// SPDX-License-Identifier: GPL-2.0-only

  /*
   * linux/fs/9p/trans_rdma.c
   *
   * RDMA transport layer based on the trans_fd.c implementation.
   *
   *  Copyright (C) 2008 by Tom Tucker <tom@opengridcomputing.com>
   *  Copyright (C) 2006 by Russ Cox <rsc@swtch.com>
   *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
   *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
   *  Copyright (C) 1997-2002 by Ron Minnich <rminnich@sarnoff.com>

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/in.h>
  #include <linux/module.h>
  #include <linux/net.h>
  #include <linux/ipv6.h>
  #include <linux/kthread.h>
  #include <linux/errno.h>
  #include <linux/kernel.h>
  #include <linux/un.h>
  #include <linux/uaccess.h>
  #include <linux/inet.h>
  #include <linux/idr.h>
  #include <linux/file.h>
  #include <linux/parser.h>
  #include <linux/semaphore.h>

  #include <linux/slab.h>

  #include <linux/seq_file.h>

  #include <net/9p/9p.h>
  #include <net/9p/client.h>
  #include <net/9p/transport.h>
  #include <rdma/ib_verbs.h>
  #include <rdma/rdma_cm.h>

  
  #define P9_PORT			5640
  #define P9_RDMA_SQ_DEPTH	32
  #define P9_RDMA_RQ_DEPTH	32
  #define P9_RDMA_SEND_SGE	4
  #define P9_RDMA_RECV_SGE	4
  #define P9_RDMA_IRD		0
  #define P9_RDMA_ORD		0
  #define P9_RDMA_TIMEOUT		30000		/* 30 seconds */

  #define P9_RDMA_MAXSIZE		(1024*1024)	/* 1MB */

  /**
   * struct p9_trans_rdma - RDMA transport instance
   *
   * @state: tracks the transport state machine for connection setup and tear down
   * @cm_id: The RDMA CM ID
   * @pd: Protection Domain pointer
   * @qp: Queue Pair pointer
   * @cq: Completion Queue pointer

   * @timeout: Number of uSecs to wait for connection management events

   * @privport: Whether a privileged port may be used
   * @port: The port to use

   * @sq_depth: The depth of the Send Queue
   * @sq_sem: Semaphore for the SQ
   * @rq_depth: The depth of the Receive Queue.

   * @rq_sem: Semaphore for the RQ

   * @excess_rc : Amount of posted Receive Contexts without a pending request.
   *		See rdma_request()

   * @addr: The remote peer's address
   * @req_lock: Protects the active request list

   * @cm_done: Completion event for connection management tracking
   */
  struct p9_trans_rdma {
  	enum {
  		P9_RDMA_INIT,
  		P9_RDMA_ADDR_RESOLVED,
  		P9_RDMA_ROUTE_RESOLVED,
  		P9_RDMA_CONNECTED,
  		P9_RDMA_FLUSHING,
  		P9_RDMA_CLOSING,
  		P9_RDMA_CLOSED,
  	} state;
  	struct rdma_cm_id *cm_id;
  	struct ib_pd *pd;
  	struct ib_qp *qp;
  	struct ib_cq *cq;

  	long timeout;

  	bool privport;
  	u16 port;

  	int sq_depth;
  	struct semaphore sq_sem;
  	int rq_depth;

  	struct semaphore rq_sem;

  	atomic_t excess_rc;

  	struct sockaddr_in addr;
  	spinlock_t req_lock;
  
  	struct completion cm_done;
  };

  struct p9_rdma_req;

  /**

   * struct p9_rdma_context - Keeps track of in-process WR

   *

   * @busa: Bus address to unmap when the WR completes
   * @req: Keeps track of requests (send)
   * @rc: Keepts track of replies (receive)
   */

  struct p9_rdma_context {

  	struct ib_cqe cqe;

  	dma_addr_t busa;
  	union {
  		struct p9_req_t *req;

  		struct p9_fcall rc;

  	};
  };
  
  /**

   * struct p9_rdma_opts - Collection of mount options

   * @port: port of connection
   * @sq_depth: The requested depth of the SQ. This really doesn't need
   * to be any deeper than the number of threads used in the client
   * @rq_depth: The depth of the RQ. Should be greater than or equal to SQ depth
   * @timeout: Time to wait in msecs for CM events
   */
  struct p9_rdma_opts {
  	short port;

  	bool privport;

  	int sq_depth;
  	int rq_depth;
  	long timeout;
  };
  
