/*
 * NVMe over Fabrics RDMA target.
 * Copyright (c) 2015-2016 HGST, a Western Digital Company.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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/atomic.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/nvme.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/wait.h>
#include <linux/inet.h>
#include <asm/unaligned.h>

#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
#include <rdma/rw.h>

#include <linux/nvme-rdma.h>
#include "nvmet.h"

/*
 * We allow at least 1 page, up to 4 SGEs, and up to 16KB of inline data
 */
#define NVMET_RDMA_DEFAULT_INLINE_DATA_SIZE     PAGE_SIZE
#define NVMET_RDMA_MAX_INLINE_SGE               4
#define NVMET_RDMA_MAX_INLINE_DATA_SIZE         max_t(int, SZ_16K, PAGE_SIZE)

struct nvmet_rdma_cmd {
        struct ib_sge           sge[NVMET_RDMA_MAX_INLINE_SGE + 1];
        struct ib_cqe           cqe;
        struct ib_recv_wr       wr;
        struct scatterlist      inline_sg[NVMET_RDMA_MAX_INLINE_SGE];
        struct nvme_command     *nvme_cmd;
        struct nvmet_rdma_queue *queue;
};

enum {
        NVMET_RDMA_REQ_INLINE_DATA      = (1 << 0),
        NVMET_RDMA_REQ_INVALIDATE_RKEY  = (1 << 1),
};

struct nvmet_rdma_rsp {
        struct ib_sge           send_sge;
        struct ib_cqe           send_cqe;
        struct ib_send_wr       send_wr;

        struct nvmet_rdma_cmd   *cmd;
        struct nvmet_rdma_queue *queue;

        struct ib_cqe           read_cqe;
        struct rdma_rw_ctx      rw;

        struct nvmet_req        req;

        bool                    allocated;
        u8                      n_rdma;
        u32                     flags;
        u32                     invalidate_rkey;

        struct list_head        wait_list;
        struct list_head        free_list;
};

enum nvmet_rdma_queue_state {
        NVMET_RDMA_Q_CONNECTING,
        NVMET_RDMA_Q_LIVE,
        NVMET_RDMA_Q_DISCONNECTING,
};

struct nvmet_rdma_queue {
        struct rdma_cm_id       *cm_id;
        struct nvmet_port       *port;
        struct ib_cq            *cq;
        atomic_t                sq_wr_avail;
        struct nvmet_rdma_device *dev;
        spinlock_t              state_lock;
        enum nvmet_rdma_queue_state state;
        struct nvmet_cq         nvme_cq;
        struct nvmet_sq         nvme_sq;

        struct nvmet_rdma_rsp   *rsps;
        struct list_head        free_rsps;
        spinlock_t              rsps_lock;
        struct nvmet_rdma_cmd   *cmds;

        struct work_struct      release_work;
        struct list_head        rsp_wait_list;
        struct list_head        rsp_wr_wait_list;
        spinlock_t              rsp_wr_wait_lock;

        int                     idx;
        int                     host_qid;
        int                     recv_queue_size;
        int                     send_queue_size;

        struct list_head        queue_list;
};

struct nvmet_rdma_device {
        struct ib_device        *device;
        struct ib_pd            *pd;
        struct ib_srq           *srq;
        struct nvmet_rdma_cmd   *srq_cmds;
        size_t                  srq_size;
        struct kref             ref;
        struct list_head        entry;
        int                     inline_data_size;
        int                     inline_page_count;
};

static bool nvmet_rdma_use_srq;
module_param_named(use_srq, nvmet_rdma_use_srq, bool, 0444);
MODULE_PARM_DESC(use_srq, "Use shared receive queue.");

static DEFINE_IDA(nvmet_rdma_queue_ida);
static LIST_HEAD(nvmet_rdma_queue_list);
static DEFINE_MUTEX(nvmet_rdma_queue_mutex);

static LIST_HEAD(device_list);
static DEFINE_MUTEX(device_list_mutex);

static bool nvmet_rdma_execute_command(struct nvmet_rdma_rsp *rsp);
static void nvmet_rdma_send_done(struct ib_cq *cq, struct ib_wc *wc);
static void nvmet_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc);
static void nvmet_rdma_read_data_done(struct ib_cq *cq, struct ib_wc *wc);
static void nvmet_rdma_qp_event(struct ib_event *event, void *priv);
static void nvmet_rdma_queue_disconnect(struct nvmet_rdma_queue *queue);

static const struct nvmet_fabrics_ops nvmet_rdma_ops;

static int num_pages(int len)
{
        return 1 + (((len - 1) & PAGE_MASK) >> PAGE_SHIFT);
}

/* XXX: really should move to a generic header sooner or later.. */
static inline u32 get_unaligned_le24(const u8 *p)
{
        return (u32)p[0] | (u32)p[1] << 8 | (u32)p[2] << 16;
}

static inline bool nvmet_rdma_need_data_in(struct nvmet_rdma_rsp *rsp)
{
        return nvme_is_write(rsp->req.cmd) &&
                rsp->req.transfer_len &&
                !(rsp->flags & NVMET_RDMA_REQ_INLINE_DATA);
}

static inline bool nvmet_rdma_need_data_out(struct nvmet_rdma_rsp *rsp)
{
        return !nvme_is_write(rsp->req.cmd) &&
                rsp->req.transfer_len &&
                !rsp->req.rsp->status &&
                !(rsp->flags & NVMET_RDMA_REQ_INLINE_DATA);
}

static inline struct nvmet_rdma_rsp *
nvmet_rdma_get_rsp(struct nvmet_rdma_queue *queue)
{
        struct nvmet_rdma_rsp *rsp;
        unsigned long flags;

        spin_lock_irqsave(&queue->rsps_lock, flags);
        rsp = list_first_entry_or_null(&queue->free_rsps,
                                struct nvmet_rdma_rsp, free_list);
        if (likely(rsp))
                list_del(&rsp->free_list);
        spin_unlock_irqrestore(&queue->rsps_lock, flags);

        if (unlikely(!rsp)) {
                rsp = kmalloc(sizeof(*rsp), GFP_KERNEL);
                if (unlikely(!rsp))
                        return NULL;
                rsp->allocated = true;
        }

        return rsp;
}

static inline void
nvmet_rdma_put_rsp(struct nvmet_rdma_rsp *rsp)
{
        unsigned long flags;

        if (rsp->allocated) {
                kfree(rsp);
                return;
        }

        spin_lock_irqsave(&rsp->queue->rsps_lock, flags);
        list_add_tail(&rsp->free_list, &rsp->queue->free_rsps);
        spin_unlock_irqrestore(&rsp->queue->rsps_lock, flags);
}

static void nvmet_rdma_free_inline_pages(struct nvmet_rdma_device *ndev,
                                struct nvmet_rdma_cmd *c)
{
        struct scatterlist *sg;
        struct ib_sge *sge;
        int i;

        if (!ndev->inline_data_size)
                return;

        sg = c->inline_sg;
        sge = &c->sge[1];

        for (i = 0; i < ndev->inline_page_count; i++, sg++, sge++) {
                if (sge->length)
                        ib_dma_unmap_page(ndev->device, sge->addr,
                                        sge->length, DMA_FROM_DEVICE);
                if (sg_page(sg))
                        __free_page(sg_page(sg));
        }
}

