9p: rdma: RDMA Transport Support for 9P

This patch implements the RDMA transport provider for 9P. It allows
mounts to be performed over iWARP and IB capable network interfaces.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: Latchesar Ionkov <lionkov@lanl.gov>

4 files changed, 723 insertions, 0 deletions

diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index 1f17f3d93727..9fe45b32ce4a 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -206,6 +206,7 @@ int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst);
 struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
 void p9_client_cb(struct p9_client *c, struct p9_req_t *req);
 
+int p9_parse_header(struct p9_fcall *, int32_t *, int8_t *, int16_t *, int);
 int p9stat_read(char *, int, struct p9_wstat *, int);
 void p9stat_free(struct p9_wstat *);
 
diff --git a/net/9p/Kconfig b/net/9p/Kconfig
index ff34c5acc130..c42c0c400bf9 100644
--- a/net/9p/Kconfig
+++ b/net/9p/Kconfig
@@ -20,6 +20,12 @@ config NET_9P_VIRTIO
           This builds support for a transports between
           guest partitions and a host partition.
 
+config NET_9P_RDMA
+        depends on NET_9P && INFINIBAND && EXPERIMENTAL
+        tristate "9P RDMA Transport (Experimental)"
+        help
+          This builds support for a RDMA transport.
+
 config NET_9P_DEBUG
         bool "Debug information"
         depends on NET_9P
diff --git a/net/9p/Makefile b/net/9p/Makefile
index 1041b7bd12e2..198a640d53a6 100644
--- a/net/9p/Makefile
+++ b/net/9p/Makefile
@@ -1,5 +1,6 @@
 obj-$(CONFIG_NET_9P) := 9pnet.o
 obj-$(CONFIG_NET_9P_VIRTIO) += 9pnet_virtio.o
+obj-$(CONFIG_NET_9P_RDMA) += 9pnet_rdma.o
 
 9pnet-objs := \
         mod.o \
@@ -11,3 +12,6 @@ obj-$(CONFIG_NET_9P_VIRTIO) += 9pnet_virtio.o
 
