// SPDX-License-Identifier: GPL-2.0
/*
 * NVMe over Fabrics TCP host.
 * Copyright (c) 2018 Lightbits Labs. All rights reserved.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/nvme-tcp.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <linux/blk-mq.h>
#include <crypto/hash.h>
#include <net/busy_poll.h>

#include "nvme.h"
#include "fabrics.h"

struct nvme_tcp_queue;

/* Define the socket priority to use for connections were it is desirable
 * that the NIC consider performing optimized packet processing or filtering.
 * A non-zero value being sufficient to indicate general consideration of any
 * possible optimization.  Making it a module param allows for alternative
 * values that may be unique for some NIC implementations.
 */
static int so_priority;
module_param(so_priority, int, 0644);
MODULE_PARM_DESC(so_priority, "nvme tcp socket optimize priority");

enum nvme_tcp_send_state {
        NVME_TCP_SEND_CMD_PDU = 0,
        NVME_TCP_SEND_H2C_PDU,
        NVME_TCP_SEND_DATA,
        NVME_TCP_SEND_DDGST,
};

struct nvme_tcp_request {
        struct nvme_request     req;
        void                    *pdu;
        struct nvme_tcp_queue   *queue;
        u32                     data_len;
        u32                     pdu_len;
        u32                     pdu_sent;
        u16                     ttag;
        struct list_head        entry;
        __le32                  ddgst;

        struct bio              *curr_bio;
        struct iov_iter         iter;

        /* send state */
        size_t                  offset;
        size_t                  data_sent;
        enum nvme_tcp_send_state state;
};

enum nvme_tcp_queue_flags {
        NVME_TCP_Q_ALLOCATED    = 0,
        NVME_TCP_Q_LIVE         = 1,
        NVME_TCP_Q_POLLING      = 2,
};

enum nvme_tcp_recv_state {
        NVME_TCP_RECV_PDU = 0,
        NVME_TCP_RECV_DATA,
        NVME_TCP_RECV_DDGST,
};

struct nvme_tcp_ctrl;
struct nvme_tcp_queue {
        struct socket           *sock;
        struct work_struct      io_work;
        int                     io_cpu;

        spinlock_t              lock;
        struct mutex            send_mutex;
        struct list_head        send_list;

        /* recv state */
        void                    *pdu;
        int                     pdu_remaining;
        int                     pdu_offset;
        size_t                  data_remaining;
        size_t                  ddgst_remaining;
        unsigned int            nr_cqe;

        /* send state */
        struct nvme_tcp_request *request;

        int                     queue_size;
        size_t                  cmnd_capsule_len;
        struct nvme_tcp_ctrl    *ctrl;
        unsigned long           flags;
        bool                    rd_enabled;

        bool                    hdr_digest;
        bool                    data_digest;
        struct ahash_request    *rcv_hash;
        struct ahash_request    *snd_hash;
        __le32                  exp_ddgst;
        __le32                  recv_ddgst;

        struct page_frag_cache  pf_cache;

        void (*state_change)(struct sock *);
        void (*data_ready)(struct sock *);
        void (*write_space)(struct sock *);
};

struct nvme_tcp_ctrl {
        /* read only in the hot path */
        struct nvme_tcp_queue   *queues;
        struct blk_mq_tag_set   tag_set;

        /* other member variables */
        struct list_head        list;
        struct blk_mq_tag_set   admin_tag_set;
        struct sockaddr_storage addr;
        struct sockaddr_storage src_addr;
        struct nvme_ctrl        ctrl;

        struct work_struct      err_work;
        struct delayed_work     connect_work;
        struct nvme_tcp_request async_req;
        u32                     io_queues[HCTX_MAX_TYPES];
};

static LIST_HEAD(nvme_tcp_ctrl_list);
static DEFINE_MUTEX(nvme_tcp_ctrl_mutex);
static struct workqueue_struct *nvme_tcp_wq;
static const struct blk_mq_ops nvme_tcp_mq_ops;
static const struct blk_mq_ops nvme_tcp_admin_mq_ops;
static int nvme_tcp_try_send(struct nvme_tcp_queue *queue);

static inline struct nvme_tcp_ctrl *to_tcp_ctrl(struct nvme_ctrl *ctrl)
{
        return container_of(ctrl, struct nvme_tcp_ctrl, ctrl);
}

static inline int nvme_tcp_queue_id(struct nvme_tcp_queue *queue)
{
        return queue - queue->ctrl->queues;
}

static inline struct blk_mq_tags *nvme_tcp_tagset(struct nvme_tcp_queue *queue)
{
        u32 queue_idx = nvme_tcp_queue_id(queue);

        if (queue_idx == 0)
                return queue->ctrl->admin_tag_set.tags[queue_idx];
        return queue->ctrl->tag_set.tags[queue_idx - 1];
}

static inline u8 nvme_tcp_hdgst_len(struct nvme_tcp_queue *queue)
{
        return queue->hdr_digest ? NVME_TCP_DIGEST_LENGTH : 0;
}

static inline u8 nvme_tcp_ddgst_len(struct nvme_tcp_queue *queue)
{
        return queue->data_digest ? NVME_TCP_DIGEST_LENGTH : 0;
}

static inline size_t nvme_tcp_inline_data_size(struct nvme_tcp_queue *queue)
{
        return queue->cmnd_capsule_len - sizeof(struct nvme_command);
}

static inline bool nvme_tcp_async_req(struct nvme_tcp_request *req)
{
        return req == &req->queue->ctrl->async_req;
}

static inline bool nvme_tcp_has_inline_data(struct nvme_tcp_request *req)
{
        struct request *rq;

        if (unlikely(nvme_tcp_async_req(req)))
                return false; /* async events don't have a request */

        rq = blk_mq_rq_from_pdu(req);

        return rq_data_dir(rq) == WRITE && req->data_len &&
                req->data_len <= nvme_tcp_inline_data_size(req->queue);
}

static inline struct page *nvme_tcp_req_cur_page(struct nvme_tcp_request *req)
{
        return req->iter.bvec->bv_page;
}

static inline size_t nvme_tcp_req_cur_offset(struct nvme_tcp_request *req)
{
        return req->iter.bvec->bv_offset + req->iter.iov_offset;
}

static inline size_t nvme_tcp_req_cur_length(struct nvme_tcp_request *req)
{
        return min_t(size_t, req->iter.bvec->bv_len - req->iter.iov_offset,
                        req->pdu_len - req->pdu_sent);
}

static inline size_t nvme_tcp_req_offset(struct nvme_tcp_request *req)
{
        return req->iter.iov_offset;
}

static inline size_t nvme_tcp_pdu_data_left(struct nvme_tcp_request *req)
{
        return rq_data_dir(blk_mq_rq_from_pdu(req)) == WRITE ?
                        req->pdu_len - req->pdu_sent : 0;
}

static inline size_t nvme_tcp_pdu_last_send(struct nvme_tcp_request *req,
                int len)
{
        return nvme_tcp_pdu_data_left(req) <= len;
}

static void nvme_tcp_init_iter(struct nvme_tcp_request *req,
                unsigned int dir)
{
        struct request *rq = blk_mq_rq_from_pdu(req);
        struct bio_vec *vec;
        unsigned int size;
        int nsegs;
        size_t offset;

        if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) {
                vec = &rq->special_vec;
                nsegs = 1;
                size = blk_rq_payload_bytes(rq);
                offset = 0;
        } else {
                struct bio *bio = req->curr_bio;

                vec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
                nsegs = bio_segments(bio);
                size = bio->bi_iter.bi_size;
                offset = bio->bi_iter.bi_bvec_done;
        }

        iov_iter_bvec(&req->iter, dir, vec, nsegs, size);
        req->iter.iov_offset = offset;
}

static inline void nvme_tcp_advance_req(struct nvme_tcp_request *req,
                int len)
{
        req->data_sent += len;
        req->pdu_sent += len;
        iov_iter_advance(&req->iter, len);
        if (!iov_iter_count(&req->iter) &&
            req->data_sent < req->data_len) {
                req->curr_bio = req->curr_bio->bi_next;
                nvme_tcp_init_iter(req, WRITE);
        }
}

static inline void nvme_tcp_queue_request(struct nvme_tcp_request *req,
                bool sync)
{
        struct nvme_tcp_queue *queue = req->queue;
        bool empty;

        spin_lock(&queue->lock);
        empty = list_empty(&queue->send_list) && !queue->request;
        list_add_tail(&req->entry, &queue->send_list);
        spin_unlock(&queue->lock);

        /*
         * if we're the first on the send_list and we can try to send
         * directly, otherwise queue io_work. Also, only do that if we
         * are on the same cpu, so we don't introduce contention.
         */
        if (queue->io_cpu == smp_processor_id() &&
            sync && empty && mutex_trylock(&queue->send_mutex)) {
                nvme_tcp_try_send(queue);
                mutex_unlock(&queue->send_mutex);
        } else {
                queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
        }
}

static inline struct nvme_tcp_request *
nvme_tcp_fetch_request(struct nvme_tcp_queue *queue)
{
        struct nvme_tcp_request *req;

        spin_lock(&queue->lock);
        req = list_first_entry_or_null(&queue->send_list,
                        struct nvme_tcp_request, entry);
        if (req)
                list_del(&req->entry);
        spin_unlock(&queue->lock);

        return req;
}

static inline void nvme_tcp_ddgst_final(struct ahash_request *hash,
                __le32 *dgst)
{
        ahash_request_set_crypt(hash, NULL, (u8 *)dgst, 0);
        crypto_ahash_final(hash);
}

static inline void nvme_tcp_ddgst_update(struct ahash_request *hash,
                struct page *page, off_t off, size_t len)
{
        struct scatterlist sg;

        sg_init_marker(&sg, 1);
        sg_set_page(&sg, page, len, off);
        ahash_request_set_crypt(hash, &sg, NULL, len);
        crypto_ahash_update(hash);
}

static inline void nvme_tcp_hdgst(struct ahash_request *hash,
                void *pdu, size_t len)
{
        struct scatterlist sg;

        sg_init_one(&sg, pdu, len);
        ahash_request_set_crypt(hash, &sg, pdu + len, len);
        crypto_ahash_digest(hash);
}

static int nvme_tcp_verify_hdgst(struct nvme_tcp_queue *queue,
                void *pdu, size_t pdu_len)
{
        struct nvme_tcp_hdr *hdr = pdu;
        __le32 recv_digest;
        __le32 exp_digest;

        if (unlikely(!(hdr->flags & NVME_TCP_F_HDGST))) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d: header digest flag is cleared\n",
                        nvme_tcp_queue_id(queue));
                return -EPROTO;
        }

