/*
 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the BSD-type
 * license below:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *      Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *      Redistributions in binary form must reproduce the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer in the documentation and/or other materials provided
 *      with the distribution.
 *
 *      Neither the name of the Network Appliance, Inc. nor the names of
 *      its contributors may be used to endorse or promote products
 *      derived from this software without specific prior written
 *      permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * transport.c
 *
 * This file contains the top-level implementation of an RPC RDMA
 * transport.
 *
 * Naming convention: functions beginning with xprt_ are part of the
 * transport switch. All others are RPC RDMA internal.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/seq_file.h>

#include "xprt_rdma.h"

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY        RPCDBG_TRANS
#endif

MODULE_LICENSE("Dual BSD/GPL");

MODULE_DESCRIPTION("RPC/RDMA Transport for Linux kernel NFS");
MODULE_AUTHOR("Network Appliance, Inc.");

/*
 * tunables
 */

static unsigned int xprt_rdma_slot_table_entries = RPCRDMA_DEF_SLOT_TABLE;
static unsigned int xprt_rdma_max_inline_read = RPCRDMA_DEF_INLINE;
static unsigned int xprt_rdma_max_inline_write = RPCRDMA_DEF_INLINE;
static unsigned int xprt_rdma_inline_write_padding;
static unsigned int xprt_rdma_memreg_strategy = RPCRDMA_FRMR;
                int xprt_rdma_pad_optimize = 0;

#ifdef RPC_DEBUG

static unsigned int min_slot_table_size = RPCRDMA_MIN_SLOT_TABLE;
static unsigned int max_slot_table_size = RPCRDMA_MAX_SLOT_TABLE;
static unsigned int zero;
static unsigned int max_padding = PAGE_SIZE;
static unsigned int min_memreg = RPCRDMA_BOUNCEBUFFERS;
static unsigned int max_memreg = RPCRDMA_LAST - 1;

static struct ctl_table_header *sunrpc_table_header;

static ctl_table xr_tunables_table[] = {
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "rdma_slot_table_entries",
                .data           = &xprt_rdma_slot_table_entries,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec_minmax,
                .strategy       = &sysctl_intvec,
                .extra1         = &min_slot_table_size,
                .extra2         = &max_slot_table_size
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "rdma_max_inline_read",
                .data           = &xprt_rdma_max_inline_read,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
                .strategy       = &sysctl_intvec,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "rdma_max_inline_write",
                .data           = &xprt_rdma_max_inline_write,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
                .strategy       = &sysctl_intvec,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "rdma_inline_write_padding",
                .data           = &xprt_rdma_inline_write_padding,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec_minmax,
                .strategy       = &sysctl_intvec,
                .extra1         = &zero,
                .extra2         = &max_padding,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "rdma_memreg_strategy",
                .data           = &xprt_rdma_memreg_strategy,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec_minmax,
                .strategy       = &sysctl_intvec,
                .extra1         = &min_memreg,
                .extra2         = &max_memreg,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "rdma_pad_optimize",
                .data           = &xprt_rdma_pad_optimize,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
        },
        {
                .ctl_name = 0,
        },
};

static ctl_table sunrpc_table[] = {
        {
                .ctl_name       = CTL_SUNRPC,
                .procname       = "sunrpc",
                .mode           = 0555,
                .child          = xr_tunables_table
        },
        {
                .ctl_name = 0,
        },
};

#endif

static struct rpc_xprt_ops xprt_rdma_procs;     /* forward reference */

static void
xprt_rdma_format_addresses(struct rpc_xprt *xprt)
{
        struct sockaddr *sap = (struct sockaddr *)
                                        &rpcx_to_rdmad(xprt).addr;
        struct sockaddr_in *sin = (struct sockaddr_in *)sap;
        char buf[64];

        (void)rpc_ntop(sap, buf, sizeof(buf));
        xprt->address_strings[RPC_DISPLAY_ADDR] = kstrdup(buf, GFP_KERNEL);