  /*
   * Option Parsing (code inspired by NFS code)
   */
  enum {
  	/* Options that take integer arguments */

  	Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout,
  	/* Options that take no argument */
  	Opt_privport,
  	Opt_err,

  };
  
  static match_table_t tokens = {
  	{Opt_port, "port=%u"},
  	{Opt_sq_depth, "sq=%u"},
  	{Opt_rq_depth, "rq=%u"},
  	{Opt_timeout, "timeout=%u"},

  	{Opt_privport, "privport"},

  	{Opt_err, NULL},
  };

  static int p9_rdma_show_options(struct seq_file *m, struct p9_client *clnt)
  {
  	struct p9_trans_rdma *rdma = clnt->trans;
  
  	if (rdma->port != P9_PORT)
  		seq_printf(m, ",port=%u", rdma->port);
  	if (rdma->sq_depth != P9_RDMA_SQ_DEPTH)
  		seq_printf(m, ",sq=%u", rdma->sq_depth);
  	if (rdma->rq_depth != P9_RDMA_RQ_DEPTH)
  		seq_printf(m, ",rq=%u", rdma->rq_depth);
  	if (rdma->timeout != P9_RDMA_TIMEOUT)
  		seq_printf(m, ",timeout=%lu", rdma->timeout);
  	if (rdma->privport)
  		seq_puts(m, ",privport");
  	return 0;
  }

  /**

   * parse_opts - parse mount options into rdma options structure
   * @params: options string passed from mount
   * @opts: rdma transport-specific structure to parse options into

   *
   * Returns 0 upon success, -ERRNO upon failure
   */
  static int parse_opts(char *params, struct p9_rdma_opts *opts)
  {
  	char *p;
  	substring_t args[MAX_OPT_ARGS];
  	int option;

  	char *options, *tmp_options;

  
  	opts->port = P9_PORT;
  	opts->sq_depth = P9_RDMA_SQ_DEPTH;
  	opts->rq_depth = P9_RDMA_RQ_DEPTH;
  	opts->timeout = P9_RDMA_TIMEOUT;

  	opts->privport = false;

  
  	if (!params)
  		return 0;

  	tmp_options = kstrdup(params, GFP_KERNEL);
  	if (!tmp_options) {

  		p9_debug(P9_DEBUG_ERROR,
  			 "failed to allocate copy of option string
  ");

  		return -ENOMEM;
  	}

  	options = tmp_options;

  
  	while ((p = strsep(&options, ",")) != NULL) {
  		int token;
  		int r;
  		if (!*p)
  			continue;
  		token = match_token(p, tokens, args);

  		if ((token != Opt_err) && (token != Opt_privport)) {
  			r = match_int(&args[0], &option);
  			if (r < 0) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?
  ");
  				continue;
  			}

  		}
  		switch (token) {
  		case Opt_port:
  			opts->port = option;
  			break;
  		case Opt_sq_depth:
  			opts->sq_depth = option;
  			break;
  		case Opt_rq_depth:
  			opts->rq_depth = option;
  			break;
  		case Opt_timeout:
  			opts->timeout = option;
  			break;

  		case Opt_privport:

  			opts->privport = true;

  			break;

  		default:
  			continue;
  		}
  	}
  	/* RQ must be at least as large as the SQ */
  	opts->rq_depth = max(opts->rq_depth, opts->sq_depth);

  	kfree(tmp_options);

  	return 0;
  }
  
  static int
  p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
  {
  	struct p9_client *c = id->context;
  	struct p9_trans_rdma *rdma = c->trans;
  	switch (event->event) {
  	case RDMA_CM_EVENT_ADDR_RESOLVED:
  		BUG_ON(rdma->state != P9_RDMA_INIT);
  		rdma->state = P9_RDMA_ADDR_RESOLVED;
  		break;
  
  	case RDMA_CM_EVENT_ROUTE_RESOLVED:
  		BUG_ON(rdma->state != P9_RDMA_ADDR_RESOLVED);
  		rdma->state = P9_RDMA_ROUTE_RESOLVED;
  		break;
  
  	case RDMA_CM_EVENT_ESTABLISHED:
  		BUG_ON(rdma->state != P9_RDMA_ROUTE_RESOLVED);
  		rdma->state = P9_RDMA_CONNECTED;
  		break;
  
  	case RDMA_CM_EVENT_DISCONNECTED:
  		if (rdma)
  			rdma->state = P9_RDMA_CLOSED;

  		c->status = Disconnected;

  		break;
  
