429 lines
13 KiB
C
429 lines
13 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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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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struct_group(algs,
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char verify_alg[SHARED_SECRET_MAX];
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char csums_alg[SHARED_SECRET_MAX];
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);
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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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