xref: /openbmc/linux/net/9p/trans_rdma.c (revision b593bce5) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * linux/fs/9p/trans_rdma.c
4  *
5  * RDMA transport layer based on the trans_fd.c implementation.
6  *
7  *  Copyright (C) 2008 by Tom Tucker <tom@opengridcomputing.com>
8  *  Copyright (C) 2006 by Russ Cox <rsc@swtch.com>
9  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
10  *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
11  *  Copyright (C) 1997-2002 by Ron Minnich <rminnich@sarnoff.com>
12  */
13 
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 
16 #include <linux/in.h>
17 #include <linux/module.h>
18 #include <linux/net.h>
19 #include <linux/ipv6.h>
20 #include <linux/kthread.h>
21 #include <linux/errno.h>
22 #include <linux/kernel.h>
23 #include <linux/un.h>
24 #include <linux/uaccess.h>
25 #include <linux/inet.h>
26 #include <linux/idr.h>
27 #include <linux/file.h>
28 #include <linux/parser.h>
29 #include <linux/semaphore.h>
30 #include <linux/slab.h>
31 #include <linux/seq_file.h>
32 #include <net/9p/9p.h>
33 #include <net/9p/client.h>
34 #include <net/9p/transport.h>
35 #include <rdma/ib_verbs.h>
36 #include <rdma/rdma_cm.h>
37 
38 #define P9_PORT			5640
39 #define P9_RDMA_SQ_DEPTH	32
40 #define P9_RDMA_RQ_DEPTH	32
41 #define P9_RDMA_SEND_SGE	4
42 #define P9_RDMA_RECV_SGE	4
43 #define P9_RDMA_IRD		0
44 #define P9_RDMA_ORD		0
45 #define P9_RDMA_TIMEOUT		30000		/* 30 seconds */
46 #define P9_RDMA_MAXSIZE		(1024*1024)	/* 1MB */
47 
48 /**
49  * struct p9_trans_rdma - RDMA transport instance
50  *
51  * @state: tracks the transport state machine for connection setup and tear down
52  * @cm_id: The RDMA CM ID
53  * @pd: Protection Domain pointer
54  * @qp: Queue Pair pointer
55  * @cq: Completion Queue pointer
56  * @timeout: Number of uSecs to wait for connection management events
57  * @privport: Whether a privileged port may be used
58  * @port: The port to use
59  * @sq_depth: The depth of the Send Queue
60  * @sq_sem: Semaphore for the SQ
61  * @rq_depth: The depth of the Receive Queue.
62  * @rq_sem: Semaphore for the RQ
63  * @excess_rc : Amount of posted Receive Contexts without a pending request.
64  *		See rdma_request()
65  * @addr: The remote peer's address
66  * @req_lock: Protects the active request list
67  * @cm_done: Completion event for connection management tracking
68  */
69 struct p9_trans_rdma {
70 	enum {
71 		P9_RDMA_INIT,
72 		P9_RDMA_ADDR_RESOLVED,
73 		P9_RDMA_ROUTE_RESOLVED,
74 		P9_RDMA_CONNECTED,
75 		P9_RDMA_FLUSHING,
76 		P9_RDMA_CLOSING,
77 		P9_RDMA_CLOSED,
78 	} state;
79 	struct rdma_cm_id *cm_id;
80 	struct ib_pd *pd;
81 	struct ib_qp *qp;
82 	struct ib_cq *cq;
83 	long timeout;
84 	bool privport;
85 	u16 port;
86 	int sq_depth;
87 	struct semaphore sq_sem;
88 	int rq_depth;
89 	struct semaphore rq_sem;
90 	atomic_t excess_rc;
91 	struct sockaddr_in addr;
92 	spinlock_t req_lock;
93 
94 	struct completion cm_done;
95 };
96 
97 /**
98  * p9_rdma_context - Keeps track of in-process WR