        (void)snprintf(buf, sizeof(buf), "%u", rpc_get_port(sap));
        xprt->address_strings[RPC_DISPLAY_PORT] = kstrdup(buf, GFP_KERNEL);

        xprt->address_strings[RPC_DISPLAY_PROTO] = "rdma";

        (void)snprintf(buf, sizeof(buf), "%02x%02x%02x%02x",
                                NIPQUAD(sin->sin_addr.s_addr));
        xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = kstrdup(buf, GFP_KERNEL);

        (void)snprintf(buf, sizeof(buf), "%4hx", rpc_get_port(sap));
        xprt->address_strings[RPC_DISPLAY_HEX_PORT] = kstrdup(buf, GFP_KERNEL);

        /* netid */
        xprt->address_strings[RPC_DISPLAY_NETID] = "rdma";
}

static void
xprt_rdma_free_addresses(struct rpc_xprt *xprt)
{
        unsigned int i;

        for (i = 0; i < RPC_DISPLAY_MAX; i++)
                switch (i) {
                case RPC_DISPLAY_PROTO:
                case RPC_DISPLAY_NETID:
                        continue;
                default:
                        kfree(xprt->address_strings[i]);
                }
}

static void
xprt_rdma_connect_worker(struct work_struct *work)
{
        struct rpcrdma_xprt *r_xprt =
                container_of(work, struct rpcrdma_xprt, rdma_connect.work);
        struct rpc_xprt *xprt = &r_xprt->xprt;
        int rc = 0;

        if (!xprt->shutdown) {
                xprt_clear_connected(xprt);

                dprintk("RPC:       %s: %sconnect\n", __func__,
                                r_xprt->rx_ep.rep_connected != 0 ? "re" : "");
                rc = rpcrdma_ep_connect(&r_xprt->rx_ep, &r_xprt->rx_ia);
                if (rc)
                        goto out;
        }
        goto out_clear;

out:
        xprt_wake_pending_tasks(xprt, rc);

out_clear:
        dprintk("RPC:       %s: exit\n", __func__);
        xprt_clear_connecting(xprt);
}

/*
 * xprt_rdma_destroy
 *
 * Destroy the xprt.
 * Free all memory associated with the object, including its own.
 * NOTE: none of the *destroy methods free memory for their top-level
 * objects, even though they may have allocated it (they do free
 * private memory). It's up to the caller to handle it. In this
 * case (RDMA transport), all structure memory is inlined with the
 * struct rpcrdma_xprt.
 */
static void
xprt_rdma_destroy(struct rpc_xprt *xprt)
{
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
        int rc;

        dprintk("RPC:       %s: called\n", __func__);

        cancel_delayed_work(&r_xprt->rdma_connect);
        flush_scheduled_work();

        xprt_clear_connected(xprt);

        rpcrdma_buffer_destroy(&r_xprt->rx_buf);
        rc = rpcrdma_ep_destroy(&r_xprt->rx_ep, &r_xprt->rx_ia);
        if (rc)
                dprintk("RPC:       %s: rpcrdma_ep_destroy returned %i\n",
                        __func__, rc);
        rpcrdma_ia_close(&r_xprt->rx_ia);

        xprt_rdma_free_addresses(xprt);

        kfree(xprt->slot);
        xprt->slot = NULL;
        kfree(xprt);

        dprintk("RPC:       %s: returning\n", __func__);

        module_put(THIS_MODULE);
}

static const struct rpc_timeout xprt_rdma_default_timeout = {
        .to_initval = 60 * HZ,
        .to_maxval = 60 * HZ,
};