        recv_digest = *(__le32 *)(pdu + hdr->hlen);
        nvme_tcp_hdgst(queue->rcv_hash, pdu, pdu_len);
        exp_digest = *(__le32 *)(pdu + hdr->hlen);
        if (recv_digest != exp_digest) {
                dev_err(queue->ctrl->ctrl.device,
                        "header digest error: recv %#x expected %#x\n",
                        le32_to_cpu(recv_digest), le32_to_cpu(exp_digest));
                return -EIO;
        }

        return 0;
}

static int nvme_tcp_check_ddgst(struct nvme_tcp_queue *queue, void *pdu)
{
        struct nvme_tcp_hdr *hdr = pdu;
        u8 digest_len = nvme_tcp_hdgst_len(queue);
        u32 len;

        len = le32_to_cpu(hdr->plen) - hdr->hlen -
                ((hdr->flags & NVME_TCP_F_HDGST) ? digest_len : 0);

        if (unlikely(len && !(hdr->flags & NVME_TCP_F_DDGST))) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d: data digest flag is cleared\n",
                nvme_tcp_queue_id(queue));
                return -EPROTO;
        }
        crypto_ahash_init(queue->rcv_hash);

        return 0;
}

static void nvme_tcp_exit_request(struct blk_mq_tag_set *set,
                struct request *rq, unsigned int hctx_idx)
{
        struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);

        page_frag_free(req->pdu);
}

static int nvme_tcp_init_request(struct blk_mq_tag_set *set,
                struct request *rq, unsigned int hctx_idx,
                unsigned int numa_node)
{
        struct nvme_tcp_ctrl *ctrl = set->driver_data;
        struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
        int queue_idx = (set == &ctrl->tag_set) ? hctx_idx + 1 : 0;
        struct nvme_tcp_queue *queue = &ctrl->queues[queue_idx];
        u8 hdgst = nvme_tcp_hdgst_len(queue);

        req->pdu = page_frag_alloc(&queue->pf_cache,
                sizeof(struct nvme_tcp_cmd_pdu) + hdgst,
                GFP_KERNEL | __GFP_ZERO);
        if (!req->pdu)
                return -ENOMEM;

        req->queue = queue;
        nvme_req(rq)->ctrl = &ctrl->ctrl;

        return 0;
}

static int nvme_tcp_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                unsigned int hctx_idx)
{
        struct nvme_tcp_ctrl *ctrl = data;
        struct nvme_tcp_queue *queue = &ctrl->queues[hctx_idx + 1];

        hctx->driver_data = queue;
        return 0;
}

static int nvme_tcp_init_admin_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                unsigned int hctx_idx)
{
        struct nvme_tcp_ctrl *ctrl = data;
        struct nvme_tcp_queue *queue = &ctrl->queues[0];

        hctx->driver_data = queue;
        return 0;
}

static enum nvme_tcp_recv_state
nvme_tcp_recv_state(struct nvme_tcp_queue *queue)
{
        return  (queue->pdu_remaining) ? NVME_TCP_RECV_PDU :
                (queue->ddgst_remaining) ? NVME_TCP_RECV_DDGST :
                NVME_TCP_RECV_DATA;
}

static void nvme_tcp_init_recv_ctx(struct nvme_tcp_queue *queue)
{
        queue->pdu_remaining = sizeof(struct nvme_tcp_rsp_pdu) +
                                nvme_tcp_hdgst_len(queue);
        queue->pdu_offset = 0;
        queue->data_remaining = -1;
        queue->ddgst_remaining = 0;
}

static void nvme_tcp_error_recovery(struct nvme_ctrl *ctrl)
{
        if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
                return;

        queue_work(nvme_reset_wq, &to_tcp_ctrl(ctrl)->err_work);
}

static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
                struct nvme_completion *cqe)
{
        struct request *rq;

        rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), cqe->command_id);
        if (!rq) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d tag 0x%x not found\n",
                        nvme_tcp_queue_id(queue), cqe->command_id);
                nvme_tcp_error_recovery(&queue->ctrl->ctrl);
                return -EINVAL;
        }

        nvme_end_request(rq, cqe->status, cqe->result);
        queue->nr_cqe++;

        return 0;
}

static int nvme_tcp_handle_c2h_data(struct nvme_tcp_queue *queue,
                struct nvme_tcp_data_pdu *pdu)
{
        struct request *rq;

        rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
        if (!rq) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d tag %#x not found\n",
                        nvme_tcp_queue_id(queue), pdu->command_id);
                return -ENOENT;
        }

        if (!blk_rq_payload_bytes(rq)) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d tag %#x unexpected data\n",
                        nvme_tcp_queue_id(queue), rq->tag);
                return -EIO;
        }

        queue->data_remaining = le32_to_cpu(pdu->data_length);

        if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS &&
            unlikely(!(pdu->hdr.flags & NVME_TCP_F_DATA_LAST))) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d tag %#x SUCCESS set but not last PDU\n",
                        nvme_tcp_queue_id(queue), rq->tag);
                nvme_tcp_error_recovery(&queue->ctrl->ctrl);
                return -EPROTO;
        }

        return 0;
}

static int nvme_tcp_handle_comp(struct nvme_tcp_queue *queue,
                struct nvme_tcp_rsp_pdu *pdu)
{
        struct nvme_completion *cqe = &pdu->cqe;
        int ret = 0;

        /*
         * AEN requests are special as they don't time out and can
         * survive any kind of queue freeze and often don't respond to
         * aborts.  We don't even bother to allocate a struct request
         * for them but rather special case them here.
         */
        if (unlikely(nvme_is_aen_req(nvme_tcp_queue_id(queue),
                                     cqe->command_id)))
                nvme_complete_async_event(&queue->ctrl->ctrl, cqe->status,
                                &cqe->result);
        else
                ret = nvme_tcp_process_nvme_cqe(queue, cqe);

        return ret;
}

static int nvme_tcp_setup_h2c_data_pdu(struct nvme_tcp_request *req,
                struct nvme_tcp_r2t_pdu *pdu)
{
        struct nvme_tcp_data_pdu *data = req->pdu;
        struct nvme_tcp_queue *queue = req->queue;
        struct request *rq = blk_mq_rq_from_pdu(req);
        u8 hdgst = nvme_tcp_hdgst_len(queue);
        u8 ddgst = nvme_tcp_ddgst_len(queue);

        req->pdu_len = le32_to_cpu(pdu->r2t_length);
        req->pdu_sent = 0;

        if (unlikely(req->data_sent + req->pdu_len > req->data_len)) {
                dev_err(queue->ctrl->ctrl.device,
                        "req %d r2t len %u exceeded data len %u (%zu sent)\n",
                        rq->tag, req->pdu_len, req->data_len,
                        req->data_sent);
                return -EPROTO;
        }

        if (unlikely(le32_to_cpu(pdu->r2t_offset) < req->data_sent)) {
                dev_err(queue->ctrl->ctrl.device,
                        "req %d unexpected r2t offset %u (expected %zu)\n",
                        rq->tag, le32_to_cpu(pdu->r2t_offset),
                        req->data_sent);
                return -EPROTO;
        }

        memset(data, 0, sizeof(*data));
        data->hdr.type = nvme_tcp_h2c_data;
        data->hdr.flags = NVME_TCP_F_DATA_LAST;
        if (queue->hdr_digest)
                data->hdr.flags |= NVME_TCP_F_HDGST;
        if (queue->data_digest)
                data->hdr.flags |= NVME_TCP_F_DDGST;
        data->hdr.hlen = sizeof(*data);
        data->hdr.pdo = data->hdr.hlen + hdgst;
        data->hdr.plen =
                cpu_to_le32(data->hdr.hlen + hdgst + req->pdu_len + ddgst);
        data->ttag = pdu->ttag;
        data->command_id = rq->tag;
        data->data_offset = cpu_to_le32(req->data_sent);
        data->data_length = cpu_to_le32(req->pdu_len);
        return 0;
}

static int nvme_tcp_handle_r2t(struct nvme_tcp_queue *queue,
                struct nvme_tcp_r2t_pdu *pdu)
{
        struct nvme_tcp_request *req;
        struct request *rq;
        int ret;

        rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
        if (!rq) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d tag %#x not found\n",
                        nvme_tcp_queue_id(queue), pdu->command_id);
                return -ENOENT;
        }
        req = blk_mq_rq_to_pdu(rq);

        ret = nvme_tcp_setup_h2c_data_pdu(req, pdu);
        if (unlikely(ret))
                return ret;

        req->state = NVME_TCP_SEND_H2C_PDU;
        req->offset = 0;

        nvme_tcp_queue_request(req, false);

        return 0;
}

static int nvme_tcp_recv_pdu(struct nvme_tcp_queue *queue, struct sk_buff *skb,
                unsigned int *offset, size_t *len)
{
        struct nvme_tcp_hdr *hdr;
        char *pdu = queue->pdu;
        size_t rcv_len = min_t(size_t, *len, queue->pdu_remaining);
        int ret;

        ret = skb_copy_bits(skb, *offset,
                &pdu[queue->pdu_offset], rcv_len);
        if (unlikely(ret))
                return ret;

        queue->pdu_remaining -= rcv_len;
        queue->pdu_offset += rcv_len;
        *offset += rcv_len;
        *len -= rcv_len;
        if (queue->pdu_remaining)
                return 0;

        hdr = queue->pdu;
        if (queue->hdr_digest) {
                ret = nvme_tcp_verify_hdgst(queue, queue->pdu, hdr->hlen);
                if (unlikely(ret))
                        return ret;
        }


        if (queue->data_digest) {
                ret = nvme_tcp_check_ddgst(queue, queue->pdu);
                if (unlikely(ret))
                        return ret;
        }

        switch (hdr->type) {
        case nvme_tcp_c2h_data:
                return nvme_tcp_handle_c2h_data(queue, (void *)queue->pdu);
        case nvme_tcp_rsp:
                nvme_tcp_init_recv_ctx(queue);
                return nvme_tcp_handle_comp(queue, (void *)queue->pdu);
        case nvme_tcp_r2t:
                nvme_tcp_init_recv_ctx(queue);
                return nvme_tcp_handle_r2t(queue, (void *)queue->pdu);
        default:
                dev_err(queue->ctrl->ctrl.device,
                        "unsupported pdu type (%d)\n", hdr->type);
                return -EINVAL;
        }
}

static inline void nvme_tcp_end_request(struct request *rq, u16 status)
{
        union nvme_result res = {};

        nvme_end_request(rq, cpu_to_le16(status << 1), res);
}

static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
                              unsigned int *offset, size_t *len)
{
        struct nvme_tcp_data_pdu *pdu = (void *)queue->pdu;
        struct nvme_tcp_request *req;
        struct request *rq;

        rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
        if (!rq) {
                dev_err(queue->ctrl->ctrl.device,
                        "queue %d tag %#x not found\n",
                        nvme_tcp_queue_id(queue), pdu->command_id);
                return -ENOENT;
        }
        req = blk_mq_rq_to_pdu(rq);

        while (true) {
                int recv_len, ret;

                recv_len = min_t(size_t, *len, queue->data_remaining);
                if (!recv_len)
                        break;

                if (!iov_iter_count(&req->iter)) {
                        req->curr_bio = req->curr_bio->bi_next;