static int nvmet_rdma_alloc_inline_pages(struct nvmet_rdma_device *ndev,
                                struct nvmet_rdma_cmd *c)
{
        struct scatterlist *sg;
        struct ib_sge *sge;
        struct page *pg;
        int len;
        int i;

        if (!ndev->inline_data_size)
                return 0;

        sg = c->inline_sg;
        sg_init_table(sg, ndev->inline_page_count);
        sge = &c->sge[1];
        len = ndev->inline_data_size;

        for (i = 0; i < ndev->inline_page_count; i++, sg++, sge++) {
                pg = alloc_page(GFP_KERNEL);
                if (!pg)
                        goto out_err;
                sg_assign_page(sg, pg);
                sge->addr = ib_dma_map_page(ndev->device,
                        pg, 0, PAGE_SIZE, DMA_FROM_DEVICE);
                if (ib_dma_mapping_error(ndev->device, sge->addr))
                        goto out_err;
                sge->length = min_t(int, len, PAGE_SIZE);
                sge->lkey = ndev->pd->local_dma_lkey;
                len -= sge->length;
        }

        return 0;
out_err:
        for (; i >= 0; i--, sg--, sge--) {
                if (sge->length)
                        ib_dma_unmap_page(ndev->device, sge->addr,
                                        sge->length, DMA_FROM_DEVICE);
                if (sg_page(sg))
                        __free_page(sg_page(sg));
        }
        return -ENOMEM;
}

static int nvmet_rdma_alloc_cmd(struct nvmet_rdma_device *ndev,
                        struct nvmet_rdma_cmd *c, bool admin)
{
        /* NVMe command / RDMA RECV */
        c->nvme_cmd = kmalloc(sizeof(*c->nvme_cmd), GFP_KERNEL);
        if (!c->nvme_cmd)
                goto out;

        c->sge[0].addr = ib_dma_map_single(ndev->device, c->nvme_cmd,
                        sizeof(*c->nvme_cmd), DMA_FROM_DEVICE);
        if (ib_dma_mapping_error(ndev->device, c->sge[0].addr))
                goto out_free_cmd;

        c->sge[0].length = sizeof(*c->nvme_cmd);
        c->sge[0].lkey = ndev->pd->local_dma_lkey;

        if (!admin && nvmet_rdma_alloc_inline_pages(ndev, c))
                goto out_unmap_cmd;

        c->cqe.done = nvmet_rdma_recv_done;

        c->wr.wr_cqe = &c->cqe;
        c->wr.sg_list = c->sge;
        c->wr.num_sge = admin ? 1 : ndev->inline_page_count + 1;

        return 0;

out_unmap_cmd:
        ib_dma_unmap_single(ndev->device, c->sge[0].addr,
                        sizeof(*c->nvme_cmd), DMA_FROM_DEVICE);
out_free_cmd:
        kfree(c->nvme_cmd);

out:
        return -ENOMEM;
}

static void nvmet_rdma_free_cmd(struct nvmet_rdma_device *ndev,
                struct nvmet_rdma_cmd *c, bool admin)
{
        if (!admin)
                nvmet_rdma_free_inline_pages(ndev, c);
        ib_dma_unmap_single(ndev->device, c->sge[0].addr,
                                sizeof(*c->nvme_cmd), DMA_FROM_DEVICE);
        kfree(c->nvme_cmd);
}

static struct nvmet_rdma_cmd *
nvmet_rdma_alloc_cmds(struct nvmet_rdma_device *ndev,
                int nr_cmds, bool admin)
{
        struct nvmet_rdma_cmd *cmds;
        int ret = -EINVAL, i;

        cmds = kcalloc(nr_cmds, sizeof(struct nvmet_rdma_cmd), GFP_KERNEL);
        if (!cmds)
                goto out;

        for (i = 0; i < nr_cmds; i++) {
                ret = nvmet_rdma_alloc_cmd(ndev, cmds + i, admin);
                if (ret)
                        goto out_free;
        }

        return cmds;

out_free:
        while (--i >= 0)
                nvmet_rdma_free_cmd(ndev, cmds + i, admin);
        kfree(cmds);
out:
        return ERR_PTR(ret);
}

static void nvmet_rdma_free_cmds(struct nvmet_rdma_device *ndev,
                struct nvmet_rdma_cmd *cmds, int nr_cmds, bool admin)
{
        int i;

        for (i = 0; i < nr_cmds; i++)
                nvmet_rdma_free_cmd(ndev, cmds + i, admin);
        kfree(cmds);
}

static int nvmet_rdma_alloc_rsp(struct nvmet_rdma_device *ndev,
                struct nvmet_rdma_rsp *r)
{
        /* NVMe CQE / RDMA SEND */
        r->req.rsp = kmalloc(sizeof(*r->req.rsp), GFP_KERNEL);
        if (!r->req.rsp)
                goto out;

        r->send_sge.addr = ib_dma_map_single(ndev->device, r->req.rsp,
                        sizeof(*r->req.rsp), DMA_TO_DEVICE);
        if (ib_dma_mapping_error(ndev->device, r->send_sge.addr))
                goto out_free_rsp;

        r->send_sge.length = sizeof(*r->req.rsp);
        r->send_sge.lkey = ndev->pd->local_dma_lkey;

        r->send_cqe.done = nvmet_rdma_send_done;

        r->send_wr.wr_cqe = &r->send_cqe;
        r->send_wr.sg_list = &r->send_sge;
        r->send_wr.num_sge = 1;
        r->send_wr.send_flags = IB_SEND_SIGNALED;

        /* Data In / RDMA READ */
        r->read_cqe.done = nvmet_rdma_read_data_done;
        return 0;

out_free_rsp:
        kfree(r->req.rsp);
out:
        return -ENOMEM;
}

static void nvmet_rdma_free_rsp(struct nvmet_rdma_device *ndev,
                struct nvmet_rdma_rsp *r)
{
        ib_dma_unmap_single(ndev->device, r->send_sge.addr,
                                sizeof(*r->req.rsp), DMA_TO_DEVICE);
        kfree(r->req.rsp);
}

static int
nvmet_rdma_alloc_rsps(struct nvmet_rdma_queue *queue)
{
        struct nvmet_rdma_device *ndev = queue->dev;
        int nr_rsps = queue->recv_queue_size * 2;
        int ret = -EINVAL, i;

        queue->rsps = kcalloc(nr_rsps, sizeof(struct nvmet_rdma_rsp),
                        GFP_KERNEL);
        if (!queue->rsps)
                goto out;

        for (i = 0; i < nr_rsps; i++) {
                struct nvmet_rdma_rsp *rsp = &queue->rsps[i];

                ret = nvmet_rdma_alloc_rsp(ndev, rsp);
                if (ret)
                        goto out_free;

                list_add_tail(&rsp->free_list, &queue->free_rsps);
        }

        return 0;

out_free:
        while (--i >= 0) {
                struct nvmet_rdma_rsp *rsp = &queue->rsps[i];

                list_del(&rsp->free_list);
                nvmet_rdma_free_rsp(ndev, rsp);
        }
        kfree(queue->rsps);
out:
        return ret;
}

static void nvmet_rdma_free_rsps(struct nvmet_rdma_queue *queue)
{
        struct nvmet_rdma_device *ndev = queue->dev;
        int i, nr_rsps = queue->recv_queue_size * 2;

        for (i = 0; i < nr_rsps; i++) {
                struct nvmet_rdma_rsp *rsp = &queue->rsps[i];

