summaryrefslogtreecommitdiff
path: root/drivers/block/rnbd/rnbd-srv.c
blob: 0fb94843a495f96566ce159639e5d8faf1cbf7ca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * RDMA Network Block Driver
 *
 * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
 * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
 * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
 */
#undef pr_fmt
#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt

#include <linux/module.h>
#include <linux/blkdev.h>

#include "rnbd-srv.h"
#include "rnbd-srv-dev.h"

MODULE_DESCRIPTION("RDMA Network Block Device Server");
MODULE_LICENSE("GPL");

static u16 port_nr = RTRS_PORT;

module_param_named(port_nr, port_nr, ushort, 0444);
MODULE_PARM_DESC(port_nr,
		 "The port number the server is listening on (default: "
		 __stringify(RTRS_PORT)")");

#define DEFAULT_DEV_SEARCH_PATH "/"

static char dev_search_path[PATH_MAX] = DEFAULT_DEV_SEARCH_PATH;

static int dev_search_path_set(const char *val, const struct kernel_param *kp)
{
	const char *p = strrchr(val, '\n') ? : val + strlen(val);

	if (strlen(val) >= sizeof(dev_search_path))
		return -EINVAL;

	snprintf(dev_search_path, sizeof(dev_search_path), "%.*s",
		 (int)(p - val), val);

	pr_info("dev_search_path changed to '%s'\n", dev_search_path);

	return 0;
}

static struct kparam_string dev_search_path_kparam_str = {
	.maxlen	= sizeof(dev_search_path),
	.string	= dev_search_path
};

static const struct kernel_param_ops dev_search_path_ops = {
	.set	= dev_search_path_set,
	.get	= param_get_string,
};

module_param_cb(dev_search_path, &dev_search_path_ops,
		&dev_search_path_kparam_str, 0444);
MODULE_PARM_DESC(dev_search_path,
		 "Sets the dev_search_path. When a device is mapped this path is prepended to the device path from the map device operation.  If %SESSNAME% is specified in a path, then device will be searched in a session namespace. (default: "
		 DEFAULT_DEV_SEARCH_PATH ")");

static DEFINE_MUTEX(sess_lock);
static DEFINE_SPINLOCK(dev_lock);

static LIST_HEAD(sess_list);
static LIST_HEAD(dev_list);

struct rnbd_io_private {
	struct rtrs_srv_op		*id;
	struct rnbd_srv_sess_dev	*sess_dev;
};

static void rnbd_sess_dev_release(struct kref *kref)
{
	struct rnbd_srv_sess_dev *sess_dev;

	sess_dev = container_of(kref, struct rnbd_srv_sess_dev, kref);
	complete(sess_dev->destroy_comp);
}

static inline void rnbd_put_sess_dev(struct rnbd_srv_sess_dev *sess_dev)
{
	kref_put(&sess_dev->kref, rnbd_sess_dev_release);
}

void rnbd_endio(void *priv, int error)
{
	struct rnbd_io_private *rnbd_priv = priv;
	struct rnbd_srv_sess_dev *sess_dev = rnbd_priv->sess_dev;

	rnbd_put_sess_dev(sess_dev);

	rtrs_srv_resp_rdma(rnbd_priv->id, error);

	kfree(priv);
}

static struct rnbd_srv_sess_dev *
rnbd_get_sess_dev(int dev_id, struct rnbd_srv_session *srv_sess)
{
	struct rnbd_srv_sess_dev *sess_dev;
	int ret = 0;

	rcu_read_lock();
	sess_dev = xa_load(&srv_sess->index_idr, dev_id);
	if (likely(sess_dev))
		ret = kref_get_unless_zero(&sess_dev->kref);
	rcu_read_unlock();

	if (!sess_dev || !ret)
		return ERR_PTR(-ENXIO);