                        /*
                         * If we don`t have any bios it means that controller
                         * sent more data than we requested, hence error
                         */
                        if (!req->curr_bio) {
                                dev_err(queue->ctrl->ctrl.device,
                                        "queue %d no space in request %#x",
                                        nvme_tcp_queue_id(queue), rq->tag);
                                nvme_tcp_init_recv_ctx(queue);
                                return -EIO;
                        }
                        nvme_tcp_init_iter(req, READ);
                }

                /* we can read only from what is left in this bio */
                recv_len = min_t(size_t, recv_len,
                                iov_iter_count(&req->iter));

                if (queue->data_digest)
                        ret = skb_copy_and_hash_datagram_iter(skb, *offset,
                                &req->iter, recv_len, queue->rcv_hash);
                else
                        ret = skb_copy_datagram_iter(skb, *offset,
                                        &req->iter, recv_len);
                if (ret) {
                        dev_err(queue->ctrl->ctrl.device,
                                "queue %d failed to copy request %#x data",
                                nvme_tcp_queue_id(queue), rq->tag);
                        return ret;
                }

                *len -= recv_len;
                *offset += recv_len;
                queue->data_remaining -= recv_len;
        }

        if (!queue->data_remaining) {
                if (queue->data_digest) {
                        nvme_tcp_ddgst_final(queue->rcv_hash, &queue->exp_ddgst);
                        queue->ddgst_remaining = NVME_TCP_DIGEST_LENGTH;
                } else {
                        if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
                                nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
                                queue->nr_cqe++;
                        }
                        nvme_tcp_init_recv_ctx(queue);
                }
        }

        return 0;
}

static int nvme_tcp_recv_ddgst(struct nvme_tcp_queue *queue,
                struct sk_buff *skb, unsigned int *offset, size_t *len)
{
        struct nvme_tcp_data_pdu *pdu = (void *)queue->pdu;
        char *ddgst = (char *)&queue->recv_ddgst;
        size_t recv_len = min_t(size_t, *len, queue->ddgst_remaining);
        off_t off = NVME_TCP_DIGEST_LENGTH - queue->ddgst_remaining;
        int ret;

        ret = skb_copy_bits(skb, *offset, &ddgst[off], recv_len);
        if (unlikely(ret))
                return ret;

        queue->ddgst_remaining -= recv_len;
        *offset += recv_len;
        *len -= recv_len;
        if (queue->ddgst_remaining)
                return 0;

        if (queue->recv_ddgst != queue->exp_ddgst) {
                dev_err(queue->ctrl->ctrl.device,
                        "data digest error: recv %#x expected %#x\n",
                        le32_to_cpu(queue->recv_ddgst),
                        le32_to_cpu(queue->exp_ddgst));
                return -EIO;
        }

        if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
                struct request *rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue),
                                                pdu->command_id);

                nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
                queue->nr_cqe++;
        }

        nvme_tcp_init_recv_ctx(queue);
        return 0;
}

static int nvme_tcp_recv_skb(read_descriptor_t *desc, struct sk_buff *skb,
                             unsigned int offset, size_t len)
{
        struct nvme_tcp_queue *queue = desc->arg.data;
        size_t consumed = len;
        int result;

        while (len) {
                switch (nvme_tcp_recv_state(queue)) {
                case NVME_TCP_RECV_PDU:
                        result = nvme_tcp_recv_pdu(queue, skb, &offset, &len);
                        break;
                case NVME_TCP_RECV_DATA:
                        result = nvme_tcp_recv_data(queue, skb, &offset, &len);
                        break;
                case NVME_TCP_RECV_DDGST:
                        result = nvme_tcp_recv_ddgst(queue, skb, &offset, &len);
                        break;
                default:
                        result = -EFAULT;
                }
                if (result) {
                        dev_err(queue->ctrl->ctrl.device,
                                "receive failed:  %d\n", result);
                        queue->rd_enabled = false;
                        nvme_tcp_error_recovery(&queue->ctrl->ctrl);
                        return result;
                }
        }

        return consumed;
}

static void nvme_tcp_data_ready(struct sock *sk)
{
        struct nvme_tcp_queue *queue;

        read_lock_bh(&sk->sk_callback_lock);
        queue = sk->sk_user_data;
        if (likely(queue && queue->rd_enabled) &&
            !test_bit(NVME_TCP_Q_POLLING, &queue->flags))
                queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
        read_unlock_bh(&sk->sk_callback_lock);
}

static void nvme_tcp_write_space(struct sock *sk)
{
        struct nvme_tcp_queue *queue;

        read_lock_bh(&sk->sk_callback_lock);
        queue = sk->sk_user_data;
        if (likely(queue && sk_stream_is_writeable(sk))) {
                clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
                queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
        }
        read_unlock_bh(&sk->sk_callback_lock);
}

static void nvme_tcp_state_change(struct sock *sk)
{
        struct nvme_tcp_queue *queue;

        read_lock(&sk->sk_callback_lock);
        queue = sk->sk_user_data;
        if (!queue)
                goto done;

        switch (sk->sk_state) {
        case TCP_CLOSE:
        case TCP_CLOSE_WAIT:
        case TCP_LAST_ACK:
        case TCP_FIN_WAIT1:
        case TCP_FIN_WAIT2:
                /* fallthrough */
                nvme_tcp_error_recovery(&queue->ctrl->ctrl);
                break;
        default:
                dev_info(queue->ctrl->ctrl.device,
                        "queue %d socket state %d\n",
                        nvme_tcp_queue_id(queue), sk->sk_state);
        }

        queue->state_change(sk);
done:
        read_unlock(&sk->sk_callback_lock);
}

static inline void nvme_tcp_done_send_req(struct nvme_tcp_queue *queue)
{
        queue->request = NULL;
}

static void nvme_tcp_fail_request(struct nvme_tcp_request *req)
{
        nvme_tcp_end_request(blk_mq_rq_from_pdu(req), NVME_SC_HOST_PATH_ERROR);
}

static int nvme_tcp_try_send_data(struct nvme_tcp_request *req)
{
        struct nvme_tcp_queue *queue = req->queue;

        while (true) {
                struct page *page = nvme_tcp_req_cur_page(req);
                size_t offset = nvme_tcp_req_cur_offset(req);
                size_t len = nvme_tcp_req_cur_length(req);
                bool last = nvme_tcp_pdu_last_send(req, len);
                int ret, flags = MSG_DONTWAIT;

                if (last && !queue->data_digest)
                        flags |= MSG_EOR;
                else
                        flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;

                /* can't zcopy slab pages */
                if (unlikely(PageSlab(page))) {
                        ret = sock_no_sendpage(queue->sock, page, offset, len,
                                        flags);
                } else {
                        ret = kernel_sendpage(queue->sock, page, offset, len,
                                        flags);
                }
                if (ret <= 0)
                        return ret;

                nvme_tcp_advance_req(req, ret);
                if (queue->data_digest)
                        nvme_tcp_ddgst_update(queue->snd_hash, page,
                                        offset, ret);

                /* fully successful last write*/
                if (last && ret == len) {
                        if (queue->data_digest) {
                                nvme_tcp_ddgst_final(queue->snd_hash,
                                        &req->ddgst);
                                req->state = NVME_TCP_SEND_DDGST;
                                req->offset = 0;
                        } else {
                                nvme_tcp_done_send_req(queue);
                        }
                        return 1;
                }
        }
        return -EAGAIN;
}

static int nvme_tcp_try_send_cmd_pdu(struct nvme_tcp_request *req)
{
        struct nvme_tcp_queue *queue = req->queue;
        struct nvme_tcp_cmd_pdu *pdu = req->pdu;
        bool inline_data = nvme_tcp_has_inline_data(req);
        u8 hdgst = nvme_tcp_hdgst_len(queue);
        int len = sizeof(*pdu) + hdgst - req->offset;
        int flags = MSG_DONTWAIT;
        int ret;

        if (inline_data)
                flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
        else
                flags |= MSG_EOR;

        if (queue->hdr_digest && !req->offset)
                nvme_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu));

        ret = kernel_sendpage(queue->sock, virt_to_page(pdu),
                        offset_in_page(pdu) + req->offset, len,  flags);
        if (unlikely(ret <= 0))
                return ret;

        len -= ret;
        if (!len) {
                if (inline_data) {
                        req->state = NVME_TCP_SEND_DATA;
                        if (queue->data_digest)
                                crypto_ahash_init(queue->snd_hash);
                        nvme_tcp_init_iter(req, WRITE);
                } else {
                        nvme_tcp_done_send_req(queue);
                }
                return 1;
        }
        req->offset += ret;

        return -EAGAIN;
}

static int nvme_tcp_try_send_data_pdu(struct nvme_tcp_request *req)
{
        struct nvme_tcp_queue *queue = req->queue;
        struct nvme_tcp_data_pdu *pdu = req->pdu;
        u8 hdgst = nvme_tcp_hdgst_len(queue);
        int len = sizeof(*pdu) - req->offset + hdgst;
        int ret;

        if (queue->hdr_digest && !req->offset)
                nvme_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu));

        ret = kernel_sendpage(queue->sock, virt_to_page(pdu),
                        offset_in_page(pdu) + req->offset, len,
                        MSG_DONTWAIT | MSG_MORE | MSG_SENDPAGE_NOTLAST);
        if (unlikely(ret <= 0))
                return ret;

        len -= ret;
        if (!len) {
                req->state = NVME_TCP_SEND_DATA;
                if (queue->data_digest)
                        crypto_ahash_init(queue->snd_hash);
                if (!req->data_sent)
                        nvme_tcp_init_iter(req, WRITE);
                return 1;
        }
        req->offset += ret;

        return -EAGAIN;
}

static int nvme_tcp_try_send_ddgst(struct nvme_tcp_request *req)
{
        struct nvme_tcp_queue *queue = req->queue;
        int ret;
        struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_EOR };
        struct kvec iov = {
                .iov_base = &req->ddgst + req->offset,
                .iov_len = NVME_TCP_DIGEST_LENGTH - req->offset