99  *
100  * @busa: Bus address to unmap when the WR completes
101  * @req: Keeps track of requests (send)
102  * @rc: Keepts track of replies (receive)
103  */
104 struct p9_rdma_req;
105 struct p9_rdma_context {
106 	struct ib_cqe cqe;
107 	dma_addr_t busa;
108 	union {
109 		struct p9_req_t *req;
110 		struct p9_fcall rc;
111 	};
112 };
113 
114 /**
115  * p9_rdma_opts - Collection of mount options
116  * @port: port of connection
117  * @sq_depth: The requested depth of the SQ. This really doesn't need
118  * to be any deeper than the number of threads used in the client
119  * @rq_depth: The depth of the RQ. Should be greater than or equal to SQ depth
120  * @timeout: Time to wait in msecs for CM events
121  */
122 struct p9_rdma_opts {
123 	short port;
124 	bool privport;
125 	int sq_depth;
126 	int rq_depth;
127 	long timeout;
128 };
129 
130 /*
131  * Option Parsing (code inspired by NFS code)
132  */
133 enum {
134 	/* Options that take integer arguments */
135 	Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout,
136 	/* Options that take no argument */
137 	Opt_privport,
138 	Opt_err,
139 };
140 
141 static match_table_t tokens = {
142 	{Opt_port, "port=%u"},
143 	{Opt_sq_depth, "sq=%u"},
144 	{Opt_rq_depth, "rq=%u"},
145 	{Opt_timeout, "timeout=%u"},
146 	{Opt_privport, "privport"},
147 	{Opt_err, NULL},
148 };
149 
150 static int p9_rdma_show_options(struct seq_file *m, struct p9_client *clnt)
151 {
152 	struct p9_trans_rdma *rdma = clnt->trans;
153 
154 	if (rdma->port != P9_PORT)
155 		seq_printf(m, ",port=%u", rdma->port);
156 	if (rdma->sq_depth != P9_RDMA_SQ_DEPTH)
157 		seq_printf(m, ",sq=%u", rdma->sq_depth);
158 	if (rdma->rq_depth != P9_RDMA_RQ_DEPTH)
159 		seq_printf(m, ",rq=%u", rdma->rq_depth);
160 	if (rdma->timeout != P9_RDMA_TIMEOUT)
161 		seq_printf(m, ",timeout=%lu", rdma->timeout);
162 	if (rdma->privport)
163 		seq_puts(m, ",privport");
164 	return 0;
165 }
166 
167 /**
168  * parse_opts - parse mount options into rdma options structure
169  * @params: options string passed from mount
170  * @opts: rdma transport-specific structure to parse options into
171  *
172  * Returns 0 upon success, -ERRNO upon failure
173  */
174 static int parse_opts(char *params, struct p9_rdma_opts *opts)
175 {
176 	char *p;
177 	substring_t args[MAX_OPT_ARGS];
178 	int option;
179 	char *options, *tmp_options;
180 
181 	opts->port = P9_PORT;
182 	opts->sq_depth = P9_RDMA_SQ_DEPTH;
183 	opts->rq_depth = P9_RDMA_RQ_DEPTH;
184 	opts->timeout = P9_RDMA_TIMEOUT;
185 	opts->privport = false;
186 
187 	if (!params)
188 		return 0;
189 
190 	tmp_options = kstrdup(params, GFP_KERNEL);
191 	if (!tmp_options) {
192 		p9_debug(P9_DEBUG_ERROR,
193 			 "failed to allocate copy of option string\n");
194 		return -ENOMEM;
195 	}
196 	options = tmp_options;
197 
198 	while ((p = strsep(&options, ",")) != NULL) {
199 		int token;
200 		int r;
201 		if (!*p)
202 			continue;
203 		token = match_token(p, tokens, args);
204 		if ((token != Opt_err) && (token != Opt_privport)) {