                list_del(&rsp->free_list);
                nvmet_rdma_free_rsp(ndev, rsp);
        }
        kfree(queue->rsps);
}

static int nvmet_rdma_post_recv(struct nvmet_rdma_device *ndev,
                struct nvmet_rdma_cmd *cmd)
{
        int ret;

        ib_dma_sync_single_for_device(ndev->device,
                cmd->sge[0].addr, cmd->sge[0].length,
                DMA_FROM_DEVICE);

        if (ndev->srq)
                ret = ib_post_srq_recv(ndev->srq, &cmd->wr, NULL);
        else
                ret = ib_post_recv(cmd->queue->cm_id->qp, &cmd->wr, NULL);

        if (unlikely(ret))
                pr_err("post_recv cmd failed\n");

        return ret;
}

static void nvmet_rdma_process_wr_wait_list(struct nvmet_rdma_queue *queue)
{
        spin_lock(&queue->rsp_wr_wait_lock);
        while (!list_empty(&queue->rsp_wr_wait_list)) {
                struct nvmet_rdma_rsp *rsp;
                bool ret;

                rsp = list_entry(queue->rsp_wr_wait_list.next,
                                struct nvmet_rdma_rsp, wait_list);
                list_del(&rsp->wait_list);

                spin_unlock(&queue->rsp_wr_wait_lock);
                ret = nvmet_rdma_execute_command(rsp);
                spin_lock(&queue->rsp_wr_wait_lock);

                if (!ret) {
                        list_add(&rsp->wait_list, &queue->rsp_wr_wait_list);
                        break;
                }
        }
        spin_unlock(&queue->rsp_wr_wait_lock);
}


static void nvmet_rdma_release_rsp(struct nvmet_rdma_rsp *rsp)
{
        struct nvmet_rdma_queue *queue = rsp->queue;

        atomic_add(1 + rsp->n_rdma, &queue->sq_wr_avail);

        if (rsp->n_rdma) {
                rdma_rw_ctx_destroy(&rsp->rw, queue->cm_id->qp,
                                queue->cm_id->port_num, rsp->req.sg,
                                rsp->req.sg_cnt, nvmet_data_dir(&rsp->req));
        }

        if (rsp->req.sg != rsp->cmd->inline_sg)
                sgl_free(rsp->req.sg);

        if (unlikely(!list_empty_careful(&queue->rsp_wr_wait_list)))
                nvmet_rdma_process_wr_wait_list(queue);

        nvmet_rdma_put_rsp(rsp);
}

static void nvmet_rdma_error_comp(struct nvmet_rdma_queue *queue)
{
        if (queue->nvme_sq.ctrl) {
                nvmet_ctrl_fatal_error(queue->nvme_sq.ctrl);
        } else {
                /*
                 * we didn't setup the controller yet in case
                 * of admin connect error, just disconnect and
                 * cleanup the queue
                 */
                nvmet_rdma_queue_disconnect(queue);
        }
}

static void nvmet_rdma_send_done(struct ib_cq *cq, struct ib_wc *wc)
{
        struct nvmet_rdma_rsp *rsp =
                container_of(wc->wr_cqe, struct nvmet_rdma_rsp, send_cqe);

        nvmet_rdma_release_rsp(rsp);

        if (unlikely(wc->status != IB_WC_SUCCESS &&
                     wc->status != IB_WC_WR_FLUSH_ERR)) {
                pr_err("SEND for CQE 0x%p failed with status %s (%d).\n",
                        wc->wr_cqe, ib_wc_status_msg(wc->status), wc->status);
                nvmet_rdma_error_comp(rsp->queue);
        }
}

static void nvmet_rdma_queue_response(struct nvmet_req *req)
{
        struct nvmet_rdma_rsp *rsp =
                container_of(req, struct nvmet_rdma_rsp, req);
        struct rdma_cm_id *cm_id = rsp->queue->cm_id;
        struct ib_send_wr *first_wr;

        if (rsp->flags & NVMET_RDMA_REQ_INVALIDATE_RKEY) {
                rsp->send_wr.opcode = IB_WR_SEND_WITH_INV;
                rsp->send_wr.ex.invalidate_rkey = rsp->invalidate_rkey;
        } else {
                rsp->send_wr.opcode = IB_WR_SEND;
        }

        if (nvmet_rdma_need_data_out(rsp))
                first_wr = rdma_rw_ctx_wrs(&rsp->rw, cm_id->qp,
                                cm_id->port_num, NULL, &rsp->send_wr);
        else
                first_wr = &rsp->send_wr;

        nvmet_rdma_post_recv(rsp->queue->dev, rsp->cmd);

        ib_dma_sync_single_for_device(rsp->queue->dev->device,
                rsp->send_sge.addr, rsp->send_sge.length,
                DMA_TO_DEVICE);

        if (unlikely(ib_post_send(cm_id->qp, first_wr, NULL))) {
                pr_err("sending cmd response failed\n");
                nvmet_rdma_release_rsp(rsp);
        }
}

static void nvmet_rdma_read_data_done(struct ib_cq *cq, struct ib_wc *wc)
{
        struct nvmet_rdma_rsp *rsp =
                container_of(wc->wr_cqe, struct nvmet_rdma_rsp, read_cqe);
        struct nvmet_rdma_queue *queue = cq->cq_context;

        WARN_ON(rsp->n_rdma <= 0);
        atomic_add(rsp->n_rdma, &queue->sq_wr_avail);
        rdma_rw_ctx_destroy(&rsp->rw, queue->cm_id->qp,
                        queue->cm_id->port_num, rsp->req.sg,
                        rsp->req.sg_cnt, nvmet_data_dir(&rsp->req));
        rsp->n_rdma = 0;

        if (unlikely(wc->status != IB_WC_SUCCESS)) {
                nvmet_req_uninit(&rsp->req);
                nvmet_rdma_release_rsp(rsp);
                if (wc->status != IB_WC_WR_FLUSH_ERR) {
                        pr_info("RDMA READ for CQE 0x%p failed with status %s (%d).\n",
                                wc->wr_cqe, ib_wc_status_msg(wc->status), wc->status);
                        nvmet_rdma_error_comp(queue);
                }
                return;
        }

        nvmet_req_execute(&rsp->req);
}

static void nvmet_rdma_use_inline_sg(struct nvmet_rdma_rsp *rsp, u32 len,
                u64 off)
{
        int sg_count = num_pages(len);
        struct scatterlist *sg;
        int i;

        sg = rsp->cmd->inline_sg;
        for (i = 0; i < sg_count; i++, sg++) {
                if (i < sg_count - 1)
                        sg_unmark_end(sg);
                else
                        sg_mark_end(sg);
                sg->offset = off;
                sg->length = min_t(int, len, PAGE_SIZE - off);
                len -= sg->length;
                if (!i)
                        off = 0;
        }

        rsp->req.sg = rsp->cmd->inline_sg;
        rsp->req.sg_cnt = sg_count;
}

static u16 nvmet_rdma_map_sgl_inline(struct nvmet_rdma_rsp *rsp)
{
        struct nvme_sgl_desc *sgl = &rsp->req.cmd->common.dptr.sgl;
        u64 off = le64_to_cpu(sgl->addr);
        u32 len = le32_to_cpu(sgl->length);

        if (!nvme_is_write(rsp->req.cmd))
                return NVME_SC_INVALID_FIELD | NVME_SC_DNR;

        if (off + len > rsp->queue->dev->inline_data_size) {
                pr_err("invalid inline data offset!\n");
                return NVME_SC_SGL_INVALID_OFFSET | NVME_SC_DNR;
        }