  	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
  		break;
  
  	case RDMA_CM_EVENT_ADDR_CHANGE:
  	case RDMA_CM_EVENT_ROUTE_ERROR:
  	case RDMA_CM_EVENT_DEVICE_REMOVAL:
  	case RDMA_CM_EVENT_MULTICAST_JOIN:
  	case RDMA_CM_EVENT_MULTICAST_ERROR:
  	case RDMA_CM_EVENT_REJECTED:
  	case RDMA_CM_EVENT_CONNECT_REQUEST:
  	case RDMA_CM_EVENT_CONNECT_RESPONSE:
  	case RDMA_CM_EVENT_CONNECT_ERROR:
  	case RDMA_CM_EVENT_ADDR_ERROR:
  	case RDMA_CM_EVENT_UNREACHABLE:
  		c->status = Disconnected;
  		rdma_disconnect(rdma->cm_id);
  		break;
  	default:
  		BUG();
  	}
  	complete(&rdma->cm_done);
  	return 0;
  }
  
  static void

  recv_done(struct ib_cq *cq, struct ib_wc *wc)

  {

  	struct p9_client *client = cq->cq_context;
  	struct p9_trans_rdma *rdma = client->trans;
  	struct p9_rdma_context *c =
  		container_of(wc->wr_cqe, struct p9_rdma_context, cqe);

  	struct p9_req_t *req;
  	int err = 0;
  	int16_t tag;
  
  	req = NULL;
  	ib_dma_unmap_single(rdma->cm_id->device, c->busa, client->msize,
  							 DMA_FROM_DEVICE);

  	if (wc->status != IB_WC_SUCCESS)

  		goto err_out;

  	c->rc.size = wc->byte_len;
  	err = p9_parse_header(&c->rc, NULL, NULL, &tag, 1);

  	if (err)
  		goto err_out;
  
  	req = p9_tag_lookup(client, tag);
  	if (!req)
  		goto err_out;

  	/* Check that we have not yet received a reply for this request.
  	 */

  	if (unlikely(req->rc.sdata)) {

  		pr_err("Duplicate reply for request %d", tag);
  		goto err_out;
  	}

  	req->rc.size = c->rc.size;
  	req->rc.sdata = c->rc.sdata;

  	p9_client_cb(client, req, REQ_STATUS_RCVD);

   out:
  	up(&rdma->rq_sem);
  	kfree(c);

  	return;
  
   err_out:

  	p9_debug(P9_DEBUG_ERROR, "req %p err %d status %d
  ",
  			req, err, wc->status);

  	rdma->state = P9_RDMA_FLUSHING;
  	client->status = Disconnected;

  	goto out;

  }
  
  static void

  send_done(struct ib_cq *cq, struct ib_wc *wc)

  {

  	struct p9_client *client = cq->cq_context;
  	struct p9_trans_rdma *rdma = client->trans;
  	struct p9_rdma_context *c =
  		container_of(wc->wr_cqe, struct p9_rdma_context, cqe);

  	ib_dma_unmap_single(rdma->cm_id->device,

  			    c->busa, c->req->tc.size,

  			    DMA_TO_DEVICE);

  	up(&rdma->sq_sem);

  	p9_req_put(c->req);

  	kfree(c);

  }
  
  static void qp_event_handler(struct ib_event *event, void *context)
  {

  	p9_debug(P9_DEBUG_ERROR, "QP event %d context %p
  ",
  		 event->event, context);

  }

  static void rdma_destroy_trans(struct p9_trans_rdma *rdma)
  {
  	if (!rdma)
  		return;

  	if (rdma->qp && !IS_ERR(rdma->qp))
  		ib_destroy_qp(rdma->qp);
  
  	if (rdma->pd && !IS_ERR(rdma->pd))
  		ib_dealloc_pd(rdma->pd);
  
  	if (rdma->cq && !IS_ERR(rdma->cq))

  		ib_free_cq(rdma->cq);

  
  	if (rdma->cm_id && !IS_ERR(rdma->cm_id))
  		rdma_destroy_id(rdma->cm_id);
  
  	kfree(rdma);
  }
  
  static int
  post_recv(struct p9_client *client, struct p9_rdma_context *c)
  {
  	struct p9_trans_rdma *rdma = client->trans;

  	struct ib_recv_wr wr;

  	struct ib_sge sge;
  
