order_type; /* not yet implemented in DRBD*/ |
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u16 dds_flags; /* use enum dds_flags here. */ |
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/* optional queue_limits if (agreed_features & DRBD_FF_WSAME) */ |
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struct o_qlim qlim[]; |
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} __packed; |
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struct p_state { |
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u32 state; |
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} __packed; |
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struct p_req_state { |
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u32 mask; |
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u32 val; |
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} __packed; |
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struct p_req_state_reply { |
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u32 retcode; |
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} __packed; |
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struct p_drbd06_param { |
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u64 size; |
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u32 state; |
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u32 blksize; |
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u32 protocol; |
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u32 version; |
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u32 gen_cnt[5]; |
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u32 bit_map_gen[5]; |
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} __packed; |
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struct p_block_desc { |
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u64 sector; |
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u32 blksize; |
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u32 pad; /* to multiple of 8 Byte */ |
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} __packed; |
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/* Valid values for the encoding field. |
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* Bump proto version when changing this. */ |
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enum drbd_bitmap_code { |
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/* RLE_VLI_Bytes = 0, |
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* and other bit variants had been defined during |
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* algorithm evaluation. */ |
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RLE_VLI_Bits = 2, |
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}; |
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struct p_compressed_bm { |
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/* (encoding & 0x0f): actual encoding, see enum drbd_bitmap_code |
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* (encoding & 0x80): polarity (set/unset) of first runlength |
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* ((encoding >> 4) & 0x07): pad_bits, number of trailing zero bits |
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* used to pad up to head.length bytes |
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*/ |
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u8 encoding; |
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u8 code[]; |
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} __packed; |
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struct p_delay_probe93 { |
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u32 seq_num; /* sequence number to match the two probe packets */ |
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u32 offset; /* usecs the probe got sent after the reference time point */ |
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} __packed; |
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/* |
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* Bitmap packets need to fit within a single page on the sender and receiver, |
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* so we are limited to 4 KiB (and not to PAGE_SIZE, which can be bigger). |
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*/ |
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#define DRBD_SOCKET_BUFFER_SIZE 4096 |
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#endif /* __DRBD_PROTOCOL_H */
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