        /* no data command? */
        if (!len)
                return 0;

        nvmet_rdma_use_inline_sg(rsp, len, off);
        rsp->flags |= NVMET_RDMA_REQ_INLINE_DATA;
        rsp->req.transfer_len += len;
        return 0;
}

static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
                struct nvme_keyed_sgl_desc *sgl, bool invalidate)
{
        struct rdma_cm_id *cm_id = rsp->queue->cm_id;
        u64 addr = le64_to_cpu(sgl->addr);
        u32 len = get_unaligned_le24(sgl->length);
        u32 key = get_unaligned_le32(sgl->key);
        int ret;

        /* no data command? */
        if (!len)
                return 0;

        rsp->req.sg = sgl_alloc(len, GFP_KERNEL, &rsp->req.sg_cnt);
        if (!rsp->req.sg)
                return NVME_SC_INTERNAL;

        ret = rdma_rw_ctx_init(&rsp->rw, cm_id->qp, cm_id->port_num,
                        rsp->req.sg, rsp->req.sg_cnt, 0, addr, key,
                        nvmet_data_dir(&rsp->req));
        if (ret < 0)
                return NVME_SC_INTERNAL;
        rsp->req.transfer_len += len;
        rsp->n_rdma += ret;

        if (invalidate) {
                rsp->invalidate_rkey = key;
                rsp->flags |= NVMET_RDMA_REQ_INVALIDATE_RKEY;
        }

        return 0;
}

static u16 nvmet_rdma_map_sgl(struct nvmet_rdma_rsp *rsp)
{
        struct nvme_keyed_sgl_desc *sgl = &rsp->req.cmd->common.dptr.ksgl;

        switch (sgl->type >> 4) {
        case NVME_SGL_FMT_DATA_DESC:
                switch (sgl->type & 0xf) {
                case NVME_SGL_FMT_OFFSET:
                        return nvmet_rdma_map_sgl_inline(rsp);
                default:
                        pr_err("invalid SGL subtype: %#x\n", sgl->type);
                        return NVME_SC_INVALID_FIELD | NVME_SC_DNR;
                }
        case NVME_KEY_SGL_FMT_DATA_DESC:
                switch (sgl->type & 0xf) {
                case NVME_SGL_FMT_ADDRESS | NVME_SGL_FMT_INVALIDATE:
                        return nvmet_rdma_map_sgl_keyed(rsp, sgl, true);
                case NVME_SGL_FMT_ADDRESS:
                        return nvmet_rdma_map_sgl_keyed(rsp, sgl, false);
                default:
                        pr_err("invalid SGL subtype: %#x\n", sgl->type);
                        return NVME_SC_INVALID_FIELD | NVME_SC_DNR;
                }
        default:
                pr_err("invalid SGL type: %#x\n", sgl->type);
                return NVME_SC_SGL_INVALID_TYPE | NVME_SC_DNR;
        }
}

static bool nvmet_rdma_execute_command(struct nvmet_rdma_rsp *rsp)
{
        struct nvmet_rdma_queue *queue = rsp->queue;

        if (unlikely(atomic_sub_return(1 + rsp->n_rdma,
                        &queue->sq_wr_avail) < 0)) {
                pr_debug("IB send queue full (needed %d): queue %u cntlid %u\n",
                                1 + rsp->n_rdma, queue->idx,
                                queue->nvme_sq.ctrl->cntlid);
                atomic_add(1 + rsp->n_rdma, &queue->sq_wr_avail);
                return false;
        }

        if (nvmet_rdma_need_data_in(rsp)) {
                if (rdma_rw_ctx_post(&rsp->rw, queue->cm_id->qp,
                                queue->cm_id->port_num, &rsp->read_cqe, NULL))
                        nvmet_req_complete(&rsp->req, NVME_SC_DATA_XFER_ERROR);
        } else {
                nvmet_req_execute(&rsp->req);
        }

        return true;
}

static void nvmet_rdma_handle_command(struct nvmet_rdma_queue *queue,
                struct nvmet_rdma_rsp *cmd)
{
        u16 status;

        ib_dma_sync_single_for_cpu(queue->dev->device,
                cmd->cmd->sge[0].addr, cmd->cmd->sge[0].length,
                DMA_FROM_DEVICE);
        ib_dma_sync_single_for_cpu(queue->dev->device,
                cmd->send_sge.addr, cmd->send_sge.length,
                DMA_TO_DEVICE);

        if (!nvmet_req_init(&cmd->req, &queue->nvme_cq,
                        &queue->nvme_sq, &nvmet_rdma_ops))
                return;

        status = nvmet_rdma_map_sgl(cmd);
        if (status)
                goto out_err;

        if (unlikely(!nvmet_rdma_execute_command(cmd))) {
                spin_lock(&queue->rsp_wr_wait_lock);
                list_add_tail(&cmd->wait_list, &queue->rsp_wr_wait_list);
                spin_unlock(&queue->rsp_wr_wait_lock);
        }

        return;

out_err:
        nvmet_req_complete(&cmd->req, status);
}

static void nvmet_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc)
{
        struct nvmet_rdma_cmd *cmd =
                container_of(wc->wr_cqe, struct nvmet_rdma_cmd, cqe);
        struct nvmet_rdma_queue *queue = cq->cq_context;
        struct nvmet_rdma_rsp *rsp;

        if (unlikely(wc->status != IB_WC_SUCCESS)) {
                if (wc->status != IB_WC_WR_FLUSH_ERR) {
                        pr_err("RECV for CQE 0x%p failed with status %s (%d)\n",
                                wc->wr_cqe, ib_wc_status_msg(wc->status),
                                wc->status);
                        nvmet_rdma_error_comp(queue);
                }
                return;
        }

        if (unlikely(wc->byte_len < sizeof(struct nvme_command))) {
                pr_err("Ctrl Fatal Error: capsule size less than 64 bytes\n");
                nvmet_rdma_error_comp(queue);
                return;
        }

        cmd->queue = queue;
        rsp = nvmet_rdma_get_rsp(queue);
        if (unlikely(!rsp)) {
                /*
                 * we get here only under memory pressure,
                 * silently drop and have the host retry
                 * as we can't even fail it.
                 */
                nvmet_rdma_post_recv(queue->dev, cmd);
                return;
        }
        rsp->queue = queue;
        rsp->cmd = cmd;
        rsp->flags = 0;
        rsp->req.cmd = cmd->nvme_cmd;
        rsp->req.port = queue->port;
        rsp->n_rdma = 0;

        if (unlikely(queue->state != NVMET_RDMA_Q_LIVE)) {
                unsigned long flags;

                spin_lock_irqsave(&queue->state_lock, flags);
                if (queue->state == NVMET_RDMA_Q_CONNECTING)
                        list_add_tail(&rsp->wait_list, &queue->rsp_wait_list);
                else
                        nvmet_rdma_put_rsp(rsp);
                spin_unlock_irqrestore(&queue->state_lock, flags);
                return;
        }

        nvmet_rdma_handle_command(queue, rsp);
}

static void nvmet_rdma_destroy_srq(struct nvmet_rdma_device *ndev)
{
        if (!ndev->srq)
                return;

