/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * RDMA Network Block Driver
 *
 * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
 * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
 * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
 */
#ifndef RNBD_PROTO_H
#define RNBD_PROTO_H

#include <linux/types.h>
#include <linux/blkdev.h>
#include <linux/limits.h>
#include <linux/inet.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <rdma/ib.h>

#define RNBD_PROTO_VER_MAJOR 2
#define RNBD_PROTO_VER_MINOR 0

/* The default port number the RTRS server is listening on. */
#define RTRS_PORT 1234

/**
 * enum rnbd_msg_types - RNBD message types
 * @RNBD_MSG_SESS_INFO: initial session info from client to server
 * @RNBD_MSG_SESS_INFO_RSP:     initial session info from server to client
 * @RNBD_MSG_OPEN:              open (map) device request
 * @RNBD_MSG_OPEN_RSP:          response to an @RNBD_MSG_OPEN
 * @RNBD_MSG_IO:                block IO request operation
 * @RNBD_MSG_CLOSE:             close (unmap) device request
 */
enum rnbd_msg_type {
        RNBD_MSG_SESS_INFO,
        RNBD_MSG_SESS_INFO_RSP,
        RNBD_MSG_OPEN,
        RNBD_MSG_OPEN_RSP,
        RNBD_MSG_IO,
        RNBD_MSG_CLOSE,
};

/**
 * struct rnbd_msg_hdr - header of RNBD messages
 * @type:       Message type, valid values see: enum rnbd_msg_types
 */
struct rnbd_msg_hdr {
        __le16          type;
        __le16          __padding;
};

/**
 * We allow to map RO many times and RW only once. We allow to map yet another
 * time RW, if MIGRATION is provided (second RW export can be required for
 * example for VM migration)
 */
enum rnbd_access_mode {
        RNBD_ACCESS_RO,
        RNBD_ACCESS_RW,
        RNBD_ACCESS_MIGRATION,
};

/**
 * struct rnbd_msg_sess_info - initial session info from client to server
 * @hdr:                message header
 * @ver:                RNBD protocol version
 */
struct rnbd_msg_sess_info {
        struct rnbd_msg_hdr hdr;
        u8              ver;
        u8              reserved[31];
};

/**
 * struct rnbd_msg_sess_info_rsp - initial session info from server to client
 * @hdr:                message header
 * @ver:                RNBD protocol version
 */
struct rnbd_msg_sess_info_rsp {
        struct rnbd_msg_hdr hdr;
        u8              ver;
        u8              reserved[31];
};

/**
 * struct rnbd_msg_open - request to open a remote device.
 * @hdr:                message header
 * @access_mode:        the mode to open remote device, valid values see:
 *                      enum rnbd_access_mode
 * @device_name:        device path on remote side
 */
struct rnbd_msg_open {
        struct rnbd_msg_hdr hdr;
        u8              access_mode;
        u8              resv1;
        s8              dev_name[NAME_MAX];
        u8              reserved[3];
};

/**
 * struct rnbd_msg_close - request to close a remote device.
 * @hdr:        message header
 * @device_id:  device_id on server side to identify the device
 */
struct rnbd_msg_close {
        struct rnbd_msg_hdr hdr;
        __le32          device_id;
};

enum rnbd_cache_policy {
        RNBD_FUA = 1 << 0,
        RNBD_WRITEBACK = 1 << 1,
};

/**
 * struct rnbd_msg_open_rsp - response message to RNBD_MSG_OPEN
 * @hdr:                message header
 * @device_id:          device_id on server side to identify the device
 * @nsectors:           number of sectors in the usual 512b unit
 * @max_hw_sectors:     max hardware sectors in the usual 512b unit
 * @max_write_same_sectors: max sectors for WRITE SAME in the 512b unit
 * @max_discard_sectors: max. sectors that can be discarded at once in 512b
 * unit.
 * @discard_granularity: size of the internal discard allocation unit in bytes
 * @discard_alignment: offset from internal allocation assignment in bytes
 * @physical_block_size: physical block size device supports in bytes
 * @logical_block_size: logical block size device supports in bytes
 * @max_segments:       max segments hardware support in one transfer
 * @secure_discard:     supports secure discard
 * @rotation:           is a rotational disc?
 * @cache_policy:       support write-back caching or FUA?
 */
struct rnbd_msg_open_rsp {
        struct rnbd_msg_hdr     hdr;
        __le32                  device_id;
        __le64                  nsectors;
        __le32                  max_hw_sectors;
        __le32                  max_write_same_sectors;
        __le32                  max_discard_sectors;
        __le32                  discard_granularity;
        __le32                  discard_alignment;
        __le16                  physical_block_size;
        __le16                  logical_block_size;
        __le16                  max_segments;
        __le16                  secure_discard;
        u8                      rotational;
        u8                      cache_policy;
        u8                      reserved[10];
};