        };

        ret = kernel_sendmsg(queue->sock, &msg, &iov, 1, iov.iov_len);
        if (unlikely(ret <= 0))
                return ret;

        if (req->offset + ret == NVME_TCP_DIGEST_LENGTH) {
                nvme_tcp_done_send_req(queue);
                return 1;
        }

        req->offset += ret;
        return -EAGAIN;
}

static int nvme_tcp_try_send(struct nvme_tcp_queue *queue)
{
        struct nvme_tcp_request *req;
        int ret = 1;

        if (!queue->request) {
                queue->request = nvme_tcp_fetch_request(queue);
                if (!queue->request)
                        return 0;
        }
        req = queue->request;

        if (req->state == NVME_TCP_SEND_CMD_PDU) {
                ret = nvme_tcp_try_send_cmd_pdu(req);
                if (ret <= 0)
                        goto done;
                if (!nvme_tcp_has_inline_data(req))
                        return ret;
        }

        if (req->state == NVME_TCP_SEND_H2C_PDU) {
                ret = nvme_tcp_try_send_data_pdu(req);
                if (ret <= 0)
                        goto done;
        }

        if (req->state == NVME_TCP_SEND_DATA) {
                ret = nvme_tcp_try_send_data(req);
                if (ret <= 0)
                        goto done;
        }

        if (req->state == NVME_TCP_SEND_DDGST)
                ret = nvme_tcp_try_send_ddgst(req);
done:
        if (ret == -EAGAIN) {
                ret = 0;
        } else if (ret < 0) {
                dev_err(queue->ctrl->ctrl.device,
                        "failed to send request %d\n", ret);
                if (ret != -EPIPE && ret != -ECONNRESET)
                        nvme_tcp_fail_request(queue->request);
                nvme_tcp_done_send_req(queue);
        }
        return ret;
}

static int nvme_tcp_try_recv(struct nvme_tcp_queue *queue)
{
        struct socket *sock = queue->sock;
        struct sock *sk = sock->sk;
        read_descriptor_t rd_desc;
        int consumed;

        rd_desc.arg.data = queue;
        rd_desc.count = 1;
        lock_sock(sk);
        queue->nr_cqe = 0;
        consumed = sock->ops->read_sock(sk, &rd_desc, nvme_tcp_recv_skb);
        release_sock(sk);
        return consumed;
}

static void nvme_tcp_io_work(struct work_struct *w)
{
        struct nvme_tcp_queue *queue =
                container_of(w, struct nvme_tcp_queue, io_work);
        unsigned long deadline = jiffies + msecs_to_jiffies(1);

        do {
                bool pending = false;
                int result;

                if (mutex_trylock(&queue->send_mutex)) {
                        result = nvme_tcp_try_send(queue);
                        mutex_unlock(&queue->send_mutex);
                        if (result > 0)
                                pending = true;
                        else if (unlikely(result < 0))
                                break;
                }

                result = nvme_tcp_try_recv(queue);
                if (result > 0)
                        pending = true;
                else if (unlikely(result < 0))
                        return;

                if (!pending)
                        return;

        } while (!time_after(jiffies, deadline)); /* quota is exhausted */

        queue_work_on(queue->io_cpu, nvme_tcp_wq, &queue->io_work);
}

static void nvme_tcp_free_crypto(struct nvme_tcp_queue *queue)
{
        struct crypto_ahash *tfm = crypto_ahash_reqtfm(queue->rcv_hash);

        ahash_request_free(queue->rcv_hash);
        ahash_request_free(queue->snd_hash);
        crypto_free_ahash(tfm);
}

static int nvme_tcp_alloc_crypto(struct nvme_tcp_queue *queue)
{
        struct crypto_ahash *tfm;

        tfm = crypto_alloc_ahash("crc32c", 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(tfm))
                return PTR_ERR(tfm);

        queue->snd_hash = ahash_request_alloc(tfm, GFP_KERNEL);
        if (!queue->snd_hash)
                goto free_tfm;
        ahash_request_set_callback(queue->snd_hash, 0, NULL, NULL);

        queue->rcv_hash = ahash_request_alloc(tfm, GFP_KERNEL);
        if (!queue->rcv_hash)
                goto free_snd_hash;
        ahash_request_set_callback(queue->rcv_hash, 0, NULL, NULL);

        return 0;
free_snd_hash:
        ahash_request_free(queue->snd_hash);
free_tfm:
        crypto_free_ahash(tfm);
        return -ENOMEM;
}

static void nvme_tcp_free_async_req(struct nvme_tcp_ctrl *ctrl)
{
        struct nvme_tcp_request *async = &ctrl->async_req;

        page_frag_free(async->pdu);
}

static int nvme_tcp_alloc_async_req(struct nvme_tcp_ctrl *ctrl)
{
        struct nvme_tcp_queue *queue = &ctrl->queues[0];
        struct nvme_tcp_request *async = &ctrl->async_req;
        u8 hdgst = nvme_tcp_hdgst_len(queue);

        async->pdu = page_frag_alloc(&queue->pf_cache,
                sizeof(struct nvme_tcp_cmd_pdu) + hdgst,
                GFP_KERNEL | __GFP_ZERO);
        if (!async->pdu)
                return -ENOMEM;

        async->queue = &ctrl->queues[0];
        return 0;
}

static void nvme_tcp_free_queue(struct nvme_ctrl *nctrl, int qid)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
        struct nvme_tcp_queue *queue = &ctrl->queues[qid];

        if (!test_and_clear_bit(NVME_TCP_Q_ALLOCATED, &queue->flags))
                return;

        if (queue->hdr_digest || queue->data_digest)
                nvme_tcp_free_crypto(queue);

        sock_release(queue->sock);
        kfree(queue->pdu);
}

static int nvme_tcp_init_connection(struct nvme_tcp_queue *queue)
{
        struct nvme_tcp_icreq_pdu *icreq;
        struct nvme_tcp_icresp_pdu *icresp;
        struct msghdr msg = {};
        struct kvec iov;
        bool ctrl_hdgst, ctrl_ddgst;
        int ret;

        icreq = kzalloc(sizeof(*icreq), GFP_KERNEL);
        if (!icreq)
                return -ENOMEM;

        icresp = kzalloc(sizeof(*icresp), GFP_KERNEL);
        if (!icresp) {
                ret = -ENOMEM;
                goto free_icreq;
        }

        icreq->hdr.type = nvme_tcp_icreq;
        icreq->hdr.hlen = sizeof(*icreq);
        icreq->hdr.pdo = 0;
        icreq->hdr.plen = cpu_to_le32(icreq->hdr.hlen);
        icreq->pfv = cpu_to_le16(NVME_TCP_PFV_1_0);
        icreq->maxr2t = 0; /* single inflight r2t supported */
        icreq->hpda = 0; /* no alignment constraint */
        if (queue->hdr_digest)
                icreq->digest |= NVME_TCP_HDR_DIGEST_ENABLE;
        if (queue->data_digest)
                icreq->digest |= NVME_TCP_DATA_DIGEST_ENABLE;

        iov.iov_base = icreq;
        iov.iov_len = sizeof(*icreq);
        ret = kernel_sendmsg(queue->sock, &msg, &iov, 1, iov.iov_len);
        if (ret < 0)
                goto free_icresp;

        memset(&msg, 0, sizeof(msg));
        iov.iov_base = icresp;
        iov.iov_len = sizeof(*icresp);
        ret = kernel_recvmsg(queue->sock, &msg, &iov, 1,
                        iov.iov_len, msg.msg_flags);
        if (ret < 0)
                goto free_icresp;

        ret = -EINVAL;
        if (icresp->hdr.type != nvme_tcp_icresp) {
                pr_err("queue %d: bad type returned %d\n",
                        nvme_tcp_queue_id(queue), icresp->hdr.type);
                goto free_icresp;
        }

        if (le32_to_cpu(icresp->hdr.plen) != sizeof(*icresp)) {
                pr_err("queue %d: bad pdu length returned %d\n",
                        nvme_tcp_queue_id(queue), icresp->hdr.plen);
                goto free_icresp;
        }

        if (icresp->pfv != NVME_TCP_PFV_1_0) {
                pr_err("queue %d: bad pfv returned %d\n",
                        nvme_tcp_queue_id(queue), icresp->pfv);
                goto free_icresp;
        }

        ctrl_ddgst = !!(icresp->digest & NVME_TCP_DATA_DIGEST_ENABLE);
        if ((queue->data_digest && !ctrl_ddgst) ||
            (!queue->data_digest && ctrl_ddgst)) {
                pr_err("queue %d: data digest mismatch host: %s ctrl: %s\n",
                        nvme_tcp_queue_id(queue),
                        queue->data_digest ? "enabled" : "disabled",
                        ctrl_ddgst ? "enabled" : "disabled");
                goto free_icresp;
        }

        ctrl_hdgst = !!(icresp->digest & NVME_TCP_HDR_DIGEST_ENABLE);
        if ((queue->hdr_digest && !ctrl_hdgst) ||
            (!queue->hdr_digest && ctrl_hdgst)) {
                pr_err("queue %d: header digest mismatch host: %s ctrl: %s\n",
                        nvme_tcp_queue_id(queue),
                        queue->hdr_digest ? "enabled" : "disabled",
                        ctrl_hdgst ? "enabled" : "disabled");
                goto free_icresp;
        }

        if (icresp->cpda != 0) {
                pr_err("queue %d: unsupported cpda returned %d\n",
                        nvme_tcp_queue_id(queue), icresp->cpda);
                goto free_icresp;
        }

        ret = 0;
free_icresp:
        kfree(icresp);
free_icreq:
        kfree(icreq);
        return ret;
}

static bool nvme_tcp_admin_queue(struct nvme_tcp_queue *queue)
{
        return nvme_tcp_queue_id(queue) == 0;
}

static bool nvme_tcp_default_queue(struct nvme_tcp_queue *queue)
{
        struct nvme_tcp_ctrl *ctrl = queue->ctrl;
        int qid = nvme_tcp_queue_id(queue);

        return !nvme_tcp_admin_queue(queue) &&
                qid < 1 + ctrl->io_queues[HCTX_TYPE_DEFAULT];
}

static bool nvme_tcp_read_queue(struct nvme_tcp_queue *queue)
{
        struct nvme_tcp_ctrl *ctrl = queue->ctrl;
        int qid = nvme_tcp_queue_id(queue);

        return !nvme_tcp_admin_queue(queue) &&
                !nvme_tcp_default_queue(queue) &&
                qid < 1 + ctrl->io_queues[HCTX_TYPE_DEFAULT] +
                          ctrl->io_queues[HCTX_TYPE_READ];
}

static bool nvme_tcp_poll_queue(struct nvme_tcp_queue *queue)
{
        struct nvme_tcp_ctrl *ctrl = queue->ctrl;
        int qid = nvme_tcp_queue_id(queue);

        return !nvme_tcp_admin_queue(queue) &&
                !nvme_tcp_default_queue(queue) &&
                !nvme_tcp_read_queue(queue) &&
                qid < 1 + ctrl->io_queues[HCTX_TYPE_DEFAULT] +
                          ctrl->io_queues[HCTX_TYPE_READ] +
                          ctrl->io_queues[HCTX_TYPE_POLL];
}