/**
 * xprt_setup_rdma - Set up transport to use RDMA
 *
 * @args: rpc transport arguments
 */
static struct rpc_xprt *
xprt_setup_rdma(struct xprt_create *args)
{
        struct rpcrdma_create_data_internal cdata;
        struct rpc_xprt *xprt;
        struct rpcrdma_xprt *new_xprt;
        struct rpcrdma_ep *new_ep;
        struct sockaddr_in *sin;
        int rc;

        if (args->addrlen > sizeof(xprt->addr)) {
                dprintk("RPC:       %s: address too large\n", __func__);
                return ERR_PTR(-EBADF);
        }

        xprt = kzalloc(sizeof(struct rpcrdma_xprt), GFP_KERNEL);
        if (xprt == NULL) {
                dprintk("RPC:       %s: couldn't allocate rpcrdma_xprt\n",
                        __func__);
                return ERR_PTR(-ENOMEM);
        }

        xprt->max_reqs = xprt_rdma_slot_table_entries;
        xprt->slot = kcalloc(xprt->max_reqs,
                                sizeof(struct rpc_rqst), GFP_KERNEL);
        if (xprt->slot == NULL) {
                dprintk("RPC:       %s: couldn't allocate %d slots\n",
                        __func__, xprt->max_reqs);
                kfree(xprt);
                return ERR_PTR(-ENOMEM);
        }

        /* 60 second timeout, no retries */
        xprt->timeout = &xprt_rdma_default_timeout;
        xprt->bind_timeout = (60U * HZ);
        xprt->connect_timeout = (60U * HZ);
        xprt->reestablish_timeout = (5U * HZ);
        xprt->idle_timeout = (5U * 60 * HZ);

        xprt->resvport = 0;             /* privileged port not needed */
        xprt->tsh_size = 0;             /* RPC-RDMA handles framing */
        xprt->max_payload = RPCRDMA_MAX_DATA_SEGS * PAGE_SIZE;
        xprt->ops = &xprt_rdma_procs;

        /*
         * Set up RDMA-specific connect data.
         */

        /* Put server RDMA address in local cdata */
        memcpy(&cdata.addr, args->dstaddr, args->addrlen);

        /* Ensure xprt->addr holds valid server TCP (not RDMA)
         * address, for any side protocols which peek at it */
        xprt->prot = IPPROTO_TCP;
        xprt->addrlen = args->addrlen;
        memcpy(&xprt->addr, &cdata.addr, xprt->addrlen);

        sin = (struct sockaddr_in *)&cdata.addr;
        if (ntohs(sin->sin_port) != 0)
                xprt_set_bound(xprt);

        dprintk("RPC:       %s: %pI4:%u\n",
                __func__, &sin->sin_addr.s_addr, ntohs(sin->sin_port));

        /* Set max requests */
        cdata.max_requests = xprt->max_reqs;

        /* Set some length limits */
        cdata.rsize = RPCRDMA_MAX_SEGS * PAGE_SIZE; /* RDMA write max */
        cdata.wsize = RPCRDMA_MAX_SEGS * PAGE_SIZE; /* RDMA read max */

        cdata.inline_wsize = xprt_rdma_max_inline_write;
        if (cdata.inline_wsize > cdata.wsize)
                cdata.inline_wsize = cdata.wsize;

        cdata.inline_rsize = xprt_rdma_max_inline_read;
        if (cdata.inline_rsize > cdata.rsize)
                cdata.inline_rsize = cdata.rsize;

        cdata.padding = xprt_rdma_inline_write_padding;

        /*
         * Create new transport instance, which includes initialized
         *  o ia
         *  o endpoint
         *  o buffers
         */

        new_xprt = rpcx_to_rdmax(xprt);

        rc = rpcrdma_ia_open(new_xprt, (struct sockaddr *) &cdata.addr,
                                xprt_rdma_memreg_strategy);
        if (rc)
                goto out1;

        /*
         * initialize and create ep
         */
        new_xprt->rx_data = cdata;
        new_ep = &new_xprt->rx_ep;
        new_ep->rep_remote_addr = cdata.addr;

        rc = rpcrdma_ep_create(&new_xprt->rx_ep,
                                &new_xprt->rx_ia, &new_xprt->rx_data);
        if (rc)
                goto out2;