205 			r = match_int(&args[0], &option);
206 			if (r < 0) {
207 				p9_debug(P9_DEBUG_ERROR,
208 					 "integer field, but no integer?\n");
209 				continue;
210 			}
211 		}
212 		switch (token) {
213 		case Opt_port:
214 			opts->port = option;
215 			break;
216 		case Opt_sq_depth:
217 			opts->sq_depth = option;
218 			break;
219 		case Opt_rq_depth:
220 			opts->rq_depth = option;
221 			break;
222 		case Opt_timeout:
223 			opts->timeout = option;
224 			break;
225 		case Opt_privport:
226 			opts->privport = true;
227 			break;
228 		default:
229 			continue;
230 		}
231 	}
232 	/* RQ must be at least as large as the SQ */
233 	opts->rq_depth = max(opts->rq_depth, opts->sq_depth);
234 	kfree(tmp_options);
235 	return 0;
236 }
237 
238 static int
239 p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
240 {
241 	struct p9_client *c = id->context;
242 	struct p9_trans_rdma *rdma = c->trans;
243 	switch (event->event) {
244 	case RDMA_CM_EVENT_ADDR_RESOLVED:
245 		BUG_ON(rdma->state != P9_RDMA_INIT);
246 		rdma->state = P9_RDMA_ADDR_RESOLVED;
247 		break;
248 
249 	case RDMA_CM_EVENT_ROUTE_RESOLVED:
250 		BUG_ON(rdma->state != P9_RDMA_ADDR_RESOLVED);
251 		rdma->state = P9_RDMA_ROUTE_RESOLVED;
252 		break;
253 
254 	case RDMA_CM_EVENT_ESTABLISHED:
255 		BUG_ON(rdma->state != P9_RDMA_ROUTE_RESOLVED);
256 		rdma->state = P9_RDMA_CONNECTED;
257 		break;
258 
259 	case RDMA_CM_EVENT_DISCONNECTED:
260 		if (rdma)
261 			rdma->state = P9_RDMA_CLOSED;
262 		c->status = Disconnected;
263 		break;
264 
265 	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
266 		break;
267 
268 	case RDMA_CM_EVENT_ADDR_CHANGE:
269 	case RDMA_CM_EVENT_ROUTE_ERROR:
270 	case RDMA_CM_EVENT_DEVICE_REMOVAL:
271 	case RDMA_CM_EVENT_MULTICAST_JOIN:
272 	case RDMA_CM_EVENT_MULTICAST_ERROR:
273 	case RDMA_CM_EVENT_REJECTED:
274 	case RDMA_CM_EVENT_CONNECT_REQUEST:
275 	case RDMA_CM_EVENT_CONNECT_RESPONSE:
276 	case RDMA_CM_EVENT_CONNECT_ERROR:
277 	case RDMA_CM_EVENT_ADDR_ERROR:
278 	case RDMA_CM_EVENT_UNREACHABLE:
279 		c->status = Disconnected;
280 		rdma_disconnect(rdma->cm_id);
281 		break;
282 	default:
283 		BUG();
284 	}
285 	complete(&rdma->cm_done);
286 	return 0;
287 }
288 
289 static void
290 recv_done(struct ib_cq *cq, struct ib_wc *wc)
291 {
292 	struct p9_client *client = cq->cq_context;
293 	struct p9_trans_rdma *rdma = client->trans;
294 	struct p9_rdma_context *c =
295 		container_of(wc->wr_cqe, struct p9_rdma_context, cqe);
296 	struct p9_req_t *req;
297 	int err = 0;
298 	int16_t tag;
299 
300 	req = NULL;
301 	ib_dma_unmap_single(rdma->cm_id->device, c->busa, client->msize,
302 							 DMA_FROM_DEVICE);
303 
304 	if (wc->status != IB_WC_SUCCESS)
305 		goto err_out;
306 
307 	c->rc.size = wc->byte_len;
308 	err = p9_parse_header(&c->rc, NULL, NULL, &tag, 1);
309 	if (err)
310 		goto err_out;
311 
312 	req = p9_tag_lookup(client, tag);
313 	if (!req)
314 		goto err_out;
315 
316 	/* Check that we have not yet received a reply for this request.