	return sess_dev;
}

static int process_rdma(struct rtrs_srv *sess,
			struct rnbd_srv_session *srv_sess,
			struct rtrs_srv_op *id, void *data, u32 datalen,
			const void *usr, size_t usrlen)
{
	const struct rnbd_msg_io *msg = usr;
	struct rnbd_io_private *priv;
	struct rnbd_srv_sess_dev *sess_dev;
	u32 dev_id;
	int err;
	struct rnbd_dev_blk_io *io;
	struct bio *bio;
	short prio;

	priv = kmalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	dev_id = le32_to_cpu(msg->device_id);

	sess_dev = rnbd_get_sess_dev(dev_id, srv_sess);
	if (IS_ERR(sess_dev)) {
		pr_err_ratelimited("Got I/O request on session %s for unknown device id %d\n",
				   srv_sess->sessname, dev_id);
		err = -ENOTCONN;
		goto err;
	}

	priv->sess_dev = sess_dev;
	priv->id = id;

	/* Generate bio with pages pointing to the rdma buffer */
	bio = rnbd_bio_map_kern(data, sess_dev->rnbd_dev->ibd_bio_set, datalen, GFP_KERNEL);
	if (IS_ERR(bio)) {
		rnbd_srv_err(sess_dev, "Failed to generate bio, err: %ld\n", PTR_ERR(bio));
		goto sess_dev_put;
	}

	io = container_of(bio, struct rnbd_dev_blk_io, bio);
	io->dev = sess_dev->rnbd_dev;
	io->priv = priv;

	bio->bi_end_io = rnbd_dev_bi_end_io;
	bio->bi_private = io;
	bio->bi_opf = rnbd_to_bio_flags(le32_to_cpu(msg->rw));
	bio->bi_iter.bi_sector = le64_to_cpu(msg->sector);
	bio->bi_iter.bi_size = le32_to_cpu(msg->bi_size);
	prio = srv_sess->ver < RNBD_PROTO_VER_MAJOR ||
	       usrlen < sizeof(*msg) ? 0 : le16_to_cpu(msg->prio);
	bio_set_prio(bio, prio);
	bio_set_dev(bio, sess_dev->rnbd_dev->bdev);

	submit_bio(bio);

	return 0;

sess_dev_put:
	rnbd_put_sess_dev(sess_dev);
err:
	kfree(priv);
	return err;
}

static void destroy_device(struct rnbd_srv_dev *dev)
{
	WARN_ONCE(!list_empty(&dev->sess_dev_list),
		  "Device %s is being destroyed but still in use!\n",
		  dev->id);

	spin_lock(&dev_lock);
	list_del(&dev->list);
	spin_unlock(&dev_lock);

	mutex_destroy(&dev->lock);
	if (dev->dev_kobj.state_in_sysfs)
		/*
		 * Destroy kobj only if it was really created.
		 */
		rnbd_srv_destroy_dev_sysfs(dev);
	else
		kfree(dev);
}

static void destroy_device_cb(struct kref *kref)
{
	struct rnbd_srv_dev *dev;

	dev = container_of(kref, struct rnbd_srv_dev, kref);

	destroy_device(dev);
}

static void rnbd_put_srv_dev(struct rnbd_srv_dev *dev)
{
	kref_put(&dev->kref, destroy_device_cb);
}

void rnbd_destroy_sess_dev(struct rnbd_srv_sess_dev *sess_dev)
{
	DECLARE_COMPLETION_ONSTACK(dc);

	xa_erase(&sess_dev->sess->index_idr, sess_dev->device_id);
	synchronize_rcu();
	sess_dev->destroy_comp = &dc;
	rnbd_put_sess_dev(sess_dev);
	wait_for_completion(&dc); /* wait for inflights to drop to zero */

	rnbd_dev_close(sess_dev->rnbd_dev);
	list_del(&sess_dev->sess_list);
	mutex_lock(&sess_dev->dev->lock);
	list_del(&sess_dev->dev_list);
	if (sess_dev->open_flags & FMODE_WRITE)
		sess_dev->dev->open_write_cnt--;
	mutex_unlock(&sess_dev->dev->lock);