        /*
         * Allocate pre-registered send and receive buffers for headers and
         * any inline data. Also specify any padding which will be provided
         * from a preregistered zero buffer.
         */
        rc = rpcrdma_buffer_create(&new_xprt->rx_buf, new_ep, &new_xprt->rx_ia,
                                &new_xprt->rx_data);
        if (rc)
                goto out3;

        /*
         * Register a callback for connection events. This is necessary because
         * connection loss notification is async. We also catch connection loss
         * when reaping receives.
         */
        INIT_DELAYED_WORK(&new_xprt->rdma_connect, xprt_rdma_connect_worker);
        new_ep->rep_func = rpcrdma_conn_func;
        new_ep->rep_xprt = xprt;

        xprt_rdma_format_addresses(xprt);

        if (!try_module_get(THIS_MODULE))
                goto out4;

        return xprt;

out4:
        xprt_rdma_free_addresses(xprt);
        rc = -EINVAL;
out3:
        (void) rpcrdma_ep_destroy(new_ep, &new_xprt->rx_ia);
out2:
        rpcrdma_ia_close(&new_xprt->rx_ia);
out1:
        kfree(xprt->slot);
        kfree(xprt);
        return ERR_PTR(rc);
}

/*
 * Close a connection, during shutdown or timeout/reconnect
 */
static void
xprt_rdma_close(struct rpc_xprt *xprt)
{
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

        dprintk("RPC:       %s: closing\n", __func__);
        if (r_xprt->rx_ep.rep_connected > 0)
                xprt->reestablish_timeout = 0;
        xprt_disconnect_done(xprt);
        (void) rpcrdma_ep_disconnect(&r_xprt->rx_ep, &r_xprt->rx_ia);
}

static void
xprt_rdma_set_port(struct rpc_xprt *xprt, u16 port)
{
        struct sockaddr_in *sap;

        sap = (struct sockaddr_in *)&xprt->addr;
        sap->sin_port = htons(port);
        sap = (struct sockaddr_in *)&rpcx_to_rdmad(xprt).addr;
        sap->sin_port = htons(port);
        dprintk("RPC:       %s: %u\n", __func__, port);
}

static void
xprt_rdma_connect(struct rpc_task *task)
{
        struct rpc_xprt *xprt = (struct rpc_xprt *)task->tk_xprt;
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

        if (!xprt_test_and_set_connecting(xprt)) {
                if (r_xprt->rx_ep.rep_connected != 0) {
                        /* Reconnect */
                        schedule_delayed_work(&r_xprt->rdma_connect,
                                xprt->reestablish_timeout);
                        xprt->reestablish_timeout <<= 1;
                        if (xprt->reestablish_timeout > (30 * HZ))
                                xprt->reestablish_timeout = (30 * HZ);
                        else if (xprt->reestablish_timeout < (5 * HZ))
                                xprt->reestablish_timeout = (5 * HZ);
                } else {
                        schedule_delayed_work(&r_xprt->rdma_connect, 0);
                        if (!RPC_IS_ASYNC(task))
                                flush_scheduled_work();
                }
        }
}

static int
xprt_rdma_reserve_xprt(struct rpc_task *task)
{
        struct rpc_xprt *xprt = task->tk_xprt;
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
        int credits = atomic_read(&r_xprt->rx_buf.rb_credits);

        /* == RPC_CWNDSCALE @ init, but *after* setup */
        if (r_xprt->rx_buf.rb_cwndscale == 0UL) {
                r_xprt->rx_buf.rb_cwndscale = xprt->cwnd;
                dprintk("RPC:       %s: cwndscale %lu\n", __func__,
                        r_xprt->rx_buf.rb_cwndscale);
                BUG_ON(r_xprt->rx_buf.rb_cwndscale <= 0);
        }
        xprt->cwnd = credits * r_xprt->rx_buf.rb_cwndscale;
        return xprt_reserve_xprt_cong(task);
}