317 	 */
318 	if (unlikely(req->rc.sdata)) {
319 		pr_err("Duplicate reply for request %d", tag);
320 		goto err_out;
321 	}
322 
323 	req->rc.size = c->rc.size;
324 	req->rc.sdata = c->rc.sdata;
325 	p9_client_cb(client, req, REQ_STATUS_RCVD);
326 
327  out:
328 	up(&rdma->rq_sem);
329 	kfree(c);
330 	return;
331 
332  err_out:
333 	p9_debug(P9_DEBUG_ERROR, "req %p err %d status %d\n",
334 			req, err, wc->status);
335 	rdma->state = P9_RDMA_FLUSHING;
336 	client->status = Disconnected;
337 	goto out;
338 }
339 
340 static void
341 send_done(struct ib_cq *cq, struct ib_wc *wc)
342 {
343 	struct p9_client *client = cq->cq_context;
344 	struct p9_trans_rdma *rdma = client->trans;
345 	struct p9_rdma_context *c =
346 		container_of(wc->wr_cqe, struct p9_rdma_context, cqe);
347 
348 	ib_dma_unmap_single(rdma->cm_id->device,
349 			    c->busa, c->req->tc.size,
350 			    DMA_TO_DEVICE);
351 	up(&rdma->sq_sem);
352 	p9_req_put(c->req);
353 	kfree(c);
354 }
355 
356 static void qp_event_handler(struct ib_event *event, void *context)
357 {
358 	p9_debug(P9_DEBUG_ERROR, "QP event %d context %p\n",
359 		 event->event, context);
360 }
361 
362 static void rdma_destroy_trans(struct p9_trans_rdma *rdma)
363 {
364 	if (!rdma)
365 		return;
366 
367 	if (rdma->qp && !IS_ERR(rdma->qp))
368 		ib_destroy_qp(rdma->qp);
369 
370 	if (rdma->pd && !IS_ERR(rdma->pd))
371 		ib_dealloc_pd(rdma->pd);
372 
373 	if (rdma->cq && !IS_ERR(rdma->cq))
374 		ib_free_cq(rdma->cq);
375 
376 	if (rdma->cm_id && !IS_ERR(rdma->cm_id))
377 		rdma_destroy_id(rdma->cm_id);
378 
379 	kfree(rdma);
380 }
381 
382 static int
383 post_recv(struct p9_client *client, struct p9_rdma_context *c)
384 {
385 	struct p9_trans_rdma *rdma = client->trans;
386 	struct ib_recv_wr wr;
387 	struct ib_sge sge;
388 
389 	c->busa = ib_dma_map_single(rdma->cm_id->device,
390 				    c->rc.sdata, client->msize,
391 				    DMA_FROM_DEVICE);
392 	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
393 		goto error;
394 
395 	c->cqe.done = recv_done;
396 
397 	sge.addr = c->busa;
398 	sge.length = client->msize;
399 	sge.lkey = rdma->pd->local_dma_lkey;
400 
401 	wr.next = NULL;
402 	wr.wr_cqe = &c->cqe;
403 	wr.sg_list = &sge;
404 	wr.num_sge = 1;
405 	return ib_post_recv(rdma->qp, &wr, NULL);
406 
407  error:
408 	p9_debug(P9_DEBUG_ERROR, "EIO\n");
409 	return -EIO;
410 }
411 
412 static int rdma_request(struct p9_client *client, struct p9_req_t *req)
413 {
414 	struct p9_trans_rdma *rdma = client->trans;
415 	struct ib_send_wr wr;
416 	struct ib_sge sge;
417 	int err = 0;
418 	unsigned long flags;
419 	struct p9_rdma_context *c = NULL;
420 	struct p9_rdma_context *rpl_context = NULL;
421 
422 	/* When an error occurs between posting the recv and the send,
423 	 * there will be a receive context posted without a pending request.
424 	 * Since there is no way to "un-post" it, we remember it and skip
425 	 * post_recv() for the next request.
426 	 * So here,
427 	 * see if we are this `next request' and need to absorb an excess rc.
428 	 * If yes, then drop and free our own, and do not recv_post().