	rnbd_put_srv_dev(sess_dev->dev);

	rnbd_srv_info(sess_dev, "Device closed\n");
	kfree(sess_dev);
}

static void destroy_sess(struct rnbd_srv_session *srv_sess)
{
	struct rnbd_srv_sess_dev *sess_dev, *tmp;

	if (list_empty(&srv_sess->sess_dev_list))
		goto out;

	mutex_lock(&srv_sess->lock);
	list_for_each_entry_safe(sess_dev, tmp, &srv_sess->sess_dev_list,
				 sess_list)
		rnbd_srv_destroy_dev_session_sysfs(sess_dev);
	mutex_unlock(&srv_sess->lock);

out:
	xa_destroy(&srv_sess->index_idr);
	bioset_exit(&srv_sess->sess_bio_set);

	pr_info("RTRS Session %s disconnected\n", srv_sess->sessname);

	mutex_lock(&sess_lock);
	list_del(&srv_sess->list);
	mutex_unlock(&sess_lock);

	mutex_destroy(&srv_sess->lock);
	kfree(srv_sess);
}

static int create_sess(struct rtrs_srv *rtrs)
{
	struct rnbd_srv_session *srv_sess;
	char sessname[NAME_MAX];
	int err;

	err = rtrs_srv_get_sess_name(rtrs, sessname, sizeof(sessname));
	if (err) {
		pr_err("rtrs_srv_get_sess_name(%s): %d\n", sessname, err);

		return err;
	}
	srv_sess = kzalloc(sizeof(*srv_sess), GFP_KERNEL);
	if (!srv_sess)
		return -ENOMEM;

	srv_sess->queue_depth = rtrs_srv_get_queue_depth(rtrs);
	err = bioset_init(&srv_sess->sess_bio_set, srv_sess->queue_depth,
			  offsetof(struct rnbd_dev_blk_io, bio),
			  BIOSET_NEED_BVECS);
	if (err) {
		pr_err("Allocating srv_session for session %s failed\n",
		       sessname);
		kfree(srv_sess);
		return err;
	}

	xa_init_flags(&srv_sess->index_idr, XA_FLAGS_ALLOC);
	INIT_LIST_HEAD(&srv_sess->sess_dev_list);
	mutex_init(&srv_sess->lock);
	mutex_lock(&sess_lock);
	list_add(&srv_sess->list, &sess_list);
	mutex_unlock(&sess_lock);

	srv_sess->rtrs = rtrs;
	strlcpy(srv_sess->sessname, sessname, sizeof(srv_sess->sessname));

	rtrs_srv_set_sess_priv(rtrs, srv_sess);

	return 0;
}

static int rnbd_srv_link_ev(struct rtrs_srv *rtrs,
			     enum rtrs_srv_link_ev ev, void *priv)
{
	struct rnbd_srv_session *srv_sess = priv;

	switch (ev) {
	case RTRS_SRV_LINK_EV_CONNECTED:
		return create_sess(rtrs);

	case RTRS_SRV_LINK_EV_DISCONNECTED:
		if (WARN_ON_ONCE(!srv_sess))
			return -EINVAL;

		destroy_sess(srv_sess);
		return 0;

	default:
		pr_warn("Received unknown RTRS session event %d from session %s\n",
			ev, srv_sess->sessname);
		return -EINVAL;
	}
}

static int process_msg_close(struct rtrs_srv *rtrs,
			     struct rnbd_srv_session *srv_sess,
			     void *data, size_t datalen, const void *usr,
			     size_t usrlen)
{
	const struct rnbd_msg_close *close_msg = usr;
	struct rnbd_srv_sess_dev *sess_dev;

	sess_dev = rnbd_get_sess_dev(le32_to_cpu(close_msg->device_id),
				      srv_sess);
	if (IS_ERR(sess_dev))
		return 0;