        nvmet_rdma_free_cmds(ndev, ndev->srq_cmds, ndev->srq_size, false);
        ib_destroy_srq(ndev->srq);
}

static int nvmet_rdma_init_srq(struct nvmet_rdma_device *ndev)
{
        struct ib_srq_init_attr srq_attr = { NULL, };
        struct ib_srq *srq;
        size_t srq_size;
        int ret, i;

        srq_size = 4095;        /* XXX: tune */

        srq_attr.attr.max_wr = srq_size;
        srq_attr.attr.max_sge = 1 + ndev->inline_page_count;
        srq_attr.attr.srq_limit = 0;
        srq_attr.srq_type = IB_SRQT_BASIC;
        srq = ib_create_srq(ndev->pd, &srq_attr);
        if (IS_ERR(srq)) {
                /*
                 * If SRQs aren't supported we just go ahead and use normal
                 * non-shared receive queues.
                 */
                pr_info("SRQ requested but not supported.\n");
                return 0;
        }

        ndev->srq_cmds = nvmet_rdma_alloc_cmds(ndev, srq_size, false);
        if (IS_ERR(ndev->srq_cmds)) {
                ret = PTR_ERR(ndev->srq_cmds);
                goto out_destroy_srq;
        }

        ndev->srq = srq;
        ndev->srq_size = srq_size;

        for (i = 0; i < srq_size; i++) {
                ret = nvmet_rdma_post_recv(ndev, &ndev->srq_cmds[i]);
                if (ret)
                        goto out_free_cmds;
        }

        return 0;

out_free_cmds:
        nvmet_rdma_free_cmds(ndev, ndev->srq_cmds, ndev->srq_size, false);
out_destroy_srq:
        ib_destroy_srq(srq);
        return ret;
}

static void nvmet_rdma_free_dev(struct kref *ref)
{
        struct nvmet_rdma_device *ndev =
                container_of(ref, struct nvmet_rdma_device, ref);

        mutex_lock(&device_list_mutex);
        list_del(&ndev->entry);
        mutex_unlock(&device_list_mutex);

        nvmet_rdma_destroy_srq(ndev);
        ib_dealloc_pd(ndev->pd);

        kfree(ndev);
}

static struct nvmet_rdma_device *
nvmet_rdma_find_get_device(struct rdma_cm_id *cm_id)
{
        struct nvmet_port *port = cm_id->context;
        struct nvmet_rdma_device *ndev;
        int inline_page_count;
        int inline_sge_count;
        int ret;

        mutex_lock(&device_list_mutex);
        list_for_each_entry(ndev, &device_list, entry) {
                if (ndev->device->node_guid == cm_id->device->node_guid &&
                    kref_get_unless_zero(&ndev->ref))
                        goto out_unlock;
        }

        ndev = kzalloc(sizeof(*ndev), GFP_KERNEL);
        if (!ndev)
                goto out_err;

        inline_page_count = num_pages(port->inline_data_size);
        inline_sge_count = max(cm_id->device->attrs.max_sge_rd,
                                cm_id->device->attrs.max_recv_sge) - 1;
        if (inline_page_count > inline_sge_count) {
                pr_warn("inline_data_size %d cannot be supported by device %s. Reducing to %lu.\n",
                        port->inline_data_size, cm_id->device->name,
                        inline_sge_count * PAGE_SIZE);
                port->inline_data_size = inline_sge_count * PAGE_SIZE;
                inline_page_count = inline_sge_count;
        }
        ndev->inline_data_size = port->inline_data_size;
        ndev->inline_page_count = inline_page_count;
        ndev->device = cm_id->device;
        kref_init(&ndev->ref);

        ndev->pd = ib_alloc_pd(ndev->device, 0);
        if (IS_ERR(ndev->pd))
                goto out_free_dev;

        if (nvmet_rdma_use_srq) {
                ret = nvmet_rdma_init_srq(ndev);
                if (ret)
                        goto out_free_pd;
        }

        list_add(&ndev->entry, &device_list);
out_unlock:
        mutex_unlock(&device_list_mutex);
        pr_debug("added %s.\n", ndev->device->name);
        return ndev;

out_free_pd:
        ib_dealloc_pd(ndev->pd);
out_free_dev:
        kfree(ndev);
out_err:
        mutex_unlock(&device_list_mutex);
        return NULL;
}

static int nvmet_rdma_create_queue_ib(struct nvmet_rdma_queue *queue)
{
        struct ib_qp_init_attr qp_attr;
        struct nvmet_rdma_device *ndev = queue->dev;
        int comp_vector, nr_cqe, ret, i;

        /*
         * Spread the io queues across completion vectors,
         * but still keep all admin queues on vector 0.
         */
        comp_vector = !queue->host_qid ? 0 :
                queue->idx % ndev->device->num_comp_vectors;

        /*
         * Reserve CQ slots for RECV + RDMA_READ/RDMA_WRITE + RDMA_SEND.
         */
        nr_cqe = queue->recv_queue_size + 2 * queue->send_queue_size;

        queue->cq = ib_alloc_cq(ndev->device, queue,
                        nr_cqe + 1, comp_vector,
                        IB_POLL_WORKQUEUE);
        if (IS_ERR(queue->cq)) {
                ret = PTR_ERR(queue->cq);
                pr_err("failed to create CQ cqe= %d ret= %d\n",
                       nr_cqe + 1, ret);
                goto out;
        }

        memset(&qp_attr, 0, sizeof(qp_attr));
        qp_attr.qp_context = queue;
        qp_attr.event_handler = nvmet_rdma_qp_event;
        qp_attr.send_cq = queue->cq;
        qp_attr.recv_cq = queue->cq;
        qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
        qp_attr.qp_type = IB_QPT_RC;
        /* +1 for drain */
        qp_attr.cap.max_send_wr = queue->send_queue_size + 1;
        qp_attr.cap.max_rdma_ctxs = queue->send_queue_size;
        qp_attr.cap.max_send_sge = max(ndev->device->attrs.max_sge_rd,
                                        ndev->device->attrs.max_send_sge);

        if (ndev->srq) {
                qp_attr.srq = ndev->srq;
        } else {
                /* +1 for drain */
                qp_attr.cap.max_recv_wr = 1 + queue->recv_queue_size;

                qp_attr.cap.max_recv_sge = 1 + ndev->inline_page_count;
        }

        ret = rdma_create_qp(queue->cm_id, ndev->pd, &qp_attr);
        if (ret) {
                pr_err("failed to create_qp ret= %d\n", ret);
                goto err_destroy_cq;
        }

        atomic_set(&queue->sq_wr_avail, qp_attr.cap.max_send_wr);

        pr_debug("%s: max_cqe= %d max_sge= %d sq_size = %d cm_id= %p\n",
                 __func__, queue->cq->cqe, qp_attr.cap.max_send_sge,
                 qp_attr.cap.max_send_wr, queue->cm_id);

        if (!ndev->srq) {
                for (i = 0; i < queue->recv_queue_size; i++) {
                        queue->cmds[i].queue = queue;
                        ret = nvmet_rdma_post_recv(ndev, &queue->cmds[i]);
                        if (ret)
                                goto err_destroy_qp;
                }
        }

out:
        return ret;