static void nvme_tcp_set_queue_io_cpu(struct nvme_tcp_queue *queue)
{
        struct nvme_tcp_ctrl *ctrl = queue->ctrl;
        int qid = nvme_tcp_queue_id(queue);
        int n = 0;

        if (nvme_tcp_default_queue(queue))
                n = qid - 1;
        else if (nvme_tcp_read_queue(queue))
                n = qid - ctrl->io_queues[HCTX_TYPE_DEFAULT] - 1;
        else if (nvme_tcp_poll_queue(queue))
                n = qid - ctrl->io_queues[HCTX_TYPE_DEFAULT] -
                                ctrl->io_queues[HCTX_TYPE_READ] - 1;
        queue->io_cpu = cpumask_next_wrap(n - 1, cpu_online_mask, -1, false);
}

static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
                int qid, size_t queue_size)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
        struct nvme_tcp_queue *queue = &ctrl->queues[qid];
        int ret, rcv_pdu_size;

        queue->ctrl = ctrl;
        INIT_LIST_HEAD(&queue->send_list);
        spin_lock_init(&queue->lock);
        mutex_init(&queue->send_mutex);
        INIT_WORK(&queue->io_work, nvme_tcp_io_work);
        queue->queue_size = queue_size;

        if (qid > 0)
                queue->cmnd_capsule_len = nctrl->ioccsz * 16;
        else
                queue->cmnd_capsule_len = sizeof(struct nvme_command) +
                                                NVME_TCP_ADMIN_CCSZ;

        ret = sock_create(ctrl->addr.ss_family, SOCK_STREAM,
                        IPPROTO_TCP, &queue->sock);
        if (ret) {
                dev_err(nctrl->device,
                        "failed to create socket: %d\n", ret);
                return ret;
        }

        /* Single syn retry */
        tcp_sock_set_syncnt(queue->sock->sk, 1);

        /* Set TCP no delay */
        tcp_sock_set_nodelay(queue->sock->sk);

        /*
         * Cleanup whatever is sitting in the TCP transmit queue on socket
         * close. This is done to prevent stale data from being sent should
         * the network connection be restored before TCP times out.
         */
        sock_no_linger(queue->sock->sk);

        if (so_priority > 0)
                sock_set_priority(queue->sock->sk, so_priority);

        /* Set socket type of service */
        if (nctrl->opts->tos >= 0)
                ip_sock_set_tos(queue->sock->sk, nctrl->opts->tos);

        /* Set 10 seconds timeout for icresp recvmsg */
        queue->sock->sk->sk_rcvtimeo = 10 * HZ;

        queue->sock->sk->sk_allocation = GFP_ATOMIC;
        nvme_tcp_set_queue_io_cpu(queue);
        queue->request = NULL;
        queue->data_remaining = 0;
        queue->ddgst_remaining = 0;
        queue->pdu_remaining = 0;
        queue->pdu_offset = 0;
        sk_set_memalloc(queue->sock->sk);

        if (nctrl->opts->mask & NVMF_OPT_HOST_TRADDR) {
                ret = kernel_bind(queue->sock, (struct sockaddr *)&ctrl->src_addr,
                        sizeof(ctrl->src_addr));
                if (ret) {
                        dev_err(nctrl->device,
                                "failed to bind queue %d socket %d\n",
                                qid, ret);
                        goto err_sock;
                }
        }

        queue->hdr_digest = nctrl->opts->hdr_digest;
        queue->data_digest = nctrl->opts->data_digest;
        if (queue->hdr_digest || queue->data_digest) {
                ret = nvme_tcp_alloc_crypto(queue);
                if (ret) {
                        dev_err(nctrl->device,
                                "failed to allocate queue %d crypto\n", qid);
                        goto err_sock;
                }
        }

        rcv_pdu_size = sizeof(struct nvme_tcp_rsp_pdu) +
                        nvme_tcp_hdgst_len(queue);
        queue->pdu = kmalloc(rcv_pdu_size, GFP_KERNEL);
        if (!queue->pdu) {
                ret = -ENOMEM;
                goto err_crypto;
        }

        dev_dbg(nctrl->device, "connecting queue %d\n",
                        nvme_tcp_queue_id(queue));

        ret = kernel_connect(queue->sock, (struct sockaddr *)&ctrl->addr,
                sizeof(ctrl->addr), 0);
        if (ret) {
                dev_err(nctrl->device,
                        "failed to connect socket: %d\n", ret);
                goto err_rcv_pdu;
        }

        ret = nvme_tcp_init_connection(queue);
        if (ret)
                goto err_init_connect;

        queue->rd_enabled = true;
        set_bit(NVME_TCP_Q_ALLOCATED, &queue->flags);
        nvme_tcp_init_recv_ctx(queue);

        write_lock_bh(&queue->sock->sk->sk_callback_lock);
        queue->sock->sk->sk_user_data = queue;
        queue->state_change = queue->sock->sk->sk_state_change;
        queue->data_ready = queue->sock->sk->sk_data_ready;
        queue->write_space = queue->sock->sk->sk_write_space;
        queue->sock->sk->sk_data_ready = nvme_tcp_data_ready;
        queue->sock->sk->sk_state_change = nvme_tcp_state_change;
        queue->sock->sk->sk_write_space = nvme_tcp_write_space;
#ifdef CONFIG_NET_RX_BUSY_POLL
        queue->sock->sk->sk_ll_usec = 1;
#endif
        write_unlock_bh(&queue->sock->sk->sk_callback_lock);

        return 0;

err_init_connect:
        kernel_sock_shutdown(queue->sock, SHUT_RDWR);
err_rcv_pdu:
        kfree(queue->pdu);
err_crypto:
        if (queue->hdr_digest || queue->data_digest)
                nvme_tcp_free_crypto(queue);
err_sock:
        sock_release(queue->sock);
        queue->sock = NULL;
        return ret;
}

static void nvme_tcp_restore_sock_calls(struct nvme_tcp_queue *queue)
{
        struct socket *sock = queue->sock;

        write_lock_bh(&sock->sk->sk_callback_lock);
        sock->sk->sk_user_data  = NULL;
        sock->sk->sk_data_ready = queue->data_ready;
        sock->sk->sk_state_change = queue->state_change;
        sock->sk->sk_write_space  = queue->write_space;
        write_unlock_bh(&sock->sk->sk_callback_lock);
}

static void __nvme_tcp_stop_queue(struct nvme_tcp_queue *queue)
{
        kernel_sock_shutdown(queue->sock, SHUT_RDWR);
        nvme_tcp_restore_sock_calls(queue);
        cancel_work_sync(&queue->io_work);
}

static void nvme_tcp_stop_queue(struct nvme_ctrl *nctrl, int qid)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
        struct nvme_tcp_queue *queue = &ctrl->queues[qid];

        if (!test_and_clear_bit(NVME_TCP_Q_LIVE, &queue->flags))
                return;

        __nvme_tcp_stop_queue(queue);
}

static int nvme_tcp_start_queue(struct nvme_ctrl *nctrl, int idx)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
        int ret;

        if (idx)
                ret = nvmf_connect_io_queue(nctrl, idx, false);
        else
                ret = nvmf_connect_admin_queue(nctrl);

        if (!ret) {
                set_bit(NVME_TCP_Q_LIVE, &ctrl->queues[idx].flags);
        } else {
                if (test_bit(NVME_TCP_Q_ALLOCATED, &ctrl->queues[idx].flags))
                        __nvme_tcp_stop_queue(&ctrl->queues[idx]);
                dev_err(nctrl->device,
                        "failed to connect queue: %d ret=%d\n", idx, ret);
        }
        return ret;
}

static struct blk_mq_tag_set *nvme_tcp_alloc_tagset(struct nvme_ctrl *nctrl,
                bool admin)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
        struct blk_mq_tag_set *set;
        int ret;

        if (admin) {
                set = &ctrl->admin_tag_set;
                memset(set, 0, sizeof(*set));
                set->ops = &nvme_tcp_admin_mq_ops;
                set->queue_depth = NVME_AQ_MQ_TAG_DEPTH;
                set->reserved_tags = 2; /* connect + keep-alive */
                set->numa_node = nctrl->numa_node;
                set->flags = BLK_MQ_F_BLOCKING;
                set->cmd_size = sizeof(struct nvme_tcp_request);
                set->driver_data = ctrl;
                set->nr_hw_queues = 1;
                set->timeout = ADMIN_TIMEOUT;
        } else {
                set = &ctrl->tag_set;
                memset(set, 0, sizeof(*set));
                set->ops = &nvme_tcp_mq_ops;
                set->queue_depth = nctrl->sqsize + 1;
                set->reserved_tags = 1; /* fabric connect */
                set->numa_node = nctrl->numa_node;
                set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING;
                set->cmd_size = sizeof(struct nvme_tcp_request);
                set->driver_data = ctrl;
                set->nr_hw_queues = nctrl->queue_count - 1;
                set->timeout = NVME_IO_TIMEOUT;
                set->nr_maps = nctrl->opts->nr_poll_queues ? HCTX_MAX_TYPES : 2;
        }

        ret = blk_mq_alloc_tag_set(set);
        if (ret)
                return ERR_PTR(ret);

        return set;
}

static void nvme_tcp_free_admin_queue(struct nvme_ctrl *ctrl)
{
        if (to_tcp_ctrl(ctrl)->async_req.pdu) {
                nvme_tcp_free_async_req(to_tcp_ctrl(ctrl));
                to_tcp_ctrl(ctrl)->async_req.pdu = NULL;
        }

        nvme_tcp_free_queue(ctrl, 0);
}

static void nvme_tcp_free_io_queues(struct nvme_ctrl *ctrl)
{
        int i;

        for (i = 1; i < ctrl->queue_count; i++)
                nvme_tcp_free_queue(ctrl, i);
}

static void nvme_tcp_stop_io_queues(struct nvme_ctrl *ctrl)
{
        int i;

        for (i = 1; i < ctrl->queue_count; i++)
                nvme_tcp_stop_queue(ctrl, i);
}

static int nvme_tcp_start_io_queues(struct nvme_ctrl *ctrl)
{
        int i, ret = 0;

        for (i = 1; i < ctrl->queue_count; i++) {
                ret = nvme_tcp_start_queue(ctrl, i);
                if (ret)
                        goto out_stop_queues;
        }

        return 0;

out_stop_queues:
        for (i--; i >= 1; i--)
                nvme_tcp_stop_queue(ctrl, i);
        return ret;
}

static int nvme_tcp_alloc_admin_queue(struct nvme_ctrl *ctrl)
{
        int ret;

        ret = nvme_tcp_alloc_queue(ctrl, 0, NVME_AQ_DEPTH);
        if (ret)
                return ret;

        ret = nvme_tcp_alloc_async_req(to_tcp_ctrl(ctrl));
        if (ret)
                goto out_free_queue;

        return 0;