	rnbd_put_sess_dev(sess_dev);
	mutex_lock(&srv_sess->lock);
	rnbd_srv_destroy_dev_session_sysfs(sess_dev);
	mutex_unlock(&srv_sess->lock);
	return 0;
}

static int process_msg_open(struct rtrs_srv *rtrs,
			    struct rnbd_srv_session *srv_sess,
			    const void *msg, size_t len,
			    void *data, size_t datalen);

static int process_msg_sess_info(struct rtrs_srv *rtrs,
				 struct rnbd_srv_session *srv_sess,
				 const void *msg, size_t len,
				 void *data, size_t datalen);

static int rnbd_srv_rdma_ev(struct rtrs_srv *rtrs, void *priv,
			     struct rtrs_srv_op *id, int dir,
			     void *data, size_t datalen, const void *usr,
			     size_t usrlen)
{
	struct rnbd_srv_session *srv_sess = priv;
	const struct rnbd_msg_hdr *hdr = usr;
	int ret = 0;
	u16 type;

	if (WARN_ON_ONCE(!srv_sess))
		return -ENODEV;

	type = le16_to_cpu(hdr->type);

	switch (type) {
	case RNBD_MSG_IO:
		return process_rdma(rtrs, srv_sess, id, data, datalen, usr,
				    usrlen);
	case RNBD_MSG_CLOSE:
		ret = process_msg_close(rtrs, srv_sess, data, datalen,
					usr, usrlen);
		break;
	case RNBD_MSG_OPEN:
		ret = process_msg_open(rtrs, srv_sess, usr, usrlen,
				       data, datalen);
		break;
	case RNBD_MSG_SESS_INFO:
		ret = process_msg_sess_info(rtrs, srv_sess, usr, usrlen,
					    data, datalen);
		break;
	default:
		pr_warn("Received unexpected message type %d with dir %d from session %s\n",
			type, dir, srv_sess->sessname);
		return -EINVAL;
	}

	rtrs_srv_resp_rdma(id, ret);
	return 0;
}

static struct rnbd_srv_sess_dev
*rnbd_sess_dev_alloc(struct rnbd_srv_session *srv_sess)
{
	struct rnbd_srv_sess_dev *sess_dev;
	int error;

	sess_dev = kzalloc(sizeof(*sess_dev), GFP_KERNEL);
	if (!sess_dev)
		return ERR_PTR(-ENOMEM);

	error = xa_alloc(&srv_sess->index_idr, &sess_dev->device_id, sess_dev,
			 xa_limit_32b, GFP_NOWAIT);
	if (error < 0) {
		pr_warn("Allocating idr failed, err: %d\n", error);
		kfree(sess_dev);
		return ERR_PTR(error);
	}

	return sess_dev;
}

static struct rnbd_srv_dev *rnbd_srv_init_srv_dev(const char *id)
{
	struct rnbd_srv_dev *dev;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return ERR_PTR(-ENOMEM);

	strlcpy(dev->id, id, sizeof(dev->id));
	kref_init(&dev->kref);
	INIT_LIST_HEAD(&dev->sess_dev_list);
	mutex_init(&dev->lock);

	return dev;
}

static struct rnbd_srv_dev *
rnbd_srv_find_or_add_srv_dev(struct rnbd_srv_dev *new_dev)
{
	struct rnbd_srv_dev *dev;

	spin_lock(&dev_lock);
	list_for_each_entry(dev, &dev_list, list) {
		if (!strncmp(dev->id, new_dev->id, sizeof(dev->id))) {
			if (!kref_get_unless_zero(&dev->kref))
				/*
				 * We lost the race, device is almost dead.
				 *  Continue traversing to find a valid one.
				 */
				continue;
			spin_unlock(&dev_lock);
			return dev;
		}
	}
	list_add(&new_dev->list, &dev_list);
	spin_unlock(&dev_lock);