err_destroy_qp:
        rdma_destroy_qp(queue->cm_id);
err_destroy_cq:
        ib_free_cq(queue->cq);
        goto out;
}

static void nvmet_rdma_destroy_queue_ib(struct nvmet_rdma_queue *queue)
{
        struct ib_qp *qp = queue->cm_id->qp;

        ib_drain_qp(qp);
        rdma_destroy_id(queue->cm_id);
        ib_destroy_qp(qp);
        ib_free_cq(queue->cq);
}

static void nvmet_rdma_free_queue(struct nvmet_rdma_queue *queue)
{
        pr_debug("freeing queue %d\n", queue->idx);

        nvmet_sq_destroy(&queue->nvme_sq);

        nvmet_rdma_destroy_queue_ib(queue);
        if (!queue->dev->srq) {
                nvmet_rdma_free_cmds(queue->dev, queue->cmds,
                                queue->recv_queue_size,
                                !queue->host_qid);
        }
        nvmet_rdma_free_rsps(queue);
        ida_simple_remove(&nvmet_rdma_queue_ida, queue->idx);
        kfree(queue);
}

static void nvmet_rdma_release_queue_work(struct work_struct *w)
{
        struct nvmet_rdma_queue *queue =
                container_of(w, struct nvmet_rdma_queue, release_work);
        struct nvmet_rdma_device *dev = queue->dev;

        nvmet_rdma_free_queue(queue);

        kref_put(&dev->ref, nvmet_rdma_free_dev);
}

static int
nvmet_rdma_parse_cm_connect_req(struct rdma_conn_param *conn,
                                struct nvmet_rdma_queue *queue)
{
        struct nvme_rdma_cm_req *req;

        req = (struct nvme_rdma_cm_req *)conn->private_data;
        if (!req || conn->private_data_len == 0)
                return NVME_RDMA_CM_INVALID_LEN;

        if (le16_to_cpu(req->recfmt) != NVME_RDMA_CM_FMT_1_0)
                return NVME_RDMA_CM_INVALID_RECFMT;

        queue->host_qid = le16_to_cpu(req->qid);

        /*
         * req->hsqsize corresponds to our recv queue size plus 1
         * req->hrqsize corresponds to our send queue size
         */
        queue->recv_queue_size = le16_to_cpu(req->hsqsize) + 1;
        queue->send_queue_size = le16_to_cpu(req->hrqsize);

        if (!queue->host_qid && queue->recv_queue_size > NVME_AQ_DEPTH)
                return NVME_RDMA_CM_INVALID_HSQSIZE;

        /* XXX: Should we enforce some kind of max for IO queues? */

        return 0;
}

static int nvmet_rdma_cm_reject(struct rdma_cm_id *cm_id,
                                enum nvme_rdma_cm_status status)
{
        struct nvme_rdma_cm_rej rej;

        pr_debug("rejecting connect request: status %d (%s)\n",
                 status, nvme_rdma_cm_msg(status));

        rej.recfmt = cpu_to_le16(NVME_RDMA_CM_FMT_1_0);
        rej.sts = cpu_to_le16(status);

        return rdma_reject(cm_id, (void *)&rej, sizeof(rej));
}

static struct nvmet_rdma_queue *
nvmet_rdma_alloc_queue(struct nvmet_rdma_device *ndev,
                struct rdma_cm_id *cm_id,
                struct rdma_cm_event *event)
{
        struct nvmet_rdma_queue *queue;
        int ret;

        queue = kzalloc(sizeof(*queue), GFP_KERNEL);
        if (!queue) {
                ret = NVME_RDMA_CM_NO_RSC;
                goto out_reject;
        }

        ret = nvmet_sq_init(&queue->nvme_sq);
        if (ret) {
                ret = NVME_RDMA_CM_NO_RSC;
                goto out_free_queue;
        }

        ret = nvmet_rdma_parse_cm_connect_req(&event->param.conn, queue);
        if (ret)
                goto out_destroy_sq;

        /*
         * Schedules the actual release because calling rdma_destroy_id from
         * inside a CM callback would trigger a deadlock. (great API design..)
         */
        INIT_WORK(&queue->release_work, nvmet_rdma_release_queue_work);
        queue->dev = ndev;
        queue->cm_id = cm_id;

        spin_lock_init(&queue->state_lock);
        queue->state = NVMET_RDMA_Q_CONNECTING;
        INIT_LIST_HEAD(&queue->rsp_wait_list);
        INIT_LIST_HEAD(&queue->rsp_wr_wait_list);
        spin_lock_init(&queue->rsp_wr_wait_lock);
        INIT_LIST_HEAD(&queue->free_rsps);
        spin_lock_init(&queue->rsps_lock);
        INIT_LIST_HEAD(&queue->queue_list);

        queue->idx = ida_simple_get(&nvmet_rdma_queue_ida, 0, 0, GFP_KERNEL);
        if (queue->idx < 0) {
                ret = NVME_RDMA_CM_NO_RSC;
                goto out_destroy_sq;
        }

        ret = nvmet_rdma_alloc_rsps(queue);
        if (ret) {
                ret = NVME_RDMA_CM_NO_RSC;
                goto out_ida_remove;
        }

        if (!ndev->srq) {
                queue->cmds = nvmet_rdma_alloc_cmds(ndev,
                                queue->recv_queue_size,
                                !queue->host_qid);
                if (IS_ERR(queue->cmds)) {
                        ret = NVME_RDMA_CM_NO_RSC;
                        goto out_free_responses;
                }
        }

        ret = nvmet_rdma_create_queue_ib(queue);
        if (ret) {
                pr_err("%s: creating RDMA queue failed (%d).\n",
                        __func__, ret);
                ret = NVME_RDMA_CM_NO_RSC;
                goto out_free_cmds;
        }

        return queue;

out_free_cmds:
        if (!ndev->srq) {
                nvmet_rdma_free_cmds(queue->dev, queue->cmds,
                                queue->recv_queue_size,
                                !queue->host_qid);
        }
out_free_responses:
        nvmet_rdma_free_rsps(queue);
out_ida_remove:
        ida_simple_remove(&nvmet_rdma_queue_ida, queue->idx);
out_destroy_sq:
        nvmet_sq_destroy(&queue->nvme_sq);
out_free_queue:
        kfree(queue);
out_reject:
        nvmet_rdma_cm_reject(cm_id, ret);
        return NULL;
}

static void nvmet_rdma_qp_event(struct ib_event *event, void *priv)
{
        struct nvmet_rdma_queue *queue = priv;

        switch (event->event) {
        case IB_EVENT_COMM_EST:
                rdma_notify(queue->cm_id, event->event);
                break;
        default:
                pr_err("received IB QP event: %s (%d)\n",
                       ib_event_msg(event->event), event->event);
                break;
        }
}

static int nvmet_rdma_cm_accept(struct rdma_cm_id *cm_id,
                struct nvmet_rdma_queue *queue,
                struct rdma_conn_param *p)
{
        struct rdma_conn_param  param = { };
        struct nvme_rdma_cm_rep priv = { };
        int ret = -ENOMEM;

        param.rnr_retry_count = 7;
        param.flow_control = 1;
        param.initiator_depth = min_t(u8, p->initiator_depth,
                queue->dev->device->attrs.max_qp_init_rd_atom);
        param.private_data = &priv;
        param.private_data_len = sizeof(priv);
        priv.recfmt = cpu_to_le16(NVME_RDMA_CM_FMT_1_0);
        priv.crqsize = cpu_to_le16(queue->recv_queue_size);