  	c->busa = ib_dma_map_single(rdma->cm_id->device,

  				    c->rc.sdata, client->msize,

  				    DMA_FROM_DEVICE);
  	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
  		goto error;

  	c->cqe.done = recv_done;

  	sge.addr = c->busa;
  	sge.length = client->msize;

  	sge.lkey = rdma->pd->local_dma_lkey;

  
  	wr.next = NULL;

  	wr.wr_cqe = &c->cqe;

  	wr.sg_list = &sge;
  	wr.num_sge = 1;

  	return ib_post_recv(rdma->qp, &wr, NULL);

  
   error:

  	p9_debug(P9_DEBUG_ERROR, "EIO
  ");

  	return -EIO;
  }
  
  static int rdma_request(struct p9_client *client, struct p9_req_t *req)
  {
  	struct p9_trans_rdma *rdma = client->trans;

  	struct ib_send_wr wr;

  	struct ib_sge sge;
  	int err = 0;
  	unsigned long flags;
  	struct p9_rdma_context *c = NULL;
  	struct p9_rdma_context *rpl_context = NULL;

  	/* When an error occurs between posting the recv and the send,
  	 * there will be a receive context posted without a pending request.
  	 * Since there is no way to "un-post" it, we remember it and skip
  	 * post_recv() for the next request.
  	 * So here,
  	 * see if we are this `next request' and need to absorb an excess rc.
  	 * If yes, then drop and free our own, and do not recv_post().
  	 **/
  	if (unlikely(atomic_read(&rdma->excess_rc) > 0)) {
  		if ((atomic_sub_return(1, &rdma->excess_rc) >= 0)) {

  			/* Got one! */
  			p9_fcall_fini(&req->rc);
  			req->rc.sdata = NULL;

  			goto dont_need_post_recv;
  		} else {
  			/* We raced and lost. */
  			atomic_inc(&rdma->excess_rc);
  		}
  	}

  	/* Allocate an fcall for the reply */

  	rpl_context = kmalloc(sizeof *rpl_context, GFP_NOFS);

  	if (!rpl_context) {
  		err = -ENOMEM;

  		goto recv_error;

  	}

  	rpl_context->rc.sdata = req->rc.sdata;

  
  	/*
  	 * Post a receive buffer for this request. We need to ensure
  	 * there is a reply buffer available for every outstanding
  	 * request. A flushed request can result in no reply for an
  	 * outstanding request, so we must keep a count to avoid
  	 * overflowing the RQ.
  	 */

  	if (down_interruptible(&rdma->rq_sem)) {
  		err = -EINTR;
  		goto recv_error;
  	}

  
  	err = post_recv(client, rpl_context);
  	if (err) {

  		p9_debug(P9_DEBUG_ERROR, "POST RECV failed: %d
  ", err);

  		goto recv_error;

  	}

  	/* remove posted receive buffer from request structure */

  	req->rc.sdata = NULL;

  dont_need_post_recv:

  	/* Post the request */

  	c = kmalloc(sizeof *c, GFP_NOFS);

  	if (!c) {
  		err = -ENOMEM;

  		goto send_error;

  	}

  	c->req = req;
  
  	c->busa = ib_dma_map_single(rdma->cm_id->device,

  				    c->req->tc.sdata, c->req->tc.size,

  				    DMA_TO_DEVICE);

  	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa)) {
  		err = -EIO;
  		goto send_error;
  	}

  	c->cqe.done = send_done;

  	sge.addr = c->busa;

  	sge.length = c->req->tc.size;

  	sge.lkey = rdma->pd->local_dma_lkey;

  
  	wr.next = NULL;

  	wr.wr_cqe = &c->cqe;

  	wr.opcode = IB_WR_SEND;
  	wr.send_flags = IB_SEND_SIGNALED;
  	wr.sg_list = &sge;
  	wr.num_sge = 1;

  	if (down_interruptible(&rdma->sq_sem)) {
  		err = -EINTR;
  		goto send_error;
  	}

  	/* Mark request as `sent' *before* we actually send it,
  	 * because doing if after could erase the REQ_STATUS_RCVD
  	 * status in case of a very fast reply.
  	 */
  	req->status = REQ_STATUS_SENT;

  	err = ib_post_send(rdma->qp, &wr, NULL);

  	if (err)
  		goto send_error;

  	/* Success */
  	return 0;

   /* Handle errors that happened during or while preparing the send: */
   send_error:

  	req->status = REQ_STATUS_ERROR;

  	kfree(c);

  	p9_debug(P9_DEBUG_ERROR, "Error %d in rdma_request()
  ", err);

