/* 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 */