out_free_queue:
        nvme_tcp_free_queue(ctrl, 0);
        return ret;
}

static int __nvme_tcp_alloc_io_queues(struct nvme_ctrl *ctrl)
{
        int i, ret;

        for (i = 1; i < ctrl->queue_count; i++) {
                ret = nvme_tcp_alloc_queue(ctrl, i,
                                ctrl->sqsize + 1);
                if (ret)
                        goto out_free_queues;
        }

        return 0;

out_free_queues:
        for (i--; i >= 1; i--)
                nvme_tcp_free_queue(ctrl, i);

        return ret;
}

static unsigned int nvme_tcp_nr_io_queues(struct nvme_ctrl *ctrl)
{
        unsigned int nr_io_queues;

        nr_io_queues = min(ctrl->opts->nr_io_queues, num_online_cpus());
        nr_io_queues += min(ctrl->opts->nr_write_queues, num_online_cpus());
        nr_io_queues += min(ctrl->opts->nr_poll_queues, num_online_cpus());

        return nr_io_queues;
}

static void nvme_tcp_set_io_queues(struct nvme_ctrl *nctrl,
                unsigned int nr_io_queues)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
        struct nvmf_ctrl_options *opts = nctrl->opts;

        if (opts->nr_write_queues && opts->nr_io_queues < nr_io_queues) {
                /*
                 * separate read/write queues
                 * hand out dedicated default queues only after we have
                 * sufficient read queues.
                 */
                ctrl->io_queues[HCTX_TYPE_READ] = opts->nr_io_queues;
                nr_io_queues -= ctrl->io_queues[HCTX_TYPE_READ];
                ctrl->io_queues[HCTX_TYPE_DEFAULT] =
                        min(opts->nr_write_queues, nr_io_queues);
                nr_io_queues -= ctrl->io_queues[HCTX_TYPE_DEFAULT];
        } else {
                /*
                 * shared read/write queues
                 * either no write queues were requested, or we don't have
                 * sufficient queue count to have dedicated default queues.
                 */
                ctrl->io_queues[HCTX_TYPE_DEFAULT] =
                        min(opts->nr_io_queues, nr_io_queues);
                nr_io_queues -= ctrl->io_queues[HCTX_TYPE_DEFAULT];
        }

        if (opts->nr_poll_queues && nr_io_queues) {
                /* map dedicated poll queues only if we have queues left */
                ctrl->io_queues[HCTX_TYPE_POLL] =
                        min(opts->nr_poll_queues, nr_io_queues);
        }
}

static int nvme_tcp_alloc_io_queues(struct nvme_ctrl *ctrl)
{
        unsigned int nr_io_queues;
        int ret;

        nr_io_queues = nvme_tcp_nr_io_queues(ctrl);
        ret = nvme_set_queue_count(ctrl, &nr_io_queues);
        if (ret)
                return ret;

        ctrl->queue_count = nr_io_queues + 1;
        if (ctrl->queue_count < 2)
                return 0;

        dev_info(ctrl->device,
                "creating %d I/O queues.\n", nr_io_queues);

        nvme_tcp_set_io_queues(ctrl, nr_io_queues);

        return __nvme_tcp_alloc_io_queues(ctrl);
}

static void nvme_tcp_destroy_io_queues(struct nvme_ctrl *ctrl, bool remove)
{
        nvme_tcp_stop_io_queues(ctrl);
        if (remove) {
                blk_cleanup_queue(ctrl->connect_q);
                blk_mq_free_tag_set(ctrl->tagset);
        }
        nvme_tcp_free_io_queues(ctrl);
}

static int nvme_tcp_configure_io_queues(struct nvme_ctrl *ctrl, bool new)
{
        int ret;

        ret = nvme_tcp_alloc_io_queues(ctrl);
        if (ret)
                return ret;

        if (new) {
                ctrl->tagset = nvme_tcp_alloc_tagset(ctrl, false);
                if (IS_ERR(ctrl->tagset)) {
                        ret = PTR_ERR(ctrl->tagset);
                        goto out_free_io_queues;
                }

                ctrl->connect_q = blk_mq_init_queue(ctrl->tagset);
                if (IS_ERR(ctrl->connect_q)) {
                        ret = PTR_ERR(ctrl->connect_q);
                        goto out_free_tag_set;
                }
        } else {
                blk_mq_update_nr_hw_queues(ctrl->tagset,
                        ctrl->queue_count - 1);
        }

        ret = nvme_tcp_start_io_queues(ctrl);
        if (ret)
                goto out_cleanup_connect_q;

        return 0;

out_cleanup_connect_q:
        if (new)
                blk_cleanup_queue(ctrl->connect_q);
out_free_tag_set:
        if (new)
                blk_mq_free_tag_set(ctrl->tagset);
out_free_io_queues:
        nvme_tcp_free_io_queues(ctrl);
        return ret;
}

static void nvme_tcp_destroy_admin_queue(struct nvme_ctrl *ctrl, bool remove)
{
        nvme_tcp_stop_queue(ctrl, 0);
        if (remove) {
                blk_cleanup_queue(ctrl->admin_q);
                blk_cleanup_queue(ctrl->fabrics_q);
                blk_mq_free_tag_set(ctrl->admin_tagset);
        }
        nvme_tcp_free_admin_queue(ctrl);
}

static int nvme_tcp_configure_admin_queue(struct nvme_ctrl *ctrl, bool new)
{
        int error;

        error = nvme_tcp_alloc_admin_queue(ctrl);
        if (error)
                return error;

        if (new) {
                ctrl->admin_tagset = nvme_tcp_alloc_tagset(ctrl, true);
                if (IS_ERR(ctrl->admin_tagset)) {
                        error = PTR_ERR(ctrl->admin_tagset);
                        goto out_free_queue;
                }

                ctrl->fabrics_q = blk_mq_init_queue(ctrl->admin_tagset);
                if (IS_ERR(ctrl->fabrics_q)) {
                        error = PTR_ERR(ctrl->fabrics_q);
                        goto out_free_tagset;
                }

                ctrl->admin_q = blk_mq_init_queue(ctrl->admin_tagset);
                if (IS_ERR(ctrl->admin_q)) {
                        error = PTR_ERR(ctrl->admin_q);
                        goto out_cleanup_fabrics_q;
                }
        }

        error = nvme_tcp_start_queue(ctrl, 0);
        if (error)
                goto out_cleanup_queue;

        error = nvme_enable_ctrl(ctrl);
        if (error)
                goto out_stop_queue;

        blk_mq_unquiesce_queue(ctrl->admin_q);

        error = nvme_init_identify(ctrl);
        if (error)
                goto out_stop_queue;

        return 0;

out_stop_queue:
        nvme_tcp_stop_queue(ctrl, 0);
out_cleanup_queue:
        if (new)
                blk_cleanup_queue(ctrl->admin_q);
out_cleanup_fabrics_q:
        if (new)
                blk_cleanup_queue(ctrl->fabrics_q);
out_free_tagset:
        if (new)
                blk_mq_free_tag_set(ctrl->admin_tagset);
out_free_queue:
        nvme_tcp_free_admin_queue(ctrl);
        return error;
}

static void nvme_tcp_teardown_admin_queue(struct nvme_ctrl *ctrl,
                bool remove)
{
        blk_mq_quiesce_queue(ctrl->admin_q);
        nvme_tcp_stop_queue(ctrl, 0);
        if (ctrl->admin_tagset) {
                blk_mq_tagset_busy_iter(ctrl->admin_tagset,
                        nvme_cancel_request, ctrl);
                blk_mq_tagset_wait_completed_request(ctrl->admin_tagset);
        }
        if (remove)
                blk_mq_unquiesce_queue(ctrl->admin_q);
        nvme_tcp_destroy_admin_queue(ctrl, remove);
}

static void nvme_tcp_teardown_io_queues(struct nvme_ctrl *ctrl,
                bool remove)
{
        if (ctrl->queue_count <= 1)
                return;
        nvme_stop_queues(ctrl);
        nvme_tcp_stop_io_queues(ctrl);
        if (ctrl->tagset) {
                blk_mq_tagset_busy_iter(ctrl->tagset,
                        nvme_cancel_request, ctrl);
                blk_mq_tagset_wait_completed_request(ctrl->tagset);
        }
        if (remove)
                nvme_start_queues(ctrl);
        nvme_tcp_destroy_io_queues(ctrl, remove);
}

static void nvme_tcp_reconnect_or_remove(struct nvme_ctrl *ctrl)
{
        /* If we are resetting/deleting then do nothing */
        if (ctrl->state != NVME_CTRL_CONNECTING) {
                WARN_ON_ONCE(ctrl->state == NVME_CTRL_NEW ||
                        ctrl->state == NVME_CTRL_LIVE);
                return;
        }

        if (nvmf_should_reconnect(ctrl)) {
                dev_info(ctrl->device, "Reconnecting in %d seconds...\n",
                        ctrl->opts->reconnect_delay);
                queue_delayed_work(nvme_wq, &to_tcp_ctrl(ctrl)->connect_work,
                                ctrl->opts->reconnect_delay * HZ);
        } else {
                dev_info(ctrl->device, "Removing controller...\n");
                nvme_delete_ctrl(ctrl);
        }
}

static int nvme_tcp_setup_ctrl(struct nvme_ctrl *ctrl, bool new)
{
        struct nvmf_ctrl_options *opts = ctrl->opts;
        int ret;

        ret = nvme_tcp_configure_admin_queue(ctrl, new);
        if (ret)
                return ret;

        if (ctrl->icdoff) {
                dev_err(ctrl->device, "icdoff is not supported!\n");
                goto destroy_admin;
        }

        if (opts->queue_size > ctrl->sqsize + 1)
                dev_warn(ctrl->device,
                        "queue_size %zu > ctrl sqsize %u, clamping down\n",
                        opts->queue_size, ctrl->sqsize + 1);

        if (ctrl->sqsize + 1 > ctrl->maxcmd) {
                dev_warn(ctrl->device,
                        "sqsize %u > ctrl maxcmd %u, clamping down\n",
                        ctrl->sqsize + 1, ctrl->maxcmd);
                ctrl->sqsize = ctrl->maxcmd - 1;
        }

        if (ctrl->queue_count > 1) {
                ret = nvme_tcp_configure_io_queues(ctrl, new);
                if (ret)
                        goto destroy_admin;
        }

        if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE)) {
                /*
                 * state change failure is ok if we're in DELETING state,
                 * unless we're during creation of a new controller to
                 * avoid races with teardown flow.
                 */
                WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING);
                WARN_ON_ONCE(new);
                ret = -EINVAL;
                goto destroy_io;
        }

        nvme_start_ctrl(ctrl);
        return 0;

destroy_io:
        if (ctrl->queue_count > 1)
                nvme_tcp_destroy_io_queues(ctrl, new);
destroy_admin:
        nvme_tcp_stop_queue(ctrl, 0);
        nvme_tcp_destroy_admin_queue(ctrl, new);
        return ret;
}

static void nvme_tcp_reconnect_ctrl_work(struct work_struct *work)
{
        struct nvme_tcp_ctrl *tcp_ctrl = container_of(to_delayed_work(work),
                        struct nvme_tcp_ctrl, connect_work);
        struct nvme_ctrl *ctrl = &tcp_ctrl->ctrl;

