xref: /openbmc/linux/net/9p/trans_rdma.c (revision 92ed1a76) 
1 /*
2  * linux/fs/9p/trans_rdma.c
3  *
4  * RDMA transport layer based on the trans_fd.c implementation.
5  *
6  *  Copyright (C) 2008 by Tom Tucker <tom@opengridcomputing.com>
7  *  Copyright (C) 2006 by Russ Cox <rsc@swtch.com>
8  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
9  *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
10  *  Copyright (C) 1997-2002 by Ron Minnich <rminnich@sarnoff.com>
11  *
12  *  This program is free software; you can redistribute it and/or modify
13  *  it under the terms of the GNU General Public License version 2
14  *  as published by the Free Software Foundation.
15  *
16  *  This program is distributed in the hope that it will be useful,
17  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
18  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  *  GNU General Public License for more details.
20  *
21  *  You should have received a copy of the GNU General Public License
22  *  along with this program; if not, write to:
23  *  Free Software Foundation
24  *  51 Franklin Street, Fifth Floor
25  *  Boston, MA  02111-1301  USA
26  *
27  */
28 
29 #include <linux/in.h>
30 #include <linux/module.h>
31 #include <linux/net.h>
32 #include <linux/ipv6.h>
33 #include <linux/kthread.h>
34 #include <linux/errno.h>
35 #include <linux/kernel.h>
36 #include <linux/un.h>
37 #include <linux/uaccess.h>
38 #include <linux/inet.h>
39 #include <linux/idr.h>
40 #include <linux/file.h>
41 #include <linux/parser.h>
42 #include <linux/semaphore.h>
43 #include <linux/slab.h>
44 #include <net/9p/9p.h>
45 #include <net/9p/client.h>
46 #include <net/9p/transport.h>
47 #include <rdma/ib_verbs.h>
48 #include <rdma/rdma_cm.h>
49 
50 #define P9_PORT			5640
51 #define P9_RDMA_SQ_DEPTH	32
52 #define P9_RDMA_RQ_DEPTH	32
53 #define P9_RDMA_SEND_SGE	4
54 #define P9_RDMA_RECV_SGE	4
55 #define P9_RDMA_IRD		0
56 #define P9_RDMA_ORD		0
57 #define P9_RDMA_TIMEOUT		30000		/* 30 seconds */
58 #define P9_RDMA_MAXSIZE		(4*4096)	/* Min SGE is 4, so we can
59 						 * safely advertise a maxsize
60 						 * of 64k */
61 
62 #define P9_RDMA_MAX_SGE (P9_RDMA_MAXSIZE >> PAGE_SHIFT)
63 /**
64  * struct p9_trans_rdma - RDMA transport instance
65  *
66  * @state: tracks the transport state machine for connection setup and tear down
67  * @cm_id: The RDMA CM ID
68  * @pd: Protection Domain pointer
69  * @qp: Queue Pair pointer
70  * @cq: Completion Queue pointer
71  * @dm_mr: DMA Memory Region pointer
72  * @lkey: The local access only memory region key
73  * @timeout: Number of uSecs to wait for connection management events
74  * @sq_depth: The depth of the Send Queue
75  * @sq_sem: Semaphore for the SQ
76  * @rq_depth: The depth of the Receive Queue.
77  * @rq_count: Count of requests in the Receive Queue.
78  * @addr: The remote peer's address
79  * @req_lock: Protects the active request list
80  * @cm_done: Completion event for connection management tracking
81  */
82 struct p9_trans_rdma {
83 	enum {
84 		P9_RDMA_INIT,
85 		P9_RDMA_ADDR_RESOLVED,
86 		P9_RDMA_ROUTE_RESOLVED,
87 		P9_RDMA_CONNECTED,
88 		P9_RDMA_FLUSHING,
89 		P9_RDMA_CLOSING,
90 		P9_RDMA_CLOSED,
91 	} state;
92 	struct rdma_cm_id *cm_id;
93 	struct ib_pd *pd;
94 	struct ib_qp *qp;
95 	struct ib_cq *cq;
96 	struct ib_mr *dma_mr;
97 	u32 lkey;
98 	long timeout;
99 	int sq_depth;
100 	struct semaphore sq_sem;
101 	int rq_depth;
102 	atomic_t rq_count;
103 	struct sockaddr_in addr;
104 	spinlock_t req_lock;
105 
106 	struct completion cm_done;
107 };
108 
109 /**
110  * p9_rdma_context - Keeps track of in-process WR
111  *
112  * @wc_op: The original WR op for when the CQE completes in error.
