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