 9pnet_virtio-objs := \
         trans_virtio.o \
+
+9pnet_rdma-objs := \
+        trans_rdma.o \
diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
new file mode 100644
index 000000000000..8d6cc4777aae
--- /dev/null
+++ b/net/9p/trans_rdma.c
@@ -0,0 +1,712 @@
+/*
+ * 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>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to:
+ *  Free Software Foundation
+ *  51 Franklin Street, Fifth Floor
+ *  Boston, MA  02111-1301  USA
+ *
+ */
+
+#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 <net/9p/9p.h>
+#include <net/9p/client.h>
+#include <net/9p/transport.h>
+#include <rdma/ib_verbs.h>
+#include <rdma/rdma_cm.h>
+#include <rdma/ib_verbs.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         (4*4096)        /* Min SGE is 4, so we can
+                                                 * safely advertise a maxsize
+                                                 * of 64k */
+
+#define P9_RDMA_MAX_SGE (P9_RDMA_MAXSIZE >> PAGE_SHIFT)
+/**
+ * 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
+ * @lkey: The local access only memory region key
+ * @timeout: Number of uSecs to wait for connection management events
+ * @sq_depth: The depth of the Send Queue
+ * @sq_sem: Semaphore for the SQ
+ * @rq_depth: The depth of the Receive Queue.
+ * @addr: The remote peer's address
+ * @req_lock: Protects the active request list
+ * @send_wait: Wait list when the SQ fills up
+ * @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;
+        struct ib_mr *dma_mr;
+        u32 lkey;
+        long timeout;
+        int sq_depth;
+        struct semaphore sq_sem;
+        int rq_depth;
+        atomic_t rq_count;
+        struct sockaddr_in addr;
+        spinlock_t req_lock;
+
+        struct completion cm_done;
+};
+
+/**
+ * p9_rdma_context - Keeps track of in-process WR
+ *
+ * @wc_op: The original WR op for when the CQE completes in error.
+ * @busa: Bus address to unmap when the WR completes
+ * @req: Keeps track of requests (send)
+ * @rc: Keepts track of replies (receive)
+ */
+struct p9_rdma_req;
+struct p9_rdma_context {
+        enum ib_wc_opcode wc_op;
+        dma_addr_t busa;
+        union {
+                struct p9_req_t *req;
+                struct p9_fcall *rc;
+        };
+};
+
+/**
+ * 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;
+        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, 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_err, NULL},
+};
+
+/**
+ * parse_options - parse mount options into session structure
+ * @options: options string passed from mount
+ * @opts: 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;
+        int ret;
+
+        opts->port = P9_PORT;
+        opts->sq_depth = P9_RDMA_SQ_DEPTH;
+        opts->rq_depth = P9_RDMA_RQ_DEPTH;
+        opts->timeout = P9_RDMA_TIMEOUT;
+
+        if (!params)
+                return 0;
+
+        options = kstrdup(params, GFP_KERNEL);
+        if (!options) {
+                P9_DPRINTK(P9_DEBUG_ERROR,
+                           "failed to allocate copy of option string\n");
+                return -ENOMEM;
+        }
+
+        while ((p = strsep(&options, ",")) != NULL) {
+                int token;
+                int r;
+                if (!*p)
+                        continue;
+                token = match_token(p, tokens, args);
+                r = match_int(&args[0], &option);
+                if (r < 0) {
+                        P9_DPRINTK(P9_DEBUG_ERROR,
+                                   "integer field, but no integer?\n");
+                        ret = r;
+                        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;
+                default:
+                        continue;
+                }
+        }
+        /* RQ must be at least as large as the SQ */
+        opts->rq_depth = max(opts->rq_depth, opts->sq_depth);
+        kfree(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;
+                if (c)
+                        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
+handle_recv(struct p9_client *client, struct p9_trans_rdma *rdma,
+            struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
+{
+        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 (status != IB_WC_SUCCESS)
+                goto err_out;
+
+        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;
+
+        req->rc = c->rc;
+        p9_client_cb(client, req);
+
+        return;
+
+ err_out:
+        P9_DPRINTK(P9_DEBUG_ERROR, "req %p err %d status %d\n",
+                   req, err, status);
+        rdma->state = P9_RDMA_FLUSHING;
+        client->status = Disconnected;
+        return;
+}
+
+static void
+handle_send(struct p9_client *client, struct p9_trans_rdma *rdma,
+            struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
+{
+        ib_dma_unmap_single(rdma->cm_id->device,
+                            c->busa, c->req->tc->size,
+                            DMA_TO_DEVICE);
+}
+
+static void qp_event_handler(struct ib_event *event, void *context)
+{
+        P9_DPRINTK(P9_DEBUG_ERROR, "QP event %d context %p\n", event->event,
+                                                                context);
+}
+
+static void cq_comp_handler(struct ib_cq *cq, void *cq_context)
+{
+        struct p9_client *client = cq_context;
+        struct p9_trans_rdma *rdma = client->trans;
+        int ret;
+        struct ib_wc wc;
+
+        ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);
+        while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
+                struct p9_rdma_context *c = (void *) (unsigned long) wc.wr_id;
+
+                switch (c->wc_op) {
+                case IB_WC_RECV:
+                        atomic_dec(&rdma->rq_count);
+                        handle_recv(client, rdma, c, wc.status, wc.byte_len);
+                        break;
+
+                case IB_WC_SEND:
+                        handle_send(client, rdma, c, wc.status, wc.byte_len);