113  * @busa: Bus address to unmap when the WR completes
114  * @req: Keeps track of requests (send)
115  * @rc: Keepts track of replies (receive)
116  */
117 struct p9_rdma_req;
118 struct p9_rdma_context {
119 	enum ib_wc_opcode wc_op;
120 	dma_addr_t busa;
121 	union {
122 		struct p9_req_t *req;
123 		struct p9_fcall *rc;
124 	};
125 };
126 
127 /**
128  * p9_rdma_opts - Collection of mount options
129  * @port: port of connection
130  * @sq_depth: The requested depth of the SQ. This really doesn't need
131  * to be any deeper than the number of threads used in the client
132  * @rq_depth: The depth of the RQ. Should be greater than or equal to SQ depth
133  * @timeout: Time to wait in msecs for CM events
134  */
135 struct p9_rdma_opts {
136 	short port;
137 	int sq_depth;
138 	int rq_depth;
139 	long timeout;
140 };
141 
142 /*
143  * Option Parsing (code inspired by NFS code)
144  */
145 enum {
146 	/* Options that take integer arguments */
147 	Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout, Opt_err,
148 };
149 
150 static match_table_t tokens = {
151 	{Opt_port, "port=%u"},
152 	{Opt_sq_depth, "sq=%u"},
153 	{Opt_rq_depth, "rq=%u"},
154 	{Opt_timeout, "timeout=%u"},
155 	{Opt_err, NULL},
156 };
157 
158 /**
159  * parse_opts - parse mount options into rdma options structure
160  * @params: options string passed from mount
161  * @opts: rdma transport-specific structure to parse options into
162  *
163  * Returns 0 upon success, -ERRNO upon failure
164  */
165 static int parse_opts(char *params, struct p9_rdma_opts *opts)
166 {
167 	char *p;
168 	substring_t args[MAX_OPT_ARGS];
169 	int option;
170 	char *options, *tmp_options;
171 	int ret;
172 
173 	opts->port = P9_PORT;
174 	opts->sq_depth = P9_RDMA_SQ_DEPTH;
175 	opts->rq_depth = P9_RDMA_RQ_DEPTH;
176 	opts->timeout = P9_RDMA_TIMEOUT;
177 
178 	if (!params)
179 		return 0;
180 
181 	tmp_options = kstrdup(params, GFP_KERNEL);
182 	if (!tmp_options) {
183 		P9_DPRINTK(P9_DEBUG_ERROR,
184 			   "failed to allocate copy of option string\n");
185 		return -ENOMEM;
186 	}
187 	options = tmp_options;
188 
189 	while ((p = strsep(&options, ",")) != NULL) {
190 		int token;
191 		int r;
192 		if (!*p)
193 			continue;
194 		token = match_token(p, tokens, args);
195 		r = match_int(&args[0], &option);
196 		if (r < 0) {
197 			P9_DPRINTK(P9_DEBUG_ERROR,
198 				   "integer field, but no integer?\n");
199 			ret = r;
200 			continue;
201 		}
202 		switch (token) {
203 		case Opt_port:
204 			opts->port = option;
205 			break;
206 		case Opt_sq_depth:
207 			opts->sq_depth = option;
208 			break;
209 		case Opt_rq_depth:
210 			opts->rq_depth = option;
211 			break;
212 		case Opt_timeout:
213 			opts->timeout = option;
214 			break;
215 		default:
216 			continue;
217 		}
218 	}
219 	/* RQ must be at least as large as the SQ */
220 	opts->rq_depth = max(opts->rq_depth, opts->sq_depth);
221 	kfree(tmp_options);
222 	return 0;
223 }
224 
225 static int
226 p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
227 {
228 	struct p9_client *c = id->context;
229 	struct p9_trans_rdma *rdma = c->trans;
230 	switch (event->event) {
231 	case RDMA_CM_EVENT_ADDR_RESOLVED:
232 		BUG_ON(rdma->state != P9_RDMA_INIT);
233 		rdma->state = P9_RDMA_ADDR_RESOLVED;
234 		break;
235 
236 	case RDMA_CM_EVENT_ROUTE_RESOLVED:
237 		BUG_ON(rdma->state != P9_RDMA_ADDR_RESOLVED);
238 		rdma->state = P9_RDMA_ROUTE_RESOLVED;
239 		break;
240 
241 	case RDMA_CM_EVENT_ESTABLISHED:
242 		BUG_ON(rdma->state != P9_RDMA_ROUTE_RESOLVED);
243 		rdma->state = P9_RDMA_CONNECTED;
244 		break;
245 
246 	case RDMA_CM_EVENT_DISCONNECTED:
247 		if (rdma)
248 			rdma->state = P9_RDMA_CLOSED;
249 		if (c)
250 			c->status = Disconnected;
251 		break;
252 
253 	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
254 		break;
255 
256 	case RDMA_CM_EVENT_ADDR_CHANGE:
257 	case RDMA_CM_EVENT_ROUTE_ERROR:
258 	case RDMA_CM_EVENT_DEVICE_REMOVAL:
259 	case RDMA_CM_EVENT_MULTICAST_JOIN:
260 	case RDMA_CM_EVENT_MULTICAST_ERROR:
261 	case RDMA_CM_EVENT_REJECTED:
262 	case RDMA_CM_EVENT_CONNECT_REQUEST:
263 	case RDMA_CM_EVENT_CONNECT_RESPONSE:
264 	case RDMA_CM_EVENT_CONNECT_ERROR:
265 	case RDMA_CM_EVENT_ADDR_ERROR:
266 	case RDMA_CM_EVENT_UNREACHABLE:
267 		c->status = Disconnected;
268 		rdma_disconnect(rdma->cm_id);
269 		break;
270 	default:
271 		BUG();
272 	}
273 	complete(&rdma->cm_done);
274 	return 0;
275 }
276 
277 static void
278 handle_recv(struct p9_client *client, struct p9_trans_rdma *rdma,
279 	    struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
280 {
281 	struct p9_req_t *req;
282 	int err = 0;
283 	int16_t tag;
284 
285 	req = NULL;
286 	ib_dma_unmap_single(rdma->cm_id->device, c->busa, client->msize,
287 							 DMA_FROM_DEVICE);
288 
289 	if (status != IB_WC_SUCCESS)
290 		goto err_out;
291 
292 	err = p9_parse_header(c->rc, NULL, NULL, &tag, 1);
293 	if (err)
294 		goto err_out;
295 
296 	req = p9_tag_lookup(client, tag);
297 	if (!req)
298 		goto err_out;
299 
300 	req->rc = c->rc;
301 	req->status = REQ_STATUS_RCVD;
302 	p9_client_cb(client, req);
303 
304 	return;
305 
306  err_out:
307 	P9_DPRINTK(P9_DEBUG_ERROR, "req %p err %d status %d\n",
308 		   req, err, status);
309 	rdma->state = P9_RDMA_FLUSHING;
310 	client->status = Disconnected;
311 }
312 
313 static void
314 handle_send(struct p9_client *client, struct p9_trans_rdma *rdma,
315 	    struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
316 {
317 	ib_dma_unmap_single(rdma->cm_id->device,
318 			    c->busa, c->req->tc->size,
319 			    DMA_TO_DEVICE);
320 }
321 
322 static void qp_event_handler(struct ib_event *event, void *context)
323 {
324 	P9_DPRINTK(P9_DEBUG_ERROR, "QP event %d context %p\n", event->event,
325 								context);
326 }
327 
328 static void cq_comp_handler(struct ib_cq *cq, void *cq_context)
329 {
330 	struct p9_client *client = cq_context;
331 	struct p9_trans_rdma *rdma = client->trans;
332 	int ret;
333 	struct ib_wc wc;
334 
335 	ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);
336 	while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
337 		struct p9_rdma_context *c = (void *) (unsigned long) wc.wr_id;
338 
339 		switch (c->wc_op) {
340 		case IB_WC_RECV:
341 			atomic_dec(&rdma->rq_count);
342 			handle_recv(client, rdma, c, wc.status, wc.byte_len);
343 			break;
344 
345 		case IB_WC_SEND:
346 			handle_send(client, rdma, c, wc.status, wc.byte_len);
347 			up(&rdma->sq_sem);
348 			break;
349 
350 		default:
351 			printk(KERN_ERR "9prdma: unexpected completion type, "
352 			       "c->wc_op=%d, wc.opcode=%d, status=%d\n",
353 			       c->wc_op, wc.opcode, wc.status);
354 			break;
355 		}
356 		kfree(c);
357 	}
358 }
359 
360 static void cq_event_handler(struct ib_event *e, void *v)
361 {
362 	P9_DPRINTK(P9_DEBUG_ERROR, "CQ event %d context %p\n", e->event, v);
363 }
364 
365 static void rdma_destroy_trans(struct p9_trans_rdma *rdma)
366 {
367 	if (!rdma)
368 		return;
369 
370 	if (rdma->dma_mr && !IS_ERR(rdma->dma_mr))
371 		ib_dereg_mr(rdma->dma_mr);
372 
373 	if (rdma->qp && !IS_ERR(rdma->qp))
374 		ib_destroy_qp(rdma->qp);
375 
376 	if (rdma->pd && !IS_ERR(rdma->pd))
377 		ib_dealloc_pd(rdma->pd);
378 
379 	if (rdma->cq && !IS_ERR(rdma->cq))
380 		ib_destroy_cq(rdma->cq);
381 
382 	if (rdma->cm_id && !IS_ERR(rdma->cm_id))
383 		rdma_destroy_id(rdma->cm_id);
384 
385 	kfree(rdma);
386 }
387 
388 static int
389 post_recv(struct p9_client *client, struct p9_rdma_context *c)
390 {
391 	struct p9_trans_rdma *rdma = client->trans;
392 	struct ib_recv_wr wr, *bad_wr;
393 	struct ib_sge sge;
394 
395 	c->busa = ib_dma_map_single(rdma->cm_id->device,
396 				    c->rc->sdata, client->msize,
397 				    DMA_FROM_DEVICE);
398 	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
399 		goto error;
400 
401 	sge.addr = c->busa;
402 	sge.length = client->msize;
403 	sge.lkey = rdma->lkey;
404 
405 	wr.next = NULL;
406 	c->wc_op = IB_WC_RECV;
407 	wr.wr_id = (unsigned long) c;
408 	wr.sg_list = &sge;
409 	wr.num_sge = 1;
410 	return ib_post_recv(rdma->qp, &wr, &bad_wr);
411 
412  error:
413 	P9_DPRINTK(P9_DEBUG_ERROR, "EIO\n");
414 	return -EIO;
415 }
416 
417 static int rdma_request(struct p9_client *client, struct p9_req_t *req)
418 {
419 	struct p9_trans_rdma *rdma = client->trans;
420 	struct ib_send_wr wr, *bad_wr;
421 	struct ib_sge sge;
422 	int err = 0;
423 	unsigned long flags;
424 	struct p9_rdma_context *c = NULL;
425 	struct p9_rdma_context *rpl_context = NULL;
426 
427 	/* Allocate an fcall for the reply */
428 	rpl_context = kmalloc(sizeof *rpl_context, GFP_KERNEL);
429 	if (!rpl_context) {
430 		err = -ENOMEM;
431 		goto err_close;
432 	}
433 
434 	/*
435 	 * If the request has a buffer, steal it, otherwise
436 	 * allocate a new one.  Typically, requests should already
437 	 * have receive buffers allocated and just swap them around
438 	 */
439 	if (!req->rc) {
440 		req->rc = kmalloc(sizeof(struct p9_fcall)+client->msize,
441 								GFP_KERNEL);
442 		if (req->rc) {
443 			req->rc->sdata = (char *) req->rc +
444 						sizeof(struct p9_fcall);
445 			req->rc->capacity = client->msize;
446 		}
447 	}
448 	rpl_context->rc = req->rc;
449 	if (!rpl_context->rc) {
450 		err = -ENOMEM;
451 		goto err_free2;
452 	}
453 
454 	/*
455 	 * Post a receive buffer for this request. We need to ensure
456 	 * there is a reply buffer available for every outstanding
457 	 * request. A flushed request can result in no reply for an
458 	 * outstanding request, so we must keep a count to avoid
459 	 * overflowing the RQ.