429 	 **/
430 	if (unlikely(atomic_read(&rdma->excess_rc) > 0)) {
431 		if ((atomic_sub_return(1, &rdma->excess_rc) >= 0)) {
432 			/* Got one! */
433 			p9_fcall_fini(&req->rc);
434 			req->rc.sdata = NULL;
435 			goto dont_need_post_recv;
436 		} else {
437 			/* We raced and lost. */
438 			atomic_inc(&rdma->excess_rc);
439 		}
440 	}
441 
442 	/* Allocate an fcall for the reply */
443 	rpl_context = kmalloc(sizeof *rpl_context, GFP_NOFS);
444 	if (!rpl_context) {
445 		err = -ENOMEM;
446 		goto recv_error;
447 	}
448 	rpl_context->rc.sdata = req->rc.sdata;
449 
450 	/*
451 	 * Post a receive buffer for this request. We need to ensure
452 	 * there is a reply buffer available for every outstanding
453 	 * request. A flushed request can result in no reply for an
454 	 * outstanding request, so we must keep a count to avoid
455 	 * overflowing the RQ.
456 	 */
457 	if (down_interruptible(&rdma->rq_sem)) {
458 		err = -EINTR;
459 		goto recv_error;
460 	}
461 
462 	err = post_recv(client, rpl_context);
463 	if (err) {
464 		p9_debug(P9_DEBUG_ERROR, "POST RECV failed: %d\n", err);
465 		goto recv_error;
466 	}
467 	/* remove posted receive buffer from request structure */
468 	req->rc.sdata = NULL;
469 
470 dont_need_post_recv:
471 	/* Post the request */
472 	c = kmalloc(sizeof *c, GFP_NOFS);
473 	if (!c) {
474 		err = -ENOMEM;
475 		goto send_error;
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 		err = -EIO;
484 		goto send_error;
485 	}
486 
487 	c->cqe.done = send_done;
488 
489 	sge.addr = c->busa;
490 	sge.length = c->req->tc.size;
491 	sge.lkey = rdma->pd->local_dma_lkey;
492 
493 	wr.next = NULL;
494 	wr.wr_cqe = &c->cqe;
495 	wr.opcode = IB_WR_SEND;
496 	wr.send_flags = IB_SEND_SIGNALED;
497 	wr.sg_list = &sge;
498 	wr.num_sge = 1;
499 
500 	if (down_interruptible(&rdma->sq_sem)) {
501 		err = -EINTR;
502 		goto send_error;
503 	}
504 
505 	/* Mark request as `sent' *before* we actually send it,
506 	 * because doing if after could erase the REQ_STATUS_RCVD
507 	 * status in case of a very fast reply.
508 	 */
509 	req->status = REQ_STATUS_SENT;
510 	err = ib_post_send(rdma->qp, &wr, NULL);
511 	if (err)
512 		goto send_error;
513 
514 	/* Success */
515 	return 0;
516 
517  /* Handle errors that happened during or while preparing the send: */
518  send_error:
519 	req->status = REQ_STATUS_ERROR;
520 	kfree(c);
521 	p9_debug(P9_DEBUG_ERROR, "Error %d in rdma_request()\n", err);
522 
523 	/* Ach.
524 	 *  We did recv_post(), but not send. We have one recv_post in excess.
525 	 */
526 	atomic_inc(&rdma->excess_rc);
527 	return err;
528 
529  /* Handle errors that happened during or while preparing post_recv(): */
530  recv_error:
531 	kfree(rpl_context);
532 	spin_lock_irqsave(&rdma->req_lock, flags);
533 	if (err != -EINTR && rdma->state < P9_RDMA_CLOSING) {
534 		rdma->state = P9_RDMA_CLOSING;
535 		spin_unlock_irqrestore(&rdma->req_lock, flags);
536 		rdma_disconnect(rdma->cm_id);
537 	} else
538 		spin_unlock_irqrestore(&rdma->req_lock, flags);
539 	return err;
540 }
541 
542 static void rdma_close(struct p9_client *client)
543 {
544 	struct p9_trans_rdma *rdma;
545 
546 	if (!client)
547 		return;
548 
549 	rdma = client->trans;
550 	if (!rdma)
551 		return;
552 
553 	client->status = Disconnected;
554 	rdma_disconnect(rdma->cm_id);
555 	rdma_destroy_trans(rdma);
556 }
557 
558 /**
559  * alloc_rdma - Allocate and initialize the rdma transport structure
560  * @opts: Mount options structure
561  */
562 static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts)
563 {
564 	struct p9_trans_rdma *rdma;
565 
566 	rdma = kzalloc(sizeof(struct p9_trans_rdma), GFP_KERNEL);
567 	if (!rdma)
568 		return NULL;
569 
570 	rdma->port = opts->port;
571 	rdma->privport = opts->privport;
572 	rdma->sq_depth = opts->sq_depth;
573 	rdma->rq_depth = opts->rq_depth;
574 	rdma->timeout = opts->timeout;
575 	spin_lock_init(&rdma->req_lock);
576 	init_completion(&rdma->cm_done);
577 	sema_init(&rdma->sq_sem, rdma->sq_depth);
578 	sema_init(&rdma->rq_sem, rdma->rq_depth);
579 	atomic_set(&rdma->excess_rc, 0);
580 
581 	return rdma;
582 }
583 
584 static int rdma_cancel(struct p9_client *client, struct p9_req_t *req)
585 {
586 	/* Nothing to do here.