/**
 * struct rnbd_msg_io - message for I/O read/write
 * @hdr:        message header
 * @device_id:  device_id on server side to find the right device
 * @sector:     bi_sector attribute from struct bio
 * @rw:         valid values are defined in enum rnbd_io_flags
 * @bi_size:    number of bytes for I/O read/write
 * @prio:       priority
 */
struct rnbd_msg_io {
        struct rnbd_msg_hdr hdr;
        __le32          device_id;
        __le64          sector;
        __le32          rw;
        __le32          bi_size;
        __le16          prio;
};

#define RNBD_OP_BITS  8
#define RNBD_OP_MASK  ((1 << RNBD_OP_BITS) - 1)

/**
 * enum rnbd_io_flags - RNBD request types from rq_flag_bits
 * @RNBD_OP_READ:            read sectors from the device
 * @RNBD_OP_WRITE:           write sectors to the device
 * @RNBD_OP_FLUSH:           flush the volatile write cache
 * @RNBD_OP_DISCARD:        discard sectors
 * @RNBD_OP_SECURE_ERASE:   securely erase sectors
 * @RNBD_OP_WRITE_SAME:     write the same sectors many times

 * @RNBD_F_SYNC:             request is sync (sync write or read)
 * @RNBD_F_FUA:             forced unit access
 */
enum rnbd_io_flags {

        /* Operations */

        RNBD_OP_READ            = 0,
        RNBD_OP_WRITE           = 1,
        RNBD_OP_FLUSH           = 2,
        RNBD_OP_DISCARD = 3,
        RNBD_OP_SECURE_ERASE    = 4,
        RNBD_OP_WRITE_SAME      = 5,

        RNBD_OP_LAST,

        /* Flags */

        RNBD_F_SYNC  = 1<<(RNBD_OP_BITS + 0),
        RNBD_F_FUA   = 1<<(RNBD_OP_BITS + 1),

        RNBD_F_ALL   = (RNBD_F_SYNC | RNBD_F_FUA)

};

static inline u32 rnbd_op(u32 flags)
{
        return flags & RNBD_OP_MASK;
}

static inline u32 rnbd_flags(u32 flags)
{
        return flags & ~RNBD_OP_MASK;
}

static inline bool rnbd_flags_supported(u32 flags)
{
        u32 op;

        op = rnbd_op(flags);
        flags = rnbd_flags(flags);

        if (op >= RNBD_OP_LAST)
                return false;
        if (flags & ~RNBD_F_ALL)
                return false;

        return true;
}

static inline u32 rnbd_to_bio_flags(u32 rnbd_opf)
{
        u32 bio_opf;

        switch (rnbd_op(rnbd_opf)) {
        case RNBD_OP_READ:
                bio_opf = REQ_OP_READ;
                break;
        case RNBD_OP_WRITE:
                bio_opf = REQ_OP_WRITE;
                break;
        case RNBD_OP_FLUSH:
                bio_opf = REQ_OP_FLUSH | REQ_PREFLUSH;
                break;
        case RNBD_OP_DISCARD:
                bio_opf = REQ_OP_DISCARD;
                break;
        case RNBD_OP_SECURE_ERASE:
                bio_opf = REQ_OP_SECURE_ERASE;
                break;
        case RNBD_OP_WRITE_SAME:
                bio_opf = REQ_OP_WRITE_SAME;
                break;
        default:
                WARN(1, "Unknown RNBD type: %d (flags %d)\n",
                     rnbd_op(rnbd_opf), rnbd_opf);
                bio_opf = 0;
        }

        if (rnbd_opf & RNBD_F_SYNC)
                bio_opf |= REQ_SYNC;

        if (rnbd_opf & RNBD_F_FUA)
                bio_opf |= REQ_FUA;

        return bio_opf;
}

static inline u32 rq_to_rnbd_flags(struct request *rq)
{
        u32 rnbd_opf;

        switch (req_op(rq)) {
        case REQ_OP_READ:
                rnbd_opf = RNBD_OP_READ;
                break;
        case REQ_OP_WRITE:
                rnbd_opf = RNBD_OP_WRITE;
                break;
        case REQ_OP_DISCARD:
                rnbd_opf = RNBD_OP_DISCARD;
                break;
        case REQ_OP_SECURE_ERASE:
                rnbd_opf = RNBD_OP_SECURE_ERASE;
                break;
        case REQ_OP_WRITE_SAME:
                rnbd_opf = RNBD_OP_WRITE_SAME;
                break;
        case REQ_OP_FLUSH:
                rnbd_opf = RNBD_OP_FLUSH;
                break;
        default:
                WARN(1, "Unknown request type %d (flags %llu)\n",
                     req_op(rq), (unsigned long long)rq->cmd_flags);
                rnbd_opf = 0;
        }

        if (op_is_sync(rq->cmd_flags))
                rnbd_opf |= RNBD_F_SYNC;

        if (op_is_flush(rq->cmd_flags))
                rnbd_opf |= RNBD_F_FUA;

        return rnbd_opf;
}

const char *rnbd_access_mode_str(enum rnbd_access_mode mode);

#endif /* RNBD_PROTO_H */