+                        up(&rdma->sq_sem);
+                        break;
+
+                default:
+                        printk(KERN_ERR "9prdma: unexpected completion type, "
+                               "c->wc_op=%d, wc.opcode=%d, status=%d\n",
+                               c->wc_op, wc.opcode, wc.status);
+                        break;
+                }
+                kfree(c);
+        }
+}
+
+static void cq_event_handler(struct ib_event *e, void *v)
+{
+        P9_DPRINTK(P9_DEBUG_ERROR, "CQ event %d context %p\n", e->event, v);
+}
+
+static void rdma_destroy_trans(struct p9_trans_rdma *rdma)
+{
+        if (!rdma)
+                return;
+
+        if (rdma->dma_mr && !IS_ERR(rdma->dma_mr))
+                ib_dereg_mr(rdma->dma_mr);
+
+        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_destroy_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, *bad_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;
+
+        sge.addr = c->busa;
+        sge.length = client->msize;
+        sge.lkey = rdma->lkey;
+
+        wr.next = NULL;
+        c->wc_op = IB_WC_RECV;
+        wr.wr_id = (unsigned long) c;
+        wr.sg_list = &sge;
+        wr.num_sge = 1;
+        return ib_post_recv(rdma->qp, &wr, &bad_wr);
+
+ error:
+        P9_DPRINTK(P9_DEBUG_ERROR, "EIO\n");
+        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, *bad_wr;
+        struct ib_sge sge;
+        int err = 0;
+        unsigned long flags;
+        struct p9_rdma_context *c = NULL;
+        struct p9_rdma_context *rpl_context = NULL;
+
+        /* Allocate an fcall for the reply */
+        rpl_context = kmalloc(sizeof *rpl_context, GFP_KERNEL);
+        if (!rpl_context)
+                goto err_close;
+
+        /*
+         * If the request has a buffer, steal it, otherwise
+         * allocate a new one.  Typically, requests should already
+         * have receive buffers allocated and just swap them around
+         */
+        if (!req->rc) {
+                req->rc = kmalloc(sizeof(struct p9_fcall)+client->msize,
+                                                                GFP_KERNEL);
+                if (req->rc) {
+                        req->rc->sdata = (char *) req->rc +
+                                                sizeof(struct p9_fcall);
+                        req->rc->capacity = client->msize;
+                }
+        }
+        rpl_context->rc = req->rc;
+        if (!rpl_context->rc) {
+                kfree(rpl_context);
+                goto err_close;
+        }
+
+        /*
+         * 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 (atomic_inc_return(&rdma->rq_count) <= rdma->rq_depth) {
+                err = post_recv(client, rpl_context);
+                if (err) {
+                        kfree(rpl_context->rc);
+                        kfree(rpl_context);
+                        goto err_close;
+                }
+        } else
+                atomic_dec(&rdma->rq_count);
+
+        /* remove posted receive buffer from request structure */
+        req->rc = NULL;
+
+        /* Post the request */
+        c = kmalloc(sizeof *c, GFP_KERNEL);
+        if (!c)
+                goto err_close;
+        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))
+                goto error;
+
+        sge.addr = c->busa;
+        sge.length = c->req->tc->size;
+        sge.lkey = rdma->lkey;
+
+        wr.next = NULL;
+        c->wc_op = IB_WC_SEND;
+        wr.wr_id = (unsigned long) c;
+        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))
+                goto error;
+
+        return ib_post_send(rdma->qp, &wr, &bad_wr);
+
+ error:
+        P9_DPRINTK(P9_DEBUG_ERROR, "EIO\n");
+        return -EIO;
+
+ err_close:
+        spin_lock_irqsave(&rdma->req_lock, flags);
+        if (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
+ * @msize: MTU
+ * @dotu: Extension attribute
+ * @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->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);
+        atomic_set(&rdma->rq_count, 0);
+
+        return rdma;
+}
+
+/* its not clear to me we can do anything after send has been posted */
+static int rdma_cancel(struct p9_client *client, struct p9_req_t *req)
+{
+        return 1;
+}
+
+/**
+ * trans_create_rdma - Transport method for creating atransport 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;
+        struct ib_device_attr devattr;
+
+        /* 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(p9_cm_event_handler, client, RDMA_PS_TCP);
+        if (IS_ERR(rdma->cm_id))
+                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;
+
+        /* Query the device attributes */
+        err = ib_query_device(rdma->cm_id->device, &devattr);
+        if (err)
+                goto error;
+
+        /* Create the Completion Queue */
+        rdma->cq = ib_create_cq(rdma->cm_id->device, cq_comp_handler,
+                                cq_event_handler, client,
+                                opts.sq_depth + opts.rq_depth + 1, 0);
+        if (IS_ERR(rdma->cq))
+                goto error;
+        ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);
+
+        /* Create the Protection Domain */
+        rdma->pd = ib_alloc_pd(rdma->cm_id->device);
+        if (IS_ERR(rdma->pd))
+                goto error;
+
+        /* Cache the DMA lkey in the transport */
+        rdma->dma_mr = NULL;
+        if (devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
+                rdma->lkey = rdma->cm_id->device->local_dma_lkey;
+        else {
+                rdma->dma_mr = ib_get_dma_mr(rdma->pd, IB_ACCESS_LOCAL_WRITE);
+                if (IS_ERR(rdma->dma_mr))
+                        goto error;
+                rdma->lkey = rdma->dma_mr->lkey;
+        }
+
+        /* 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->trans = rdma;
+        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,
+};
+
+/**
+ * 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");