587 	 * We will take care of it (if we have to) in rdma_cancelled()
588 	 */
589 	return 1;
590 }
591 
592 /* A request has been fully flushed without a reply.
593  * That means we have posted one buffer in excess.
594  */
595 static int rdma_cancelled(struct p9_client *client, struct p9_req_t *req)
596 {
597 	struct p9_trans_rdma *rdma = client->trans;
598 	atomic_inc(&rdma->excess_rc);
599 	return 0;
600 }
601 
602 static int p9_rdma_bind_privport(struct p9_trans_rdma *rdma)
603 {
604 	struct sockaddr_in cl = {
605 		.sin_family = AF_INET,
606 		.sin_addr.s_addr = htonl(INADDR_ANY),
607 	};
608 	int port, err = -EINVAL;
609 
610 	for (port = P9_DEF_MAX_RESVPORT; port >= P9_DEF_MIN_RESVPORT; port--) {
611 		cl.sin_port = htons((ushort)port);
612 		err = rdma_bind_addr(rdma->cm_id, (struct sockaddr *)&cl);
613 		if (err != -EADDRINUSE)
614 			break;
615 	}
616 	return err;
617 }
618 
619 /**
620  * rdma_create_trans - Transport method for creating a transport instance
621  * @client: client instance
622  * @addr: IP address string
623  * @args: Mount options string
624  */
625 static int
626 rdma_create_trans(struct p9_client *client, const char *addr, char *args)
627 {
628 	int err;
629 	struct p9_rdma_opts opts;
630 	struct p9_trans_rdma *rdma;
631 	struct rdma_conn_param conn_param;
632 	struct ib_qp_init_attr qp_attr;
633 
634 	if (addr == NULL)
635 		return -EINVAL;
636 
637 	/* Parse the transport specific mount options */
638 	err = parse_opts(args, &opts);
639 	if (err < 0)
640 		return err;
641 
642 	/* Create and initialize the RDMA transport structure */
643 	rdma = alloc_rdma(&opts);
644 	if (!rdma)
645 		return -ENOMEM;
646 
647 	/* Create the RDMA CM ID */
648 	rdma->cm_id = rdma_create_id(&init_net, p9_cm_event_handler, client,
649 				     RDMA_PS_TCP, IB_QPT_RC);
650 	if (IS_ERR(rdma->cm_id))
651 		goto error;
652 
653 	/* Associate the client with the transport */
654 	client->trans = rdma;
655 
656 	/* Bind to a privileged port if we need to */
657 	if (opts.privport) {
658 		err = p9_rdma_bind_privport(rdma);
659 		if (err < 0) {
660 			pr_err("%s (%d): problem binding to privport: %d\n",
661 			       __func__, task_pid_nr(current), -err);
662 			goto error;
663 		}
664 	}
665 
666 	/* Resolve the server's address */
667 	rdma->addr.sin_family = AF_INET;
668 	rdma->addr.sin_addr.s_addr = in_aton(addr);
669 	rdma->addr.sin_port = htons(opts.port);
670 	err = rdma_resolve_addr(rdma->cm_id, NULL,
671 				(struct sockaddr *)&rdma->addr,
672 				rdma->timeout);
673 	if (err)
674 		goto error;
675 	err = wait_for_completion_interruptible(&rdma->cm_done);
676 	if (err || (rdma->state != P9_RDMA_ADDR_RESOLVED))
677 		goto error;
678 
679 	/* Resolve the route to the server */