/*
 * The RDMA allocate/free functions need the task structure as a place
 * to hide the struct rpcrdma_req, which is necessary for the actual send/recv
 * sequence. For this reason, the recv buffers are attached to send
 * buffers for portions of the RPC. Note that the RPC layer allocates
 * both send and receive buffers in the same call. We may register
 * the receive buffer portion when using reply chunks.
 */
static void *
xprt_rdma_allocate(struct rpc_task *task, size_t size)
{
        struct rpc_xprt *xprt = task->tk_xprt;
        struct rpcrdma_req *req, *nreq;

        req = rpcrdma_buffer_get(&rpcx_to_rdmax(xprt)->rx_buf);
        BUG_ON(NULL == req);

        if (size > req->rl_size) {
                dprintk("RPC:       %s: size %zd too large for buffer[%zd]: "
                        "prog %d vers %d proc %d\n",
                        __func__, size, req->rl_size,
                        task->tk_client->cl_prog, task->tk_client->cl_vers,
                        task->tk_msg.rpc_proc->p_proc);
                /*
                 * Outgoing length shortage. Our inline write max must have
                 * been configured to perform direct i/o.
                 *
                 * This is therefore a large metadata operation, and the
                 * allocate call was made on the maximum possible message,
                 * e.g. containing long filename(s) or symlink data. In
                 * fact, while these metadata operations *might* carry
                 * large outgoing payloads, they rarely *do*. However, we
                 * have to commit to the request here, so reallocate and
                 * register it now. The data path will never require this
                 * reallocation.
                 *
                 * If the allocation or registration fails, the RPC framework
                 * will (doggedly) retry.
                 */
                if (rpcx_to_rdmax(xprt)->rx_ia.ri_memreg_strategy ==
                                RPCRDMA_BOUNCEBUFFERS) {
                        /* forced to "pure inline" */
                        dprintk("RPC:       %s: too much data (%zd) for inline "
                                        "(r/w max %d/%d)\n", __func__, size,
                                        rpcx_to_rdmad(xprt).inline_rsize,
                                        rpcx_to_rdmad(xprt).inline_wsize);
                        size = req->rl_size;
                        rpc_exit(task, -EIO);           /* fail the operation */
                        rpcx_to_rdmax(xprt)->rx_stats.failed_marshal_count++;
                        goto out;
                }
                if (task->tk_flags & RPC_TASK_SWAPPER)
                        nreq = kmalloc(sizeof *req + size, GFP_ATOMIC);
                else
                        nreq = kmalloc(sizeof *req + size, GFP_NOFS);
                if (nreq == NULL)
                        goto outfail;

                if (rpcrdma_register_internal(&rpcx_to_rdmax(xprt)->rx_ia,
                                nreq->rl_base, size + sizeof(struct rpcrdma_req)
                                - offsetof(struct rpcrdma_req, rl_base),
                                &nreq->rl_handle, &nreq->rl_iov)) {
                        kfree(nreq);
                        goto outfail;
                }
                rpcx_to_rdmax(xprt)->rx_stats.hardway_register_count += size;
                nreq->rl_size = size;
                nreq->rl_niovs = 0;
                nreq->rl_nchunks = 0;
                nreq->rl_buffer = (struct rpcrdma_buffer *)req;
                nreq->rl_reply = req->rl_reply;
                memcpy(nreq->rl_segments,
                        req->rl_segments, sizeof nreq->rl_segments);
                /* flag the swap with an unused field */
                nreq->rl_iov.length = 0;
                req->rl_reply = NULL;
                req = nreq;
        }
        dprintk("RPC:       %s: size %zd, request 0x%p\n", __func__, size, req);
out:
        req->rl_connect_cookie = 0;     /* our reserved value */
        return req->rl_xdr_buf;

outfail:
        rpcrdma_buffer_put(req);
        rpcx_to_rdmax(xprt)->rx_stats.failed_marshal_count++;
        return NULL;
}