	return new_dev;
}

static int rnbd_srv_check_update_open_perm(struct rnbd_srv_dev *srv_dev,
					    struct rnbd_srv_session *srv_sess,
					    enum rnbd_access_mode access_mode)
{
	int ret = -EPERM;

	mutex_lock(&srv_dev->lock);

	switch (access_mode) {
	case RNBD_ACCESS_RO:
		ret = 0;
		break;
	case RNBD_ACCESS_RW:
		if (srv_dev->open_write_cnt == 0)  {
			srv_dev->open_write_cnt++;
			ret = 0;
		} else {
			pr_err("Mapping device '%s' for session %s with RW permissions failed. Device already opened as 'RW' by %d client(s), access mode %s.\n",
			       srv_dev->id, srv_sess->sessname,
			       srv_dev->open_write_cnt,
			       rnbd_access_mode_str(access_mode));
		}
		break;
	case RNBD_ACCESS_MIGRATION:
		if (srv_dev->open_write_cnt < 2) {
			srv_dev->open_write_cnt++;
			ret = 0;
		} else {
			pr_err("Mapping device '%s' for session %s with migration permissions failed. Device already opened as 'RW' by %d client(s), access mode %s.\n",
			       srv_dev->id, srv_sess->sessname,
			       srv_dev->open_write_cnt,
			       rnbd_access_mode_str(access_mode));
		}
		break;
	default:
		pr_err("Received mapping request for device '%s' on session %s with invalid access mode: %d\n",
		       srv_dev->id, srv_sess->sessname, access_mode);
		ret = -EINVAL;
	}

	mutex_unlock(&srv_dev->lock);

	return ret;
}

static struct rnbd_srv_dev *
rnbd_srv_get_or_create_srv_dev(struct rnbd_dev *rnbd_dev,
				struct rnbd_srv_session *srv_sess,
				enum rnbd_access_mode access_mode)
{
	int ret;
	struct rnbd_srv_dev *new_dev, *dev;

	new_dev = rnbd_srv_init_srv_dev(rnbd_dev->name);
	if (IS_ERR(new_dev))
		return new_dev;

	dev = rnbd_srv_find_or_add_srv_dev(new_dev);
	if (dev != new_dev)
		kfree(new_dev);

	ret = rnbd_srv_check_update_open_perm(dev, srv_sess, access_mode);
	if (ret) {
		rnbd_put_srv_dev(dev);
		return ERR_PTR(ret);
	}

	return dev;
}

static void rnbd_srv_fill_msg_open_rsp(struct rnbd_msg_open_rsp *rsp,
					struct rnbd_srv_sess_dev *sess_dev)
{
	struct rnbd_dev *rnbd_dev = sess_dev->rnbd_dev;

	rsp->hdr.type = cpu_to_le16(RNBD_MSG_OPEN_RSP);
	rsp->device_id =
		cpu_to_le32(sess_dev->device_id);
	rsp->nsectors =
		cpu_to_le64(get_capacity(rnbd_dev->bdev->bd_disk));
	rsp->logical_block_size	=
		cpu_to_le16(bdev_logical_block_size(rnbd_dev->bdev));
	rsp->physical_block_size =
		cpu_to_le16(bdev_physical_block_size(rnbd_dev->bdev));
	rsp->max_segments =
		cpu_to_le16(rnbd_dev_get_max_segs(rnbd_dev));
	rsp->max_hw_sectors =
		cpu_to_le32(rnbd_dev_get_max_hw_sects(rnbd_dev));
	rsp->max_write_same_sectors =
		cpu_to_le32(bdev_write_same(rnbd_dev->bdev));
	rsp->max_discard_sectors =
		cpu_to_le32(rnbd_dev_get_max_discard_sects(rnbd_dev));
	rsp->discard_granularity =
		cpu_to_le32(rnbd_dev_get_discard_granularity(rnbd_dev));
	rsp->discard_alignment =
		cpu_to_le32(rnbd_dev_get_discard_alignment(rnbd_dev));
	rsp->secure_discard =
		cpu_to_le16(rnbd_dev_get_secure_discard(rnbd_dev));
	rsp->rotational =
		!blk_queue_nonrot(bdev_get_queue(rnbd_dev->bdev));
}

