/*
 * Discovery service for the NVMe over Fabrics target.
 * Copyright (C) 2016 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/slab.h>
#include <generated/utsrelease.h>
#include "nvmet.h"

struct nvmet_subsys *nvmet_disc_subsys;

u64 nvmet_genctr;

void nvmet_referral_enable(struct nvmet_port *parent, struct nvmet_port *port)
{
        down_write(&nvmet_config_sem);
        if (list_empty(&port->entry)) {
                list_add_tail(&port->entry, &parent->referrals);
                port->enabled = true;
                nvmet_genctr++;
        }
        up_write(&nvmet_config_sem);
}

void nvmet_referral_disable(struct nvmet_port *port)
{
        down_write(&nvmet_config_sem);
        if (!list_empty(&port->entry)) {
                port->enabled = false;
                list_del_init(&port->entry);
                nvmet_genctr++;
        }
        up_write(&nvmet_config_sem);
}

static void nvmet_format_discovery_entry(struct nvmf_disc_rsp_page_hdr *hdr,
                struct nvmet_port *port, char *subsys_nqn, u8 type, u32 numrec)
{
        struct nvmf_disc_rsp_page_entry *e = &hdr->entries[numrec];

        e->trtype = port->disc_addr.trtype;
        e->adrfam = port->disc_addr.adrfam;
        e->treq = port->disc_addr.treq;
        e->portid = port->disc_addr.portid;
        /* we support only dynamic controllers */
        e->cntlid = cpu_to_le16(NVME_CNTLID_DYNAMIC);
        e->asqsz = cpu_to_le16(NVMF_AQ_DEPTH);
        e->subtype = type;
        memcpy(e->trsvcid, port->disc_addr.trsvcid, NVMF_TRSVCID_SIZE);
        memcpy(e->traddr, port->disc_addr.traddr, NVMF_TRADDR_SIZE);
        memcpy(e->tsas.common, port->disc_addr.tsas.common, NVMF_TSAS_SIZE);
        memcpy(e->subnqn, subsys_nqn, NVMF_NQN_SIZE);
}

static void nvmet_execute_get_disc_log_page(struct nvmet_req *req)
{
        const int entry_size = sizeof(struct nvmf_disc_rsp_page_entry);
        struct nvmet_ctrl *ctrl = req->sq->ctrl;
        struct nvmf_disc_rsp_page_hdr *hdr;
        size_t data_len = nvmet_get_log_page_len(req->cmd);
        size_t alloc_len = max(data_len, sizeof(*hdr));
        int residual_len = data_len - sizeof(*hdr);
        struct nvmet_subsys_link *p;
        struct nvmet_port *r;
        u32 numrec = 0;
        u16 status = 0;

        /*
         * Make sure we're passing at least a buffer of response header size.
         * If host provided data len is less than the header size, only the
         * number of bytes requested by host will be sent to host.
         */
        hdr = kzalloc(alloc_len, GFP_KERNEL);
        if (!hdr) {
                status = NVME_SC_INTERNAL;
                goto out;
        }

        down_read(&nvmet_config_sem);
        list_for_each_entry(p, &req->port->subsystems, entry) {
                if (!nvmet_host_allowed(req, p->subsys, ctrl->hostnqn))
                        continue;
                if (residual_len >= entry_size) {
                        nvmet_format_discovery_entry(hdr, req->port,
                                        p->subsys->subsysnqn,
                                        NVME_NQN_NVME, numrec);
                        residual_len -= entry_size;
                }
                numrec++;
        }

        list_for_each_entry(r, &req->port->referrals, entry) {
                if (residual_len >= entry_size) {
                        nvmet_format_discovery_entry(hdr, r,
                                        NVME_DISC_SUBSYS_NAME,
                                        NVME_NQN_DISC, numrec);
                        residual_len -= entry_size;
                }
                numrec++;
        }

        hdr->genctr = cpu_to_le64(nvmet_genctr);
        hdr->numrec = cpu_to_le64(numrec);
        hdr->recfmt = cpu_to_le16(0);

        up_read(&nvmet_config_sem);

        status = nvmet_copy_to_sgl(req, 0, hdr, data_len);
        kfree(hdr);
out:
        nvmet_req_complete(req, status);
}

static void nvmet_execute_identify_disc_ctrl(struct nvmet_req *req)
{
        struct nvmet_ctrl *ctrl = req->sq->ctrl;
        struct nvme_id_ctrl *id;
        u16 status = 0;

        id = kzalloc(sizeof(*id), GFP_KERNEL);
        if (!id) {
                status = NVME_SC_INTERNAL;
                goto out;
        }

        memset(id->fr, ' ', sizeof(id->fr));
        strncpy((char *)id->fr, UTS_RELEASE, sizeof(id->fr));

        /* no limit on data transfer sizes for now */
        id->mdts = 0;
        id->cntlid = cpu_to_le16(ctrl->cntlid);
        id->ver = cpu_to_le32(ctrl->subsys->ver);
        id->lpa = (1 << 2);

        /* no enforcement soft-limit for maxcmd - pick arbitrary high value */
        id->maxcmd = cpu_to_le16(NVMET_MAX_CMD);

        id->sgls = cpu_to_le32(1 << 0); /* we always support SGLs */
        if (ctrl->ops->has_keyed_sgls)
                id->sgls |= cpu_to_le32(1 << 2);
        if (ctrl->ops->sqe_inline_size)
                id->sgls |= cpu_to_le32(1 << 20);

        strcpy(id->subnqn, ctrl->subsys->subsysnqn);

        status = nvmet_copy_to_sgl(req, 0, id, sizeof(*id));

        kfree(id);
out:
        nvmet_req_complete(req, status);
}

int nvmet_parse_discovery_cmd(struct nvmet_req *req)
{
        struct nvme_command *cmd = req->cmd;

        req->ns = NULL;

        if (unlikely(!(req->sq->ctrl->csts & NVME_CSTS_RDY))) {
                pr_err("nvmet: got cmd %d while not ready\n",
                                cmd->common.opcode);
                return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
        }

        switch (cmd->common.opcode) {
        case nvme_admin_get_log_page:
                req->data_len = nvmet_get_log_page_len(cmd);

                switch (cmd->get_log_page.lid) {
                case NVME_LOG_DISC:
                        req->execute = nvmet_execute_get_disc_log_page;
                        return 0;
                default:
                        pr_err("nvmet: unsupported get_log_page lid %d\n",
                                cmd->get_log_page.lid);
                return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
                }
        case nvme_admin_identify:
                req->data_len = 4096;
                switch (le32_to_cpu(cmd->identify.cns)) {
                case NVME_ID_CNS_CTRL:
                        req->execute =
                                nvmet_execute_identify_disc_ctrl;
                        return 0;
                default:
                        pr_err("nvmet: unsupported identify cns %d\n",
                                le32_to_cpu(cmd->identify.cns));
                        return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
                }
        default:
                pr_err("nvmet: unsupported cmd %d\n",
                                cmd->common.opcode);
                return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
        }

        pr_err("nvmet: unhandled cmd %d\n", cmd->common.opcode);
        return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
}

int __init nvmet_init_discovery(void)
{
        nvmet_disc_subsys =
                nvmet_subsys_alloc(NVME_DISC_SUBSYS_NAME, NVME_NQN_DISC);
        if (!nvmet_disc_subsys)
                return -ENOMEM;
        return 0;
}

void nvmet_exit_discovery(void)
{
        nvmet_subsys_put(nvmet_disc_subsys);
}