/*
 * This function returns all RDMA resources to the pool.
 */
static void
xprt_rdma_free(void *buffer)
{
        struct rpcrdma_req *req;
        struct rpcrdma_xprt *r_xprt;
        struct rpcrdma_rep *rep;
        int i;

        if (buffer == NULL)
                return;

        req = container_of(buffer, struct rpcrdma_req, rl_xdr_buf[0]);
        if (req->rl_iov.length == 0) {  /* see allocate above */
                r_xprt = container_of(((struct rpcrdma_req *) req->rl_buffer)->rl_buffer,
                                      struct rpcrdma_xprt, rx_buf);
        } else
                r_xprt = container_of(req->rl_buffer, struct rpcrdma_xprt, rx_buf);
        rep = req->rl_reply;

        dprintk("RPC:       %s: called on 0x%p%s\n",
                __func__, rep, (rep && rep->rr_func) ? " (with waiter)" : "");

        /*
         * Finish the deregistration. When using mw bind, this was
         * begun in rpcrdma_reply_handler(). In all other modes, we
         * do it here, in thread context. The process is considered
         * complete when the rr_func vector becomes NULL - this
         * was put in place during rpcrdma_reply_handler() - the wait
         * call below will not block if the dereg is "done". If
         * interrupted, our framework will clean up.
         */
        for (i = 0; req->rl_nchunks;) {
                --req->rl_nchunks;
                i += rpcrdma_deregister_external(
                        &req->rl_segments[i], r_xprt, NULL);
        }

        if (rep && wait_event_interruptible(rep->rr_unbind, !rep->rr_func)) {
                rep->rr_func = NULL;    /* abandon the callback */
                req->rl_reply = NULL;
        }

        if (req->rl_iov.length == 0) {  /* see allocate above */
                struct rpcrdma_req *oreq = (struct rpcrdma_req *)req->rl_buffer;
                oreq->rl_reply = req->rl_reply;
                (void) rpcrdma_deregister_internal(&r_xprt->rx_ia,
                                                   req->rl_handle,
                                                   &req->rl_iov);
                kfree(req);
                req = oreq;
        }

        /* Put back request+reply buffers */
        rpcrdma_buffer_put(req);
}

/*
 * send_request invokes the meat of RPC RDMA. It must do the following:
 *  1.  Marshal the RPC request into an RPC RDMA request, which means
 *      putting a header in front of data, and creating IOVs for RDMA
 *      from those in the request.
 *  2.  In marshaling, detect opportunities for RDMA, and use them.
 *  3.  Post a recv message to set up asynch completion, then send
 *      the request (rpcrdma_ep_post).
 *  4.  No partial sends are possible in the RPC-RDMA protocol (as in UDP).
 */

static int
xprt_rdma_send_request(struct rpc_task *task)
{
        struct rpc_rqst *rqst = task->tk_rqstp;
        struct rpc_xprt *xprt = task->tk_xprt;
        struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

        /* marshal the send itself */
        if (req->rl_niovs == 0 && rpcrdma_marshal_req(rqst) != 0) {
                r_xprt->rx_stats.failed_marshal_count++;
                dprintk("RPC:       %s: rpcrdma_marshal_req failed\n",
                        __func__);
                return -EIO;
        }

        if (req->rl_reply == NULL)              /* e.g. reconnection */
                rpcrdma_recv_buffer_get(req);

        if (req->rl_reply) {
                req->rl_reply->rr_func = rpcrdma_reply_handler;
                /* this need only be done once, but... */
                req->rl_reply->rr_xprt = xprt;
        }

        /* Must suppress retransmit to maintain credits */
        if (req->rl_connect_cookie == xprt->connect_cookie)
                goto drop_connection;
        req->rl_connect_cookie = xprt->connect_cookie;

        if (rpcrdma_ep_post(&r_xprt->rx_ia, &r_xprt->rx_ep, req))
                goto drop_connection;

        task->tk_bytes_sent += rqst->rq_snd_buf.len;
        rqst->rq_bytes_sent = 0;
        return 0;

drop_connection:
        xprt_disconnect_done(xprt);
        return -ENOTCONN;       /* implies disconnect */
}

static void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
{
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
        long idle_time = 0;

        if (xprt_connected(xprt))
                idle_time = (long)(jiffies - xprt->last_used) / HZ;

        seq_printf(seq,
          "\txprt:\trdma %u %lu %lu %lu %ld %lu %lu %lu %Lu %Lu "
          "%lu %lu %lu %Lu %Lu %Lu %Lu %lu %lu %lu\n",