460 	 */
461 	if (atomic_inc_return(&rdma->rq_count) <= rdma->rq_depth) {
462 		err = post_recv(client, rpl_context);
463 		if (err)
464 			goto err_free1;
465 	} else
466 		atomic_dec(&rdma->rq_count);
467 
468 	/* remove posted receive buffer from request structure */
469 	req->rc = NULL;
470 
471 	/* Post the request */
472 	c = kmalloc(sizeof *c, GFP_KERNEL);
473 	if (!c) {
474 		err = -ENOMEM;
475 		goto err_free1;
476 	}
477 	c->req = req;
478 
479 	c->busa = ib_dma_map_single(rdma->cm_id->device,
480 				    c->req->tc->sdata, c->req->tc->size,
481 				    DMA_TO_DEVICE);
482 	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
483 		goto error;
484 
485 	sge.addr = c->busa;
486 	sge.length = c->req->tc->size;
487 	sge.lkey = rdma->lkey;
488 
489 	wr.next = NULL;
490 	c->wc_op = IB_WC_SEND;
491 	wr.wr_id = (unsigned long) c;
492 	wr.opcode = IB_WR_SEND;
493 	wr.send_flags = IB_SEND_SIGNALED;
494 	wr.sg_list = &sge;
495 	wr.num_sge = 1;
496 
497 	if (down_interruptible(&rdma->sq_sem))
498 		goto error;
499 
500 	return ib_post_send(rdma->qp, &wr, &bad_wr);
501 
502  error:
503 	kfree(c);
504 	kfree(rpl_context->rc);
505 	kfree(rpl_context);
506 	P9_DPRINTK(P9_DEBUG_ERROR, "EIO\n");
507 	return -EIO;
508  err_free1:
509 	kfree(rpl_context->rc);
510  err_free2:
511 	kfree(rpl_context);
512  err_close:
513 	spin_lock_irqsave(&rdma->req_lock, flags);
514 	if (rdma->state < P9_RDMA_CLOSING) {
515 		rdma->state = P9_RDMA_CLOSING;
516 		spin_unlock_irqrestore(&rdma->req_lock, flags);
517 		rdma_disconnect(rdma->cm_id);
518 	} else
519 		spin_unlock_irqrestore(&rdma->req_lock, flags);
520 	return err;
521 }
522 
523 static void rdma_close(struct p9_client *client)
524 {
525 	struct p9_trans_rdma *rdma;
526 
527 	if (!client)
528 		return;
529 
530 	rdma = client->trans;
531 	if (!rdma)
532 		return;
533 
534 	client->status = Disconnected;
535 	rdma_disconnect(rdma->cm_id);
536 	rdma_destroy_trans(rdma);
537 }
538 
539 /**
540  * alloc_rdma - Allocate and initialize the rdma transport structure
541  * @opts: Mount options structure
542  */
543 static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts)
544 {
545 	struct p9_trans_rdma *rdma;
546 
547 	rdma = kzalloc(sizeof(struct p9_trans_rdma), GFP_KERNEL);
548 	if (!rdma)
549 		return NULL;
550 
551 	rdma->sq_depth = opts->sq_depth;
552 	rdma->rq_depth = opts->rq_depth;
553 	rdma->timeout = opts->timeout;
554 	spin_lock_init(&rdma->req_lock);
555 	init_completion(&rdma->cm_done);
556 	sema_init(&rdma->sq_sem, rdma->sq_depth);
557 	atomic_set(&rdma->rq_count, 0);
558 
559 	return rdma;
560 }
561 
562 /* its not clear to me we can do anything after send has been posted */
563 static int rdma_cancel(struct p9_client *client, struct p9_req_t *req)
564 {
565 	return 1;
566 }
567 
568 /**
569  * trans_create_rdma - Transport method for creating atransport instance
570  * @client: client instance
571  * @addr: IP address string
572  * @args: Mount options string
573  */
574 static int
575 rdma_create_trans(struct p9_client *client, const char *addr, char *args)
576 {
577 	int err;
578 	struct p9_rdma_opts opts;
579 	struct p9_trans_rdma *rdma;
580 	struct rdma_conn_param conn_param;
581 	struct ib_qp_init_attr qp_attr;
582 	struct ib_device_attr devattr;
583 
584 	/* Parse the transport specific mount options */
585 	err = parse_opts(args, &opts);
586 	if (err < 0)
587 		return err;
588 
589 	/* Create and initialize the RDMA transport structure */
590 	rdma = alloc_rdma(&opts);
591 	if (!rdma)
592 		return -ENOMEM;
593 
594 	/* Create the RDMA CM ID */
595 	rdma->cm_id = rdma_create_id(p9_cm_event_handler, client, RDMA_PS_TCP);
596 	if (IS_ERR(rdma->cm_id))
597 		goto error;
598 
599 	/* Associate the client with the transport */
600 	client->trans = rdma;
