diff options
Diffstat (limited to 'drivers/block/drbd/drbd_protocol.h')
| -rw-r--r-- | drivers/block/drbd/drbd_protocol.h | 426 |
1 files changed, 426 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_protocol.h b/drivers/block/drbd/drbd_protocol.h new file mode 100644 index 000000000..dea59c92e --- /dev/null +++ b/drivers/block/drbd/drbd_protocol.h @@ -0,0 +1,426 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#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; + 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 */ |