static struct rnbd_srv_sess_dev *
rnbd_srv_create_set_sess_dev(struct rnbd_srv_session *srv_sess,
			      const struct rnbd_msg_open *open_msg,
			      struct rnbd_dev *rnbd_dev, fmode_t open_flags,
			      struct rnbd_srv_dev *srv_dev)
{
	struct rnbd_srv_sess_dev *sdev = rnbd_sess_dev_alloc(srv_sess);

	if (IS_ERR(sdev))
		return sdev;

	kref_init(&sdev->kref);

	strlcpy(sdev->pathname, open_msg->dev_name, sizeof(sdev->pathname));

	sdev->rnbd_dev		= rnbd_dev;
	sdev->sess		= srv_sess;
	sdev->dev		= srv_dev;
	sdev->open_flags	= open_flags;
	sdev->access_mode	= open_msg->access_mode;

	return sdev;
}

static char *rnbd_srv_get_full_path(struct rnbd_srv_session *srv_sess,
				     const char *dev_name)
{
	char *full_path;
	char *a, *b;

	full_path = kmalloc(PATH_MAX, GFP_KERNEL);
	if (!full_path)
		return ERR_PTR(-ENOMEM);

	/*
	 * Replace %SESSNAME% with a real session name in order to
	 * create device namespace.
	 */
	a = strnstr(dev_search_path, "%SESSNAME%", sizeof(dev_search_path));
	if (a) {
		int len = a - dev_search_path;

		len = snprintf(full_path, PATH_MAX, "%.*s/%s/%s", len,
			       dev_search_path, srv_sess->sessname, dev_name);
		if (len >= PATH_MAX) {
			pr_err("Too long path: %s, %s, %s\n",
			       dev_search_path, srv_sess->sessname, dev_name);
			kfree(full_path);
			return ERR_PTR(-EINVAL);
		}
	} else {
		snprintf(full_path, PATH_MAX, "%s/%s",
			 dev_search_path, dev_name);
	}

	/* eliminitate duplicated slashes */
	a = strchr(full_path, '/');
	b = a;
	while (*b != '\0') {
		if (*b == '/' && *a == '/') {
			b++;
		} else {
			a++;
			*a = *b;
			b++;
		}
	}
	a++;
	*a = '\0';

	return full_path;
}

static int process_msg_sess_info(struct rtrs_srv *rtrs,
				 struct rnbd_srv_session *srv_sess,
				 const void *msg, size_t len,
				 void *data, size_t datalen)
{
	const struct rnbd_msg_sess_info *sess_info_msg = msg;
	struct rnbd_msg_sess_info_rsp *rsp = data;

	srv_sess->ver = min_t(u8, sess_info_msg->ver, RNBD_PROTO_VER_MAJOR);
	pr_debug("Session %s using protocol version %d (client version: %d, server version: %d)\n",
		 srv_sess->sessname, srv_sess->ver,
		 sess_info_msg->ver, RNBD_PROTO_VER_MAJOR);

	rsp->hdr.type = cpu_to_le16(RNBD_MSG_SESS_INFO_RSP);
	rsp->ver = srv_sess->ver;

	return 0;
}

/**
 * find_srv_sess_dev() - a dev is already opened by this name
 * @srv_sess:	the session to search.
 * @dev_name:	string containing the name of the device.
 *
 * Return struct rnbd_srv_sess_dev if srv_sess already opened the dev_name
 * NULL if the session didn't open the device yet.
 */
static struct rnbd_srv_sess_dev *
find_srv_sess_dev(struct rnbd_srv_session *srv_sess, const char *dev_name)
{
	struct rnbd_srv_sess_dev *sess_dev;