  
  	/* Ach.
  	 *  We did recv_post(), but not send. We have one recv_post in excess.
  	 */
  	atomic_inc(&rdma->excess_rc);

  	return err;
  
   /* Handle errors that happened during or while preparing post_recv(): */
   recv_error:

  	kfree(rpl_context);

  	spin_lock_irqsave(&rdma->req_lock, flags);

  	if (err != -EINTR && rdma->state < P9_RDMA_CLOSING) {

  		rdma->state = P9_RDMA_CLOSING;
  		spin_unlock_irqrestore(&rdma->req_lock, flags);
  		rdma_disconnect(rdma->cm_id);
  	} else
  		spin_unlock_irqrestore(&rdma->req_lock, flags);
  	return err;
  }
  
  static void rdma_close(struct p9_client *client)
  {
  	struct p9_trans_rdma *rdma;
  
  	if (!client)
  		return;
  
  	rdma = client->trans;
  	if (!rdma)
  		return;
  
  	client->status = Disconnected;
  	rdma_disconnect(rdma->cm_id);
  	rdma_destroy_trans(rdma);
  }
  
  /**
   * alloc_rdma - Allocate and initialize the rdma transport structure

   * @opts: Mount options structure
   */
  static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts)
  {
  	struct p9_trans_rdma *rdma;
  
  	rdma = kzalloc(sizeof(struct p9_trans_rdma), GFP_KERNEL);
  	if (!rdma)
  		return NULL;

  	rdma->port = opts->port;
  	rdma->privport = opts->privport;

  	rdma->sq_depth = opts->sq_depth;
  	rdma->rq_depth = opts->rq_depth;
  	rdma->timeout = opts->timeout;
  	spin_lock_init(&rdma->req_lock);
  	init_completion(&rdma->cm_done);
  	sema_init(&rdma->sq_sem, rdma->sq_depth);

  	sema_init(&rdma->rq_sem, rdma->rq_depth);

  	atomic_set(&rdma->excess_rc, 0);

  
  	return rdma;
  }

  static int rdma_cancel(struct p9_client *client, struct p9_req_t *req)
  {

  	/* Nothing to do here.
  	 * We will take care of it (if we have to) in rdma_cancelled()
  	 */

  	return 1;
  }

  /* A request has been fully flushed without a reply.
   * That means we have posted one buffer in excess.
   */
  static int rdma_cancelled(struct p9_client *client, struct p9_req_t *req)
  {
  	struct p9_trans_rdma *rdma = client->trans;
  	atomic_inc(&rdma->excess_rc);
  	return 0;
  }

  static int p9_rdma_bind_privport(struct p9_trans_rdma *rdma)
  {
  	struct sockaddr_in cl = {
  		.sin_family = AF_INET,
  		.sin_addr.s_addr = htonl(INADDR_ANY),
  	};
  	int port, err = -EINVAL;
  
  	for (port = P9_DEF_MAX_RESVPORT; port >= P9_DEF_MIN_RESVPORT; port--) {
  		cl.sin_port = htons((ushort)port);
  		err = rdma_bind_addr(rdma->cm_id, (struct sockaddr *)&cl);
  		if (err != -EADDRINUSE)
  			break;
  	}
  	return err;
  }

  /**

   * rdma_create_trans - Transport method for creating a transport instance

   * @client: client instance
   * @addr: IP address string
   * @args: Mount options string
   */
  static int
  rdma_create_trans(struct p9_client *client, const char *addr, char *args)
  {
  	int err;
  	struct p9_rdma_opts opts;
  	struct p9_trans_rdma *rdma;
  	struct rdma_conn_param conn_param;
  	struct ib_qp_init_attr qp_attr;

  	if (addr == NULL)
  		return -EINVAL;

  	/* Parse the transport specific mount options */
  	err = parse_opts(args, &opts);
  	if (err < 0)
  		return err;
  
  	/* Create and initialize the RDMA transport structure */
  	rdma = alloc_rdma(&opts);
  	if (!rdma)
  		return -ENOMEM;
  
  	/* Create the RDMA CM ID */

  	rdma->cm_id = rdma_create_id(&init_net, p9_cm_event_handler, client,
  				     RDMA_PS_TCP, IB_QPT_RC);

  	if (IS_ERR(rdma->cm_id))
  		goto error;

  	/* Associate the client with the transport */
  	client->trans = rdma;