        ret = rdma_accept(cm_id, &param);
        if (ret)
                pr_err("rdma_accept failed (error code = %d)\n", ret);

        return ret;
}

static int nvmet_rdma_queue_connect(struct rdma_cm_id *cm_id,
                struct rdma_cm_event *event)
{
        struct nvmet_rdma_device *ndev;
        struct nvmet_rdma_queue *queue;
        int ret = -EINVAL;

        ndev = nvmet_rdma_find_get_device(cm_id);
        if (!ndev) {
                nvmet_rdma_cm_reject(cm_id, NVME_RDMA_CM_NO_RSC);
                return -ECONNREFUSED;
        }

        queue = nvmet_rdma_alloc_queue(ndev, cm_id, event);
        if (!queue) {
                ret = -ENOMEM;
                goto put_device;
        }
        queue->port = cm_id->context;

        if (queue->host_qid == 0) {
                /* Let inflight controller teardown complete */
                flush_scheduled_work();
        }

        ret = nvmet_rdma_cm_accept(cm_id, queue, &event->param.conn);
        if (ret) {
                schedule_work(&queue->release_work);
                /* Destroying rdma_cm id is not needed here */
                return 0;
        }

        mutex_lock(&nvmet_rdma_queue_mutex);
        list_add_tail(&queue->queue_list, &nvmet_rdma_queue_list);
        mutex_unlock(&nvmet_rdma_queue_mutex);

        return 0;

put_device:
        kref_put(&ndev->ref, nvmet_rdma_free_dev);

        return ret;
}

static void nvmet_rdma_queue_established(struct nvmet_rdma_queue *queue)
{
        unsigned long flags;

        spin_lock_irqsave(&queue->state_lock, flags);
        if (queue->state != NVMET_RDMA_Q_CONNECTING) {
                pr_warn("trying to establish a connected queue\n");
                goto out_unlock;
        }
        queue->state = NVMET_RDMA_Q_LIVE;

        while (!list_empty(&queue->rsp_wait_list)) {
                struct nvmet_rdma_rsp *cmd;

                cmd = list_first_entry(&queue->rsp_wait_list,
                                        struct nvmet_rdma_rsp, wait_list);
                list_del(&cmd->wait_list);

                spin_unlock_irqrestore(&queue->state_lock, flags);
                nvmet_rdma_handle_command(queue, cmd);
                spin_lock_irqsave(&queue->state_lock, flags);
        }

out_unlock:
        spin_unlock_irqrestore(&queue->state_lock, flags);
}

static void __nvmet_rdma_queue_disconnect(struct nvmet_rdma_queue *queue)
{
        bool disconnect = false;
        unsigned long flags;

        pr_debug("cm_id= %p queue->state= %d\n", queue->cm_id, queue->state);

        spin_lock_irqsave(&queue->state_lock, flags);
        switch (queue->state) {
        case NVMET_RDMA_Q_CONNECTING:
        case NVMET_RDMA_Q_LIVE:
                queue->state = NVMET_RDMA_Q_DISCONNECTING;
                disconnect = true;
                break;
        case NVMET_RDMA_Q_DISCONNECTING:
                break;
        }
        spin_unlock_irqrestore(&queue->state_lock, flags);

        if (disconnect) {
                rdma_disconnect(queue->cm_id);
                schedule_work(&queue->release_work);
        }
}

static void nvmet_rdma_queue_disconnect(struct nvmet_rdma_queue *queue)
{
        bool disconnect = false;

        mutex_lock(&nvmet_rdma_queue_mutex);
        if (!list_empty(&queue->queue_list)) {
                list_del_init(&queue->queue_list);
                disconnect = true;
        }
        mutex_unlock(&nvmet_rdma_queue_mutex);

        if (disconnect)
                __nvmet_rdma_queue_disconnect(queue);
}

static void nvmet_rdma_queue_connect_fail(struct rdma_cm_id *cm_id,
                struct nvmet_rdma_queue *queue)
{
        WARN_ON_ONCE(queue->state != NVMET_RDMA_Q_CONNECTING);

        mutex_lock(&nvmet_rdma_queue_mutex);
        if (!list_empty(&queue->queue_list))
                list_del_init(&queue->queue_list);
        mutex_unlock(&nvmet_rdma_queue_mutex);

        pr_err("failed to connect queue %d\n", queue->idx);
        schedule_work(&queue->release_work);
}

/**
 * nvme_rdma_device_removal() - Handle RDMA device removal
 * @cm_id:      rdma_cm id, used for nvmet port
 * @queue:      nvmet rdma queue (cm id qp_context)
 *
 * DEVICE_REMOVAL event notifies us that the RDMA device is about
 * to unplug. Note that this event can be generated on a normal
 * queue cm_id and/or a device bound listener cm_id (where in this
 * case queue will be null).
 *
 * We registered an ib_client to handle device removal for queues,
 * so we only need to handle the listening port cm_ids. In this case
 * we nullify the priv to prevent double cm_id destruction and destroying
 * the cm_id implicitely by returning a non-zero rc to the callout.
 */
static int nvmet_rdma_device_removal(struct rdma_cm_id *cm_id,
                struct nvmet_rdma_queue *queue)
{
        struct nvmet_port *port;

        if (queue) {
                /*
                 * This is a queue cm_id. we have registered
                 * an ib_client to handle queues removal
                 * so don't interfear and just return.
                 */
                return 0;
        }

        port = cm_id->context;

        /*
         * This is a listener cm_id. Make sure that
         * future remove_port won't invoke a double
         * cm_id destroy. use atomic xchg to make sure
         * we don't compete with remove_port.
         */
        if (xchg(&port->priv, NULL) != cm_id)
                return 0;

        /*
         * We need to return 1 so that the core will destroy
         * it's own ID.  What a great API design..
         */
        return 1;
}

static int nvmet_rdma_cm_handler(struct rdma_cm_id *cm_id,
                struct rdma_cm_event *event)
{
        struct nvmet_rdma_queue *queue = NULL;
        int ret = 0;

        if (cm_id->qp)
                queue = cm_id->qp->qp_context;

        pr_debug("%s (%d): status %d id %p\n",
                rdma_event_msg(event->event), event->event,
                event->status, cm_id);

        switch (event->event) {
        case RDMA_CM_EVENT_CONNECT_REQUEST:
                ret = nvmet_rdma_queue_connect(cm_id, event);
                break;
        case RDMA_CM_EVENT_ESTABLISHED:
                nvmet_rdma_queue_established(queue);
                break;
        case RDMA_CM_EVENT_ADDR_CHANGE:
        case RDMA_CM_EVENT_DISCONNECTED:
        case RDMA_CM_EVENT_TIMEWAIT_EXIT:
                nvmet_rdma_queue_disconnect(queue);
                break;
        case RDMA_CM_EVENT_DEVICE_REMOVAL:
                ret = nvmet_rdma_device_removal(cm_id, queue);
                break;
        case RDMA_CM_EVENT_REJECTED:
                pr_debug("Connection rejected: %s\n",
                         rdma_reject_msg(cm_id, event->status));
                /* FALLTHROUGH */
        case RDMA_CM_EVENT_UNREACHABLE:
        case RDMA_CM_EVENT_CONNECT_ERROR:
                nvmet_rdma_queue_connect_fail(cm_id, queue);
                break;
        default:
                pr_err("received unrecognized RDMA CM event %d\n",
                        event->event);
                break;
        }

        return ret;
}

static void nvmet_rdma_delete_ctrl(struct nvmet_ctrl *ctrl)
{
        struct nvmet_rdma_queue *queue;

restart:
        mutex_lock(&nvmet_rdma_queue_mutex);
        list_for_each_entry(queue, &nvmet_rdma_queue_list, queue_list) {
                if (queue->nvme_sq.ctrl == ctrl) {
                        list_del_init(&queue->queue_list);
                        mutex_unlock(&nvmet_rdma_queue_mutex);