           0,   /* need a local port? */
           xprt->stat.bind_count,
           xprt->stat.connect_count,
           xprt->stat.connect_time,
           idle_time,
           xprt->stat.sends,
           xprt->stat.recvs,
           xprt->stat.bad_xids,
           xprt->stat.req_u,
           xprt->stat.bklog_u,

           r_xprt->rx_stats.read_chunk_count,
           r_xprt->rx_stats.write_chunk_count,
           r_xprt->rx_stats.reply_chunk_count,
           r_xprt->rx_stats.total_rdma_request,
           r_xprt->rx_stats.total_rdma_reply,
           r_xprt->rx_stats.pullup_copy_count,
           r_xprt->rx_stats.fixup_copy_count,
           r_xprt->rx_stats.hardway_register_count,
           r_xprt->rx_stats.failed_marshal_count,
           r_xprt->rx_stats.bad_reply_count);
}

/*
 * Plumbing for rpc transport switch and kernel module
 */

static struct rpc_xprt_ops xprt_rdma_procs = {
        .reserve_xprt           = xprt_rdma_reserve_xprt,
        .release_xprt           = xprt_release_xprt_cong, /* sunrpc/xprt.c */
        .release_request        = xprt_release_rqst_cong,       /* ditto */
        .set_retrans_timeout    = xprt_set_retrans_timeout_def, /* ditto */
        .rpcbind                = rpcb_getport_async,   /* sunrpc/rpcb_clnt.c */
        .set_port               = xprt_rdma_set_port,
        .connect                = xprt_rdma_connect,
        .buf_alloc              = xprt_rdma_allocate,
        .buf_free               = xprt_rdma_free,
        .send_request           = xprt_rdma_send_request,
        .close                  = xprt_rdma_close,
        .destroy                = xprt_rdma_destroy,
        .print_stats            = xprt_rdma_print_stats
};

static struct xprt_class xprt_rdma = {
        .list                   = LIST_HEAD_INIT(xprt_rdma.list),
        .name                   = "rdma",
        .owner                  = THIS_MODULE,
        .ident                  = XPRT_TRANSPORT_RDMA,
        .setup                  = xprt_setup_rdma,
};

static void __exit xprt_rdma_cleanup(void)
{
        int rc;

        dprintk(KERN_INFO "RPCRDMA Module Removed, deregister RPC RDMA transport\n");
#ifdef RPC_DEBUG
        if (sunrpc_table_header) {
                unregister_sysctl_table(sunrpc_table_header);
                sunrpc_table_header = NULL;
        }
#endif
        rc = xprt_unregister_transport(&xprt_rdma);
        if (rc)
                dprintk("RPC:       %s: xprt_unregister returned %i\n",
                        __func__, rc);
}

static int __init xprt_rdma_init(void)
{
        int rc;

        rc = xprt_register_transport(&xprt_rdma);

        if (rc)
                return rc;

        dprintk(KERN_INFO "RPCRDMA Module Init, register RPC RDMA transport\n");

        dprintk(KERN_INFO "Defaults:\n");
        dprintk(KERN_INFO "\tSlots %d\n"
                "\tMaxInlineRead %d\n\tMaxInlineWrite %d\n",
                xprt_rdma_slot_table_entries,
                xprt_rdma_max_inline_read, xprt_rdma_max_inline_write);
        dprintk(KERN_INFO "\tPadding %d\n\tMemreg %d\n",
                xprt_rdma_inline_write_padding, xprt_rdma_memreg_strategy);

#ifdef RPC_DEBUG
        if (!sunrpc_table_header)
                sunrpc_table_header = register_sysctl_table(sunrpc_table);
#endif
        return 0;
}

module_init(xprt_rdma_init);
module_exit(xprt_rdma_cleanup);