  	/* Bind to a privileged port if we need to */
  	if (opts.privport) {
  		err = p9_rdma_bind_privport(rdma);
  		if (err < 0) {
  			pr_err("%s (%d): problem binding to privport: %d
  ",
  			       __func__, task_pid_nr(current), -err);
  			goto error;
  		}
  	}

  	/* Resolve the server's address */
  	rdma->addr.sin_family = AF_INET;
  	rdma->addr.sin_addr.s_addr = in_aton(addr);
  	rdma->addr.sin_port = htons(opts.port);
  	err = rdma_resolve_addr(rdma->cm_id, NULL,
  				(struct sockaddr *)&rdma->addr,
  				rdma->timeout);
  	if (err)
  		goto error;
  	err = wait_for_completion_interruptible(&rdma->cm_done);
  	if (err || (rdma->state != P9_RDMA_ADDR_RESOLVED))
  		goto error;
  
  	/* Resolve the route to the server */
  	err = rdma_resolve_route(rdma->cm_id, rdma->timeout);
  	if (err)
  		goto error;
  	err = wait_for_completion_interruptible(&rdma->cm_done);
  	if (err || (rdma->state != P9_RDMA_ROUTE_RESOLVED))
  		goto error;

  	/* Create the Completion Queue */

  	rdma->cq = ib_alloc_cq_any(rdma->cm_id->device, client,
  				   opts.sq_depth + opts.rq_depth + 1,
  				   IB_POLL_SOFTIRQ);

  	if (IS_ERR(rdma->cq))
  		goto error;

  
  	/* Create the Protection Domain */

  	rdma->pd = ib_alloc_pd(rdma->cm_id->device, 0);

  	if (IS_ERR(rdma->pd))
  		goto error;

  	/* Create the Queue Pair */
  	memset(&qp_attr, 0, sizeof qp_attr);
  	qp_attr.event_handler = qp_event_handler;
  	qp_attr.qp_context = client;
  	qp_attr.cap.max_send_wr = opts.sq_depth;
  	qp_attr.cap.max_recv_wr = opts.rq_depth;
  	qp_attr.cap.max_send_sge = P9_RDMA_SEND_SGE;
  	qp_attr.cap.max_recv_sge = P9_RDMA_RECV_SGE;
  	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
  	qp_attr.qp_type = IB_QPT_RC;
  	qp_attr.send_cq = rdma->cq;
  	qp_attr.recv_cq = rdma->cq;
  	err = rdma_create_qp(rdma->cm_id, rdma->pd, &qp_attr);
  	if (err)
  		goto error;
  	rdma->qp = rdma->cm_id->qp;
  
  	/* Request a connection */
  	memset(&conn_param, 0, sizeof(conn_param));
  	conn_param.private_data = NULL;
  	conn_param.private_data_len = 0;
  	conn_param.responder_resources = P9_RDMA_IRD;
  	conn_param.initiator_depth = P9_RDMA_ORD;
  	err = rdma_connect(rdma->cm_id, &conn_param);
  	if (err)
  		goto error;
  	err = wait_for_completion_interruptible(&rdma->cm_done);
  	if (err || (rdma->state != P9_RDMA_CONNECTED))
  		goto error;

  	client->status = Connected;
  
  	return 0;
  
  error:
  	rdma_destroy_trans(rdma);
  	return -ENOTCONN;
  }
  
  static struct p9_trans_module p9_rdma_trans = {
  	.name = "rdma",
  	.maxsize = P9_RDMA_MAXSIZE,
  	.def = 0,
  	.owner = THIS_MODULE,
  	.create = rdma_create_trans,
  	.close = rdma_close,
  	.request = rdma_request,
  	.cancel = rdma_cancel,

  	.cancelled = rdma_cancelled,

  	.show_options = p9_rdma_show_options,

  };
  
  /**
   * p9_trans_rdma_init - Register the 9P RDMA transport driver
   */
  static int __init p9_trans_rdma_init(void)
  {
  	v9fs_register_trans(&p9_rdma_trans);
  	return 0;
  }
  
  static void __exit p9_trans_rdma_exit(void)
  {
  	v9fs_unregister_trans(&p9_rdma_trans);
  }
  
  module_init(p9_trans_rdma_init);
  module_exit(p9_trans_rdma_exit);
  
  MODULE_AUTHOR("Tom Tucker <tom@opengridcomputing.com>");
  MODULE_DESCRIPTION("RDMA Transport for 9P");
  MODULE_LICENSE("Dual BSD/GPL");