	if (list_empty(&srv_sess->sess_dev_list))
		return NULL;

	list_for_each_entry(sess_dev, &srv_sess->sess_dev_list, sess_list)
		if (!strcmp(sess_dev->pathname, dev_name))
			return sess_dev;

	return NULL;
}

static int process_msg_open(struct rtrs_srv *rtrs,
			    struct rnbd_srv_session *srv_sess,
			    const void *msg, size_t len,
			    void *data, size_t datalen)
{
	int ret;
	struct rnbd_srv_dev *srv_dev;
	struct rnbd_srv_sess_dev *srv_sess_dev;
	const struct rnbd_msg_open *open_msg = msg;
	fmode_t open_flags;
	char *full_path;
	struct rnbd_dev *rnbd_dev;
	struct rnbd_msg_open_rsp *rsp = data;

	pr_debug("Open message received: session='%s' path='%s' access_mode=%d\n",
		 srv_sess->sessname, open_msg->dev_name,
		 open_msg->access_mode);
	open_flags = FMODE_READ;
	if (open_msg->access_mode != RNBD_ACCESS_RO)
		open_flags |= FMODE_WRITE;

	mutex_lock(&srv_sess->lock);

	srv_sess_dev = find_srv_sess_dev(srv_sess, open_msg->dev_name);
	if (srv_sess_dev)
		goto fill_response;

	if ((strlen(dev_search_path) + strlen(open_msg->dev_name))
	    >= PATH_MAX) {
		pr_err("Opening device for session %s failed, device path too long. '%s/%s' is longer than PATH_MAX (%d)\n",
		       srv_sess->sessname, dev_search_path, open_msg->dev_name,
		       PATH_MAX);
		ret = -EINVAL;
		goto reject;
	}
	if (strstr(open_msg->dev_name, "..")) {
		pr_err("Opening device for session %s failed, device path %s contains relative path ..\n",
		       srv_sess->sessname, open_msg->dev_name);
		ret = -EINVAL;
		goto reject;
	}
	full_path = rnbd_srv_get_full_path(srv_sess, open_msg->dev_name);
	if (IS_ERR(full_path)) {
		ret = PTR_ERR(full_path);
		pr_err("Opening device '%s' for client %s failed, failed to get device full path, err: %d\n",
		       open_msg->dev_name, srv_sess->sessname, ret);
		goto reject;
	}

	rnbd_dev = rnbd_dev_open(full_path, open_flags,
				 &srv_sess->sess_bio_set);
	if (IS_ERR(rnbd_dev)) {
		pr_err("Opening device '%s' on session %s failed, failed to open the block device, err: %ld\n",
		       full_path, srv_sess->sessname, PTR_ERR(rnbd_dev));
		ret = PTR_ERR(rnbd_dev);
		goto free_path;
	}

	srv_dev = rnbd_srv_get_or_create_srv_dev(rnbd_dev, srv_sess,
						  open_msg->access_mode);
	if (IS_ERR(srv_dev)) {
		pr_err("Opening device '%s' on session %s failed, creating srv_dev failed, err: %ld\n",
		       full_path, srv_sess->sessname, PTR_ERR(srv_dev));
		ret = PTR_ERR(srv_dev);
		goto rnbd_dev_close;
	}

	srv_sess_dev = rnbd_srv_create_set_sess_dev(srv_sess, open_msg,
						     rnbd_dev, open_flags,
						     srv_dev);
	if (IS_ERR(srv_sess_dev)) {
		pr_err("Opening device '%s' on session %s failed, creating sess_dev failed, err: %ld\n",
		       full_path, srv_sess->sessname, PTR_ERR(srv_sess_dev));
		ret = PTR_ERR(srv_sess_dev);
		goto srv_dev_put;
	}