680 	err = rdma_resolve_route(rdma->cm_id, rdma->timeout);
681 	if (err)
682 		goto error;
683 	err = wait_for_completion_interruptible(&rdma->cm_done);
684 	if (err || (rdma->state != P9_RDMA_ROUTE_RESOLVED))
685 		goto error;
686 
687 	/* Create the Completion Queue */
688 	rdma->cq = ib_alloc_cq(rdma->cm_id->device, client,
689 			opts.sq_depth + opts.rq_depth + 1,
690 			0, IB_POLL_SOFTIRQ);
691 	if (IS_ERR(rdma->cq))
692 		goto error;
693 
694 	/* Create the Protection Domain */
695 	rdma->pd = ib_alloc_pd(rdma->cm_id->device, 0);
696 	if (IS_ERR(rdma->pd))
697 		goto error;
698 
699 	/* Create the Queue Pair */
700 	memset(&qp_attr, 0, sizeof qp_attr);
701 	qp_attr.event_handler = qp_event_handler;
702 	qp_attr.qp_context = client;
703 	qp_attr.cap.max_send_wr = opts.sq_depth;
704 	qp_attr.cap.max_recv_wr = opts.rq_depth;
705 	qp_attr.cap.max_send_sge = P9_RDMA_SEND_SGE;
706 	qp_attr.cap.max_recv_sge = P9_RDMA_RECV_SGE;
707 	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
708 	qp_attr.qp_type = IB_QPT_RC;
709 	qp_attr.send_cq = rdma->cq;
710 	qp_attr.recv_cq = rdma->cq;
711 	err = rdma_create_qp(rdma->cm_id, rdma->pd, &qp_attr);
712 	if (err)
713 		goto error;
714 	rdma->qp = rdma->cm_id->qp;
715 
716 	/* Request a connection */
717 	memset(&conn_param, 0, sizeof(conn_param));
718 	conn_param.private_data = NULL;
719 	conn_param.private_data_len = 0;
720 	conn_param.responder_resources = P9_RDMA_IRD;
721 	conn_param.initiator_depth = P9_RDMA_ORD;
722 	err = rdma_connect(rdma->cm_id, &conn_param);
723 	if (err)
724 		goto error;
725 	err = wait_for_completion_interruptible(&rdma->cm_done);
726 	if (err || (rdma->state != P9_RDMA_CONNECTED))
727 		goto error;
728 
729 	client->status = Connected;
730 
731 	return 0;
732 
733 error:
734 	rdma_destroy_trans(rdma);
735 	return -ENOTCONN;
736 }
737 
738 static struct p9_trans_module p9_rdma_trans = {
739 	.name = "rdma",
740 	.maxsize = P9_RDMA_MAXSIZE,
741 	.def = 0,
742 	.owner = THIS_MODULE,
743 	.create = rdma_create_trans,
744 	.close = rdma_close,
745 	.request = rdma_request,
746 	.cancel = rdma_cancel,
747 	.cancelled = rdma_cancelled,
748 	.show_options = p9_rdma_show_options,
749 };
750 
751 /**
752  * p9_trans_rdma_init - Register the 9P RDMA transport driver
753  */
754 static int __init p9_trans_rdma_init(void)
755 {
756 	v9fs_register_trans(&p9_rdma_trans);
757 	return 0;
758 }
759 
760 static void __exit p9_trans_rdma_exit(void)
761 {
762 	v9fs_unregister_trans(&p9_rdma_trans);
763 }
764 
765 module_init(p9_trans_rdma_init);
766 module_exit(p9_trans_rdma_exit);
767 
768 MODULE_AUTHOR("Tom Tucker <tom@opengridcomputing.com>");
769 MODULE_DESCRIPTION("RDMA Transport for 9P");
770 MODULE_LICENSE("Dual BSD/GPL");
771