601 
602 	/* Resolve the server's address */
603 	rdma->addr.sin_family = AF_INET;
604 	rdma->addr.sin_addr.s_addr = in_aton(addr);
605 	rdma->addr.sin_port = htons(opts.port);
606 	err = rdma_resolve_addr(rdma->cm_id, NULL,
607 				(struct sockaddr *)&rdma->addr,
608 				rdma->timeout);
609 	if (err)
610 		goto error;
611 	err = wait_for_completion_interruptible(&rdma->cm_done);
612 	if (err || (rdma->state != P9_RDMA_ADDR_RESOLVED))
613 		goto error;
614 
615 	/* Resolve the route to the server */
616 	err = rdma_resolve_route(rdma->cm_id, rdma->timeout);
617 	if (err)
618 		goto error;
619 	err = wait_for_completion_interruptible(&rdma->cm_done);
620 	if (err || (rdma->state != P9_RDMA_ROUTE_RESOLVED))
621 		goto error;
622 
623 	/* Query the device attributes */
624 	err = ib_query_device(rdma->cm_id->device, &devattr);
625 	if (err)
626 		goto error;
627 
628 	/* Create the Completion Queue */
629 	rdma->cq = ib_create_cq(rdma->cm_id->device, cq_comp_handler,
630 				cq_event_handler, client,
631 				opts.sq_depth + opts.rq_depth + 1, 0);
632 	if (IS_ERR(rdma->cq))
633 		goto error;
634 	ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);
635 
636 	/* Create the Protection Domain */
637 	rdma->pd = ib_alloc_pd(rdma->cm_id->device);
638 	if (IS_ERR(rdma->pd))
639 		goto error;
640 
641 	/* Cache the DMA lkey in the transport */
642 	rdma->dma_mr = NULL;
643 	if (devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
644 		rdma->lkey = rdma->cm_id->device->local_dma_lkey;
645 	else {
646 		rdma->dma_mr = ib_get_dma_mr(rdma->pd, IB_ACCESS_LOCAL_WRITE);
647 		if (IS_ERR(rdma->dma_mr))
648 			goto error;
649 		rdma->lkey = rdma->dma_mr->lkey;
650 	}
651 
652 	/* Create the Queue Pair */
653 	memset(&qp_attr, 0, sizeof qp_attr);
654 	qp_attr.event_handler = qp_event_handler;
655 	qp_attr.qp_context = client;
656 	qp_attr.cap.max_send_wr = opts.sq_depth;
657 	qp_attr.cap.max_recv_wr = opts.rq_depth;
658 	qp_attr.cap.max_send_sge = P9_RDMA_SEND_SGE;
659 	qp_attr.cap.max_recv_sge = P9_RDMA_RECV_SGE;
660 	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
661 	qp_attr.qp_type = IB_QPT_RC;
662 	qp_attr.send_cq = rdma->cq;
663 	qp_attr.recv_cq = rdma->cq;
664 	err = rdma_create_qp(rdma->cm_id, rdma->pd, &qp_attr);
665 	if (err)
666 		goto error;
667 	rdma->qp = rdma->cm_id->qp;
668 
669 	/* Request a connection */
670 	memset(&conn_param, 0, sizeof(conn_param));
671 	conn_param.private_data = NULL;
672 	conn_param.private_data_len = 0;
673 	conn_param.responder_resources = P9_RDMA_IRD;
674 	conn_param.initiator_depth = P9_RDMA_ORD;
675 	err = rdma_connect(rdma->cm_id, &conn_param);
676 	if (err)
677 		goto error;
678 	err = wait_for_completion_interruptible(&rdma->cm_done);
679 	if (err || (rdma->state != P9_RDMA_CONNECTED))
680 		goto error;
681 
682 	client->status = Connected;
683 
684 	return 0;
685 
686 error:
687 	rdma_destroy_trans(rdma);
688 	return -ENOTCONN;
689 }
690 
691 static struct p9_trans_module p9_rdma_trans = {
692 	.name = "rdma",
693 	.maxsize = P9_RDMA_MAXSIZE,
694 	.def = 0,
695 	.owner = THIS_MODULE,
696 	.create = rdma_create_trans,
697 	.close = rdma_close,
698 	.request = rdma_request,
699 	.cancel = rdma_cancel,
700 };
701 
702 /**
703  * p9_trans_rdma_init - Register the 9P RDMA transport driver
704  */
705 static int __init p9_trans_rdma_init(void)
706 {
707 	v9fs_register_trans(&p9_rdma_trans);
708 	return 0;
709 }
710 
711 static void __exit p9_trans_rdma_exit(void)
712 {
713 	v9fs_unregister_trans(&p9_rdma_trans);
714 }
715 
716 module_init(p9_trans_rdma_init);
717 module_exit(p9_trans_rdma_exit);
718 
719 MODULE_AUTHOR("Tom Tucker <tom@opengridcomputing.com>");
720 MODULE_DESCRIPTION("RDMA Transport for 9P");
721 MODULE_LICENSE("Dual BSD/GPL");
722