	/* Create the srv_dev sysfs files if they haven't been created yet. The
	 * reason to delay the creation is not to create the sysfs files before
	 * we are sure the device can be opened.
	 */
	mutex_lock(&srv_dev->lock);
	if (!srv_dev->dev_kobj.state_in_sysfs) {
		ret = rnbd_srv_create_dev_sysfs(srv_dev, rnbd_dev->bdev,
						 rnbd_dev->name);
		if (ret) {
			mutex_unlock(&srv_dev->lock);
			rnbd_srv_err(srv_sess_dev,
				      "Opening device failed, failed to create device sysfs files, err: %d\n",
				      ret);
			goto free_srv_sess_dev;
		}
	}

	ret = rnbd_srv_create_dev_session_sysfs(srv_sess_dev);
	if (ret) {
		mutex_unlock(&srv_dev->lock);
		rnbd_srv_err(srv_sess_dev,
			      "Opening device failed, failed to create dev client sysfs files, err: %d\n",
			      ret);
		goto free_srv_sess_dev;
	}

	list_add(&srv_sess_dev->dev_list, &srv_dev->sess_dev_list);
	mutex_unlock(&srv_dev->lock);

	list_add(&srv_sess_dev->sess_list, &srv_sess->sess_dev_list);

	rnbd_srv_info(srv_sess_dev, "Opened device '%s'\n", srv_dev->id);

	kfree(full_path);

fill_response:
	rnbd_srv_fill_msg_open_rsp(rsp, srv_sess_dev);
	mutex_unlock(&srv_sess->lock);
	return 0;

free_srv_sess_dev:
	xa_erase(&srv_sess->index_idr, srv_sess_dev->device_id);
	synchronize_rcu();
	kfree(srv_sess_dev);
srv_dev_put:
	if (open_msg->access_mode != RNBD_ACCESS_RO) {
		mutex_lock(&srv_dev->lock);
		srv_dev->open_write_cnt--;
		mutex_unlock(&srv_dev->lock);
	}
	rnbd_put_srv_dev(srv_dev);
rnbd_dev_close:
	rnbd_dev_close(rnbd_dev);
free_path:
	kfree(full_path);
reject:
	mutex_unlock(&srv_sess->lock);
	return ret;
}

static struct rtrs_srv_ctx *rtrs_ctx;

static struct rtrs_srv_ops rtrs_ops;
static int __init rnbd_srv_init_module(void)
{
	int err;

	BUILD_BUG_ON(sizeof(struct rnbd_msg_hdr) != 4);
	BUILD_BUG_ON(sizeof(struct rnbd_msg_sess_info) != 36);
	BUILD_BUG_ON(sizeof(struct rnbd_msg_sess_info_rsp) != 36);
	BUILD_BUG_ON(sizeof(struct rnbd_msg_open) != 264);
	BUILD_BUG_ON(sizeof(struct rnbd_msg_close) != 8);
	BUILD_BUG_ON(sizeof(struct rnbd_msg_open_rsp) != 56);
	rtrs_ops = (struct rtrs_srv_ops) {
		.rdma_ev = rnbd_srv_rdma_ev,
		.link_ev = rnbd_srv_link_ev,
	};
	rtrs_ctx = rtrs_srv_open(&rtrs_ops, port_nr);
	if (IS_ERR(rtrs_ctx)) {
		err = PTR_ERR(rtrs_ctx);
		pr_err("rtrs_srv_open(), err: %d\n", err);
		return err;
	}

	err = rnbd_srv_create_sysfs_files();
	if (err) {
		pr_err("rnbd_srv_create_sysfs_files(), err: %d\n", err);
		rtrs_srv_close(rtrs_ctx);
		return err;
	}

	return 0;
}

static void __exit rnbd_srv_cleanup_module(void)
{
	rtrs_srv_close(rtrs_ctx);
	WARN_ON(!list_empty(&sess_list));
	rnbd_srv_destroy_sysfs_files();
}

module_init(rnbd_srv_init_module);
module_exit(rnbd_srv_cleanup_module);