        ++ctrl->nr_reconnects;

        if (nvme_tcp_setup_ctrl(ctrl, false))
                goto requeue;

        dev_info(ctrl->device, "Successfully reconnected (%d attempt)\n",
                        ctrl->nr_reconnects);

        ctrl->nr_reconnects = 0;

        return;

requeue:
        dev_info(ctrl->device, "Failed reconnect attempt %d\n",
                        ctrl->nr_reconnects);
        nvme_tcp_reconnect_or_remove(ctrl);
}

static void nvme_tcp_error_recovery_work(struct work_struct *work)
{
        struct nvme_tcp_ctrl *tcp_ctrl = container_of(work,
                                struct nvme_tcp_ctrl, err_work);
        struct nvme_ctrl *ctrl = &tcp_ctrl->ctrl;

        nvme_stop_keep_alive(ctrl);
        nvme_tcp_teardown_io_queues(ctrl, false);
        /* unquiesce to fail fast pending requests */
        nvme_start_queues(ctrl);
        nvme_tcp_teardown_admin_queue(ctrl, false);
        blk_mq_unquiesce_queue(ctrl->admin_q);

        if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_CONNECTING)) {
                /* state change failure is ok if we're in DELETING state */
                WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING);
                return;
        }

        nvme_tcp_reconnect_or_remove(ctrl);
}

static void nvme_tcp_teardown_ctrl(struct nvme_ctrl *ctrl, bool shutdown)
{
        cancel_work_sync(&to_tcp_ctrl(ctrl)->err_work);
        cancel_delayed_work_sync(&to_tcp_ctrl(ctrl)->connect_work);

        nvme_tcp_teardown_io_queues(ctrl, shutdown);
        blk_mq_quiesce_queue(ctrl->admin_q);

        if (shutdown)
                nvme_shutdown_ctrl(ctrl);
        else
                nvme_disable_ctrl(ctrl);
        nvme_tcp_teardown_admin_queue(ctrl, shutdown);
}

static void nvme_tcp_delete_ctrl(struct nvme_ctrl *ctrl)
{
        nvme_tcp_teardown_ctrl(ctrl, true);
}

static void nvme_reset_ctrl_work(struct work_struct *work)
{
        struct nvme_ctrl *ctrl =
                container_of(work, struct nvme_ctrl, reset_work);

        nvme_stop_ctrl(ctrl);
        nvme_tcp_teardown_ctrl(ctrl, false);

        if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_CONNECTING)) {
                /* state change failure is ok if we're in DELETING state */
                WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING);
                return;
        }

        if (nvme_tcp_setup_ctrl(ctrl, false))
                goto out_fail;

        return;

out_fail:
        ++ctrl->nr_reconnects;
        nvme_tcp_reconnect_or_remove(ctrl);
}

static void nvme_tcp_free_ctrl(struct nvme_ctrl *nctrl)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);

        if (list_empty(&ctrl->list))
                goto free_ctrl;

        mutex_lock(&nvme_tcp_ctrl_mutex);
        list_del(&ctrl->list);
        mutex_unlock(&nvme_tcp_ctrl_mutex);

        nvmf_free_options(nctrl->opts);
free_ctrl:
        kfree(ctrl->queues);
        kfree(ctrl);
}

static void nvme_tcp_set_sg_null(struct nvme_command *c)
{
        struct nvme_sgl_desc *sg = &c->common.dptr.sgl;

        sg->addr = 0;
        sg->length = 0;
        sg->type = (NVME_TRANSPORT_SGL_DATA_DESC << 4) |
                        NVME_SGL_FMT_TRANSPORT_A;
}

static void nvme_tcp_set_sg_inline(struct nvme_tcp_queue *queue,
                struct nvme_command *c, u32 data_len)
{
        struct nvme_sgl_desc *sg = &c->common.dptr.sgl;

        sg->addr = cpu_to_le64(queue->ctrl->ctrl.icdoff);
        sg->length = cpu_to_le32(data_len);
        sg->type = (NVME_SGL_FMT_DATA_DESC << 4) | NVME_SGL_FMT_OFFSET;
}

static void nvme_tcp_set_sg_host_data(struct nvme_command *c,
                u32 data_len)
{
        struct nvme_sgl_desc *sg = &c->common.dptr.sgl;

        sg->addr = 0;
        sg->length = cpu_to_le32(data_len);
        sg->type = (NVME_TRANSPORT_SGL_DATA_DESC << 4) |
                        NVME_SGL_FMT_TRANSPORT_A;
}

static void nvme_tcp_submit_async_event(struct nvme_ctrl *arg)
{
        struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(arg);
        struct nvme_tcp_queue *queue = &ctrl->queues[0];
        struct nvme_tcp_cmd_pdu *pdu = ctrl->async_req.pdu;
        struct nvme_command *cmd = &pdu->cmd;
        u8 hdgst = nvme_tcp_hdgst_len(queue);

        memset(pdu, 0, sizeof(*pdu));
        pdu->hdr.type = nvme_tcp_cmd;
        if (queue->hdr_digest)
                pdu->hdr.flags |= NVME_TCP_F_HDGST;
        pdu->hdr.hlen = sizeof(*pdu);
        pdu->hdr.plen = cpu_to_le32(pdu->hdr.hlen + hdgst);

        cmd->common.opcode = nvme_admin_async_event;
        cmd->common.command_id = NVME_AQ_BLK_MQ_DEPTH;
        cmd->common.flags |= NVME_CMD_SGL_METABUF;
        nvme_tcp_set_sg_null(cmd);

        ctrl->async_req.state = NVME_TCP_SEND_CMD_PDU;
        ctrl->async_req.offset = 0;
        ctrl->async_req.curr_bio = NULL;
        ctrl->async_req.data_len = 0;

        nvme_tcp_queue_request(&ctrl->async_req, true);
}

static enum blk_eh_timer_return
nvme_tcp_timeout(struct request *rq, bool reserved)
{
        struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
        struct nvme_tcp_ctrl *ctrl = req->queue->ctrl;
        struct nvme_tcp_cmd_pdu *pdu = req->pdu;

        /*
         * Restart the timer if a controller reset is already scheduled. Any
         * timed out commands would be handled before entering the connecting
         * state.
         */
        if (ctrl->ctrl.state == NVME_CTRL_RESETTING)
                return BLK_EH_RESET_TIMER;

        dev_warn(ctrl->ctrl.device,
                "queue %d: timeout request %#x type %d\n",
                nvme_tcp_queue_id(req->queue), rq->tag, pdu->hdr.type);

        if (ctrl->ctrl.state != NVME_CTRL_LIVE) {
                /*
                 * Teardown immediately if controller times out while starting
                 * or we are already started error recovery. all outstanding
                 * requests are completed on shutdown, so we return BLK_EH_DONE.
                 */
                flush_work(&ctrl->err_work);
                nvme_tcp_teardown_io_queues(&ctrl->ctrl, false);
                nvme_tcp_teardown_admin_queue(&ctrl->ctrl, false);
                return BLK_EH_DONE;
        }

        dev_warn(ctrl->ctrl.device, "starting error recovery\n");
        nvme_tcp_error_recovery(&ctrl->ctrl);

        return BLK_EH_RESET_TIMER;
}

static blk_status_t nvme_tcp_map_data(struct nvme_tcp_queue *queue,
                        struct request *rq)
{
        struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
        struct nvme_tcp_cmd_pdu *pdu = req->pdu;
        struct nvme_command *c = &pdu->cmd;

        c->common.flags |= NVME_CMD_SGL_METABUF;

        if (!blk_rq_nr_phys_segments(rq))
                nvme_tcp_set_sg_null(c);
        else if (rq_data_dir(rq) == WRITE &&
            req->data_len <= nvme_tcp_inline_data_size(queue))
                nvme_tcp_set_sg_inline(queue, c, req->data_len);
        else
                nvme_tcp_set_sg_host_data(c, req->data_len);

        return 0;
}

static blk_status_t nvme_tcp_setup_cmd_pdu(struct nvme_ns *ns,
                struct request *rq)
{
        struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
        struct nvme_tcp_cmd_pdu *pdu = req->pdu;
        struct nvme_tcp_queue *queue = req->queue;
        u8 hdgst = nvme_tcp_hdgst_len(queue), ddgst = 0;
        blk_status_t ret;

        ret = nvme_setup_cmd(ns, rq, &pdu->cmd);
        if (ret)
                return ret;

        req->state = NVME_TCP_SEND_CMD_PDU;
        req->offset = 0;
        req->data_sent = 0;
        req->pdu_len = 0;
        req->pdu_sent = 0;
        req->data_len = blk_rq_nr_phys_segments(rq) ?
                                blk_rq_payload_bytes(rq) : 0;
        req->curr_bio = rq->bio;

        if (rq_data_dir(rq) == WRITE &&
            req->data_len <= nvme_tcp_inline_data_size(queue))
                req->pdu_len = req->data_len;
        else if (req->curr_bio)
                nvme_tcp_init_iter(req, READ);

        pdu->hdr.type = nvme_tcp_cmd;
        pdu->hdr.flags = 0;
        if (queue->hdr_digest)
                pdu->hdr.flags |= NVME_TCP_F_HDGST;
        if (queue->data_digest && req->pdu_len) {
                pdu->hdr.flags |= NVME_TCP_F_DDGST;
                ddgst = nvme_tcp_ddgst_len(queue);
        }
        pdu->hdr.hlen = sizeof(*pdu);
        pdu->hdr.pdo = req->pdu_len ? pdu->hdr.hlen + hdgst : 0;
        pdu->hdr.plen =
                cpu_to_le32(pdu->hdr.hlen + hdgst + req->pdu_len + ddgst);

        ret = nvme_tcp_map_data(queue, rq);
        if (unlikely(ret)) {
                nvme_cleanup_cmd(rq);
                dev_err(queue->ctrl->ctrl.device,
                        "Failed to map data (%d)\n", ret);
                return ret;
        }

        return 0;
}

static blk_status_t nvme_tcp_queue_rq(struct blk_mq_hw_ctx *hctx,
                const struct blk_mq_queue_data *bd)
{
        struct nvme_ns *ns = hctx->queue->queuedata;
        struct nvme_tcp_queue *queue = hctx->driver_data;
        struct request *rq = bd->rq;
        struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
        bool queue_ready = test_bit(NVME_TCP_Q_LIVE, &queue->flags);
        blk_status_t ret;