                        __nvmet_rdma_queue_disconnect(queue);
                        goto restart;
                }
        }
        mutex_unlock(&nvmet_rdma_queue_mutex);
}

static int nvmet_rdma_add_port(struct nvmet_port *port)
{
        struct rdma_cm_id *cm_id;
        struct sockaddr_storage addr = { };
        __kernel_sa_family_t af;
        int ret;

        switch (port->disc_addr.adrfam) {
        case NVMF_ADDR_FAMILY_IP4:
                af = AF_INET;
                break;
        case NVMF_ADDR_FAMILY_IP6:
                af = AF_INET6;
                break;
        default:
                pr_err("address family %d not supported\n",
                                port->disc_addr.adrfam);
                return -EINVAL;
        }

        if (port->inline_data_size < 0) {
                port->inline_data_size = NVMET_RDMA_DEFAULT_INLINE_DATA_SIZE;
        } else if (port->inline_data_size > NVMET_RDMA_MAX_INLINE_DATA_SIZE) {
                pr_warn("inline_data_size %u is too large, reducing to %u\n",
                        port->inline_data_size,
                        NVMET_RDMA_MAX_INLINE_DATA_SIZE);
                port->inline_data_size = NVMET_RDMA_MAX_INLINE_DATA_SIZE;
        }

        ret = inet_pton_with_scope(&init_net, af, port->disc_addr.traddr,
                        port->disc_addr.trsvcid, &addr);
        if (ret) {
                pr_err("malformed ip/port passed: %s:%s\n",
                        port->disc_addr.traddr, port->disc_addr.trsvcid);
                return ret;
        }

        cm_id = rdma_create_id(&init_net, nvmet_rdma_cm_handler, port,
                        RDMA_PS_TCP, IB_QPT_RC);
        if (IS_ERR(cm_id)) {
                pr_err("CM ID creation failed\n");
                return PTR_ERR(cm_id);
        }

        /*
         * Allow both IPv4 and IPv6 sockets to bind a single port
         * at the same time.
         */
        ret = rdma_set_afonly(cm_id, 1);
        if (ret) {
                pr_err("rdma_set_afonly failed (%d)\n", ret);
                goto out_destroy_id;
        }

        ret = rdma_bind_addr(cm_id, (struct sockaddr *)&addr);
        if (ret) {
                pr_err("binding CM ID to %pISpcs failed (%d)\n",
                        (struct sockaddr *)&addr, ret);
                goto out_destroy_id;
        }

        ret = rdma_listen(cm_id, 128);
        if (ret) {
                pr_err("listening to %pISpcs failed (%d)\n",
                        (struct sockaddr *)&addr, ret);
                goto out_destroy_id;
        }

        pr_info("enabling port %d (%pISpcs)\n",
                le16_to_cpu(port->disc_addr.portid), (struct sockaddr *)&addr);
        port->priv = cm_id;
        return 0;

out_destroy_id:
        rdma_destroy_id(cm_id);
        return ret;
}

static void nvmet_rdma_remove_port(struct nvmet_port *port)
{
        struct rdma_cm_id *cm_id = xchg(&port->priv, NULL);

        if (cm_id)
                rdma_destroy_id(cm_id);
}

static void nvmet_rdma_disc_port_addr(struct nvmet_req *req,
                struct nvmet_port *port, char *traddr)
{
        struct rdma_cm_id *cm_id = port->priv;

        if (inet_addr_is_any((struct sockaddr *)&cm_id->route.addr.src_addr)) {
                struct nvmet_rdma_rsp *rsp =
                        container_of(req, struct nvmet_rdma_rsp, req);
                struct rdma_cm_id *req_cm_id = rsp->queue->cm_id;
                struct sockaddr *addr = (void *)&req_cm_id->route.addr.src_addr;

                sprintf(traddr, "%pISc", addr);
        } else {
                memcpy(traddr, port->disc_addr.traddr, NVMF_TRADDR_SIZE);
        }
}

static const struct nvmet_fabrics_ops nvmet_rdma_ops = {
        .owner                  = THIS_MODULE,
        .type                   = NVMF_TRTYPE_RDMA,
        .msdbd                  = 1,
        .has_keyed_sgls         = 1,
        .add_port               = nvmet_rdma_add_port,
        .remove_port            = nvmet_rdma_remove_port,
        .queue_response         = nvmet_rdma_queue_response,
        .delete_ctrl            = nvmet_rdma_delete_ctrl,
        .disc_traddr            = nvmet_rdma_disc_port_addr,
};

static void nvmet_rdma_remove_one(struct ib_device *ib_device, void *client_data)
{
        struct nvmet_rdma_queue *queue, *tmp;
        struct nvmet_rdma_device *ndev;
        bool found = false;

        mutex_lock(&device_list_mutex);
        list_for_each_entry(ndev, &device_list, entry) {
                if (ndev->device == ib_device) {
                        found = true;
                        break;
                }
        }
        mutex_unlock(&device_list_mutex);

        if (!found)
                return;

        /*
         * IB Device that is used by nvmet controllers is being removed,
         * delete all queues using this device.
         */
        mutex_lock(&nvmet_rdma_queue_mutex);
        list_for_each_entry_safe(queue, tmp, &nvmet_rdma_queue_list,
                                 queue_list) {
                if (queue->dev->device != ib_device)
                        continue;

                pr_info("Removing queue %d\n", queue->idx);
                list_del_init(&queue->queue_list);
                __nvmet_rdma_queue_disconnect(queue);
        }
        mutex_unlock(&nvmet_rdma_queue_mutex);

        flush_scheduled_work();
}

static struct ib_client nvmet_rdma_ib_client = {
        .name   = "nvmet_rdma",
        .remove = nvmet_rdma_remove_one
};

static int __init nvmet_rdma_init(void)
{
        int ret;

        ret = ib_register_client(&nvmet_rdma_ib_client);
        if (ret)
                return ret;

        ret = nvmet_register_transport(&nvmet_rdma_ops);
        if (ret)
                goto err_ib_client;

        return 0;

err_ib_client:
        ib_unregister_client(&nvmet_rdma_ib_client);
        return ret;
}

static void __exit nvmet_rdma_exit(void)
{
        nvmet_unregister_transport(&nvmet_rdma_ops);
        ib_unregister_client(&nvmet_rdma_ib_client);
        WARN_ON_ONCE(!list_empty(&nvmet_rdma_queue_list));
        ida_destroy(&nvmet_rdma_queue_ida);
}

module_init(nvmet_rdma_init);
module_exit(nvmet_rdma_exit);

MODULE_LICENSE("GPL v2");
MODULE_ALIAS("nvmet-transport-1"); /* 1 == NVMF_TRTYPE_RDMA */