        if (!nvmf_check_ready(&queue->ctrl->ctrl, rq, queue_ready))
                return nvmf_fail_nonready_command(&queue->ctrl->ctrl, rq);

        ret = nvme_tcp_setup_cmd_pdu(ns, rq);
        if (unlikely(ret))
                return ret;

        blk_mq_start_request(rq);

        nvme_tcp_queue_request(req, true);

        return BLK_STS_OK;
}

static int nvme_tcp_map_queues(struct blk_mq_tag_set *set)
{
        struct nvme_tcp_ctrl *ctrl = set->driver_data;
        struct nvmf_ctrl_options *opts = ctrl->ctrl.opts;

        if (opts->nr_write_queues && ctrl->io_queues[HCTX_TYPE_READ]) {
                /* separate read/write queues */
                set->map[HCTX_TYPE_DEFAULT].nr_queues =
                        ctrl->io_queues[HCTX_TYPE_DEFAULT];
                set->map[HCTX_TYPE_DEFAULT].queue_offset = 0;
                set->map[HCTX_TYPE_READ].nr_queues =
                        ctrl->io_queues[HCTX_TYPE_READ];
                set->map[HCTX_TYPE_READ].queue_offset =
                        ctrl->io_queues[HCTX_TYPE_DEFAULT];
        } else {
                /* shared read/write queues */
                set->map[HCTX_TYPE_DEFAULT].nr_queues =
                        ctrl->io_queues[HCTX_TYPE_DEFAULT];
                set->map[HCTX_TYPE_DEFAULT].queue_offset = 0;
                set->map[HCTX_TYPE_READ].nr_queues =
                        ctrl->io_queues[HCTX_TYPE_DEFAULT];
                set->map[HCTX_TYPE_READ].queue_offset = 0;
        }
        blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
        blk_mq_map_queues(&set->map[HCTX_TYPE_READ]);

        if (opts->nr_poll_queues && ctrl->io_queues[HCTX_TYPE_POLL]) {
                /* map dedicated poll queues only if we have queues left */
                set->map[HCTX_TYPE_POLL].nr_queues =
                                ctrl->io_queues[HCTX_TYPE_POLL];
                set->map[HCTX_TYPE_POLL].queue_offset =
                        ctrl->io_queues[HCTX_TYPE_DEFAULT] +
                        ctrl->io_queues[HCTX_TYPE_READ];
                blk_mq_map_queues(&set->map[HCTX_TYPE_POLL]);
        }

        dev_info(ctrl->ctrl.device,
                "mapped %d/%d/%d default/read/poll queues.\n",
                ctrl->io_queues[HCTX_TYPE_DEFAULT],
                ctrl->io_queues[HCTX_TYPE_READ],
                ctrl->io_queues[HCTX_TYPE_POLL]);

        return 0;
}

static int nvme_tcp_poll(struct blk_mq_hw_ctx *hctx)
{
        struct nvme_tcp_queue *queue = hctx->driver_data;
        struct sock *sk = queue->sock->sk;

        if (!test_bit(NVME_TCP_Q_LIVE, &queue->flags))
                return 0;

        set_bit(NVME_TCP_Q_POLLING, &queue->flags);
        if (sk_can_busy_loop(sk) && skb_queue_empty_lockless(&sk->sk_receive_queue))
                sk_busy_loop(sk, true);
        nvme_tcp_try_recv(queue);
        clear_bit(NVME_TCP_Q_POLLING, &queue->flags);
        return queue->nr_cqe;
}

static const struct blk_mq_ops nvme_tcp_mq_ops = {
        .queue_rq       = nvme_tcp_queue_rq,
        .complete       = nvme_complete_rq,
        .init_request   = nvme_tcp_init_request,
        .exit_request   = nvme_tcp_exit_request,
        .init_hctx      = nvme_tcp_init_hctx,
        .timeout        = nvme_tcp_timeout,
        .map_queues     = nvme_tcp_map_queues,
        .poll           = nvme_tcp_poll,
};

static const struct blk_mq_ops nvme_tcp_admin_mq_ops = {
        .queue_rq       = nvme_tcp_queue_rq,
        .complete       = nvme_complete_rq,
        .init_request   = nvme_tcp_init_request,
        .exit_request   = nvme_tcp_exit_request,
        .init_hctx      = nvme_tcp_init_admin_hctx,
        .timeout        = nvme_tcp_timeout,
};

static const struct nvme_ctrl_ops nvme_tcp_ctrl_ops = {
        .name                   = "tcp",
        .module                 = THIS_MODULE,
        .flags                  = NVME_F_FABRICS,
        .reg_read32             = nvmf_reg_read32,
        .reg_read64             = nvmf_reg_read64,
        .reg_write32            = nvmf_reg_write32,
        .free_ctrl              = nvme_tcp_free_ctrl,
        .submit_async_event     = nvme_tcp_submit_async_event,
        .delete_ctrl            = nvme_tcp_delete_ctrl,
        .get_address            = nvmf_get_address,
};

static bool
nvme_tcp_existing_controller(struct nvmf_ctrl_options *opts)
{
        struct nvme_tcp_ctrl *ctrl;
        bool found = false;

        mutex_lock(&nvme_tcp_ctrl_mutex);
        list_for_each_entry(ctrl, &nvme_tcp_ctrl_list, list) {
                found = nvmf_ip_options_match(&ctrl->ctrl, opts);
                if (found)
                        break;
        }
        mutex_unlock(&nvme_tcp_ctrl_mutex);

        return found;
}

static struct nvme_ctrl *nvme_tcp_create_ctrl(struct device *dev,
                struct nvmf_ctrl_options *opts)
{
        struct nvme_tcp_ctrl *ctrl;
        int ret;

        ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
        if (!ctrl)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&ctrl->list);
        ctrl->ctrl.opts = opts;
        ctrl->ctrl.queue_count = opts->nr_io_queues + opts->nr_write_queues +
                                opts->nr_poll_queues + 1;
        ctrl->ctrl.sqsize = opts->queue_size - 1;
        ctrl->ctrl.kato = opts->kato;

        INIT_DELAYED_WORK(&ctrl->connect_work,
                        nvme_tcp_reconnect_ctrl_work);
        INIT_WORK(&ctrl->err_work, nvme_tcp_error_recovery_work);
        INIT_WORK(&ctrl->ctrl.reset_work, nvme_reset_ctrl_work);

        if (!(opts->mask & NVMF_OPT_TRSVCID)) {
                opts->trsvcid =
                        kstrdup(__stringify(NVME_TCP_DISC_PORT), GFP_KERNEL);
                if (!opts->trsvcid) {
                        ret = -ENOMEM;
                        goto out_free_ctrl;
                }
                opts->mask |= NVMF_OPT_TRSVCID;
        }

        ret = inet_pton_with_scope(&init_net, AF_UNSPEC,
                        opts->traddr, opts->trsvcid, &ctrl->addr);
        if (ret) {
                pr_err("malformed address passed: %s:%s\n",
                        opts->traddr, opts->trsvcid);
                goto out_free_ctrl;
        }

        if (opts->mask & NVMF_OPT_HOST_TRADDR) {
                ret = inet_pton_with_scope(&init_net, AF_UNSPEC,
                        opts->host_traddr, NULL, &ctrl->src_addr);
                if (ret) {
                        pr_err("malformed src address passed: %s\n",
                               opts->host_traddr);
                        goto out_free_ctrl;
                }
        }

        if (!opts->duplicate_connect && nvme_tcp_existing_controller(opts)) {
                ret = -EALREADY;
                goto out_free_ctrl;
        }

        ctrl->queues = kcalloc(ctrl->ctrl.queue_count, sizeof(*ctrl->queues),
                                GFP_KERNEL);
        if (!ctrl->queues) {
                ret = -ENOMEM;
                goto out_free_ctrl;
        }

        ret = nvme_init_ctrl(&ctrl->ctrl, dev, &nvme_tcp_ctrl_ops, 0);
        if (ret)
                goto out_kfree_queues;

        if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_CONNECTING)) {
                WARN_ON_ONCE(1);
                ret = -EINTR;
                goto out_uninit_ctrl;
        }

        ret = nvme_tcp_setup_ctrl(&ctrl->ctrl, true);
        if (ret)
                goto out_uninit_ctrl;

        dev_info(ctrl->ctrl.device, "new ctrl: NQN \"%s\", addr %pISp\n",
                ctrl->ctrl.opts->subsysnqn, &ctrl->addr);

        mutex_lock(&nvme_tcp_ctrl_mutex);
        list_add_tail(&ctrl->list, &nvme_tcp_ctrl_list);
        mutex_unlock(&nvme_tcp_ctrl_mutex);

        return &ctrl->ctrl;

out_uninit_ctrl:
        nvme_uninit_ctrl(&ctrl->ctrl);
        nvme_put_ctrl(&ctrl->ctrl);
        if (ret > 0)
                ret = -EIO;
        return ERR_PTR(ret);
out_kfree_queues:
        kfree(ctrl->queues);
out_free_ctrl:
        kfree(ctrl);
        return ERR_PTR(ret);
}

static struct nvmf_transport_ops nvme_tcp_transport = {
        .name           = "tcp",
        .module         = THIS_MODULE,
        .required_opts  = NVMF_OPT_TRADDR,
        .allowed_opts   = NVMF_OPT_TRSVCID | NVMF_OPT_RECONNECT_DELAY |
                          NVMF_OPT_HOST_TRADDR | NVMF_OPT_CTRL_LOSS_TMO |
                          NVMF_OPT_HDR_DIGEST | NVMF_OPT_DATA_DIGEST |
                          NVMF_OPT_NR_WRITE_QUEUES | NVMF_OPT_NR_POLL_QUEUES |
                          NVMF_OPT_TOS,
        .create_ctrl    = nvme_tcp_create_ctrl,
};

static int __init nvme_tcp_init_module(void)
{
        nvme_tcp_wq = alloc_workqueue("nvme_tcp_wq",
                        WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
        if (!nvme_tcp_wq)
                return -ENOMEM;

        nvmf_register_transport(&nvme_tcp_transport);
        return 0;
}

static void __exit nvme_tcp_cleanup_module(void)
{
        struct nvme_tcp_ctrl *ctrl;

        nvmf_unregister_transport(&nvme_tcp_transport);

        mutex_lock(&nvme_tcp_ctrl_mutex);
        list_for_each_entry(ctrl, &nvme_tcp_ctrl_list, list)
                nvme_delete_ctrl(&ctrl->ctrl);
        mutex_unlock(&nvme_tcp_ctrl_mutex);
        flush_workqueue(nvme_delete_wq);

        destroy_workqueue(nvme_tcp_wq);
}

module_init(nvme_tcp_init_module);
module_exit(nvme_tcp_cleanup_module);

MODULE_LICENSE("GPL v2");