1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * RDMA Network Block Driver
4  *
5  * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
6  * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
7  * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
8  */
9 
10 #undef pr_fmt
11 #define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
12 
13 #include <linux/types.h>
14 #include <linux/ctype.h>
15 #include <linux/parser.h>
16 #include <linux/module.h>
17 #include <linux/in6.h>
18 #include <linux/fs.h>
19 #include <linux/uaccess.h>
20 #include <linux/device.h>
21 #include <rdma/ib.h>
22 #include <rdma/rdma_cm.h>
23 
24 #include "rnbd-clt.h"
25 
26 static struct device *rnbd_dev;
27 static struct class *rnbd_dev_class;
28 static struct kobject *rnbd_devs_kobj;
29 
30 enum {
31 	RNBD_OPT_ERR		= 0,
32 	RNBD_OPT_DEST_PORT	= 1 << 0,
33 	RNBD_OPT_PATH		= 1 << 1,
34 	RNBD_OPT_DEV_PATH	= 1 << 2,
35 	RNBD_OPT_ACCESS_MODE	= 1 << 3,
36 	RNBD_OPT_SESSNAME	= 1 << 6,
37 	RNBD_OPT_NR_POLL_QUEUES	= 1 << 7,
38 };
39 
40 static const unsigned int rnbd_opt_mandatory[] = {
41 	RNBD_OPT_DEV_PATH,
42 	RNBD_OPT_SESSNAME,
43 };
44 
45 static const match_table_t rnbd_opt_tokens = {
46 	{RNBD_OPT_PATH,			"path=%s"		},
47 	{RNBD_OPT_DEV_PATH,		"device_path=%s"	},
48 	{RNBD_OPT_DEST_PORT,		"dest_port=%d"		},
49 	{RNBD_OPT_ACCESS_MODE,		"access_mode=%s"	},
50 	{RNBD_OPT_SESSNAME,		"sessname=%s"		},
51 	{RNBD_OPT_NR_POLL_QUEUES,	"nr_poll_queues=%d"	},
52 	{RNBD_OPT_ERR,			NULL			},
53 };
54 
55 struct rnbd_map_options {
56 	char *sessname;
57 	struct rtrs_addr *paths;
58 	size_t *path_cnt;
59 	char *pathname;
60 	u16 *dest_port;
61 	enum rnbd_access_mode *access_mode;
62 	u32 *nr_poll_queues;
63 };
64 
65 static int rnbd_clt_parse_map_options(const char *buf, size_t max_path_cnt,
66 				       struct rnbd_map_options *opt)
67 {
68 	char *options, *sep_opt;
69 	char *p;
70 	substring_t args[MAX_OPT_ARGS];
71 	int opt_mask = 0;
72 	int token;
73 	int ret = -EINVAL;
74 	int i, dest_port, nr_poll_queues;
75 	int p_cnt = 0;
76 
77 	options = kstrdup(buf, GFP_KERNEL);
78 	if (!options)
79 		return -ENOMEM;
80 
81 	sep_opt = strstrip(options);
82 	while ((p = strsep(&sep_opt, " ")) != NULL) {
83 		if (!*p)
84 			continue;
85 
86 		token = match_token(p, rnbd_opt_tokens, args);
87 		opt_mask |= token;
88 
89 		switch (token) {
90 		case RNBD_OPT_SESSNAME:
91 			p = match_strdup(args);
92 			if (!p) {
93 				ret = -ENOMEM;
94 				goto out;
95 			}
96 			if (strlen(p) > NAME_MAX) {
97 				pr_err("map_device: sessname too long\n");
98 				ret = -EINVAL;
99 				kfree(p);
100 				goto out;
101 			}
102 			strscpy(opt->sessname, p, NAME_MAX);
103 			kfree(p);
104 			break;
105 
106 		case RNBD_OPT_PATH:
107 			if (p_cnt >= max_path_cnt) {
108 				pr_err("map_device: too many (> %zu) paths provided\n",
109 				       max_path_cnt);
110 				ret = -ENOMEM;
111 				goto out;
112 			}
113 			p = match_strdup(args);
114 			if (!p) {
115 				ret = -ENOMEM;
116 				goto out;
117 			}
118 
119 			ret = rtrs_addr_to_sockaddr(p, strlen(p),
120 						    *opt->dest_port,
121 						    &opt->paths[p_cnt]);
122 			if (ret) {
123 				pr_err("Can't parse path %s: %d\n", p, ret);
124 				kfree(p);
125 				goto out;
126 			}
127 
128 			p_cnt++;
129 
130 			kfree(p);
131 			break;
132 
133 		case RNBD_OPT_DEV_PATH:
134 			p = match_strdup(args);
135 			if (!p) {
136 				ret = -ENOMEM;
137 				goto out;
138 			}
139 			if (strlen(p) > NAME_MAX) {
140 				pr_err("map_device: Device path too long\n");
141 				ret = -EINVAL;
142 				kfree(p);
143 				goto out;
144 			}
145 			strscpy(opt->pathname, p, NAME_MAX);
146 			kfree(p);
147 			break;
148 
149 		case RNBD_OPT_DEST_PORT:
150 			if (match_int(args, &dest_port) || dest_port < 0 ||
151 			    dest_port > 65535) {
152 				pr_err("bad destination port number parameter '%d'\n",
153 				       dest_port);
154 				ret = -EINVAL;
155 				goto out;
156 			}
157 			*opt->dest_port = dest_port;
158 			break;
159 
160 		case RNBD_OPT_ACCESS_MODE:
161 			p = match_strdup(args);
162 			if (!p) {
163 				ret = -ENOMEM;
164 				goto out;
165 			}
166 
167 			if (!strcmp(p, "ro")) {
168 				*opt->access_mode = RNBD_ACCESS_RO;
169 			} else if (!strcmp(p, "rw")) {
170 				*opt->access_mode = RNBD_ACCESS_RW;
171 			} else if (!strcmp(p, "migration")) {
172 				*opt->access_mode = RNBD_ACCESS_MIGRATION;
173 			} else {
174 				pr_err("map_device: Invalid access_mode: '%s'\n",
175 				       p);
176 				ret = -EINVAL;
177 				kfree(p);
178 				goto out;
179 			}
180 
181 			kfree(p);
182 			break;
183 
184 		case RNBD_OPT_NR_POLL_QUEUES:
185 			if (match_int(args, &nr_poll_queues) || nr_poll_queues < -1 ||
186 			    nr_poll_queues > (int)nr_cpu_ids) {
187 				pr_err("bad nr_poll_queues parameter '%d'\n",
188 				       nr_poll_queues);
189 				ret = -EINVAL;
190 				goto out;
191 			}
192 			if (nr_poll_queues == -1)
193 				nr_poll_queues = nr_cpu_ids;
194 			*opt->nr_poll_queues = nr_poll_queues;
195 			break;
196 
197 		default:
198 			pr_err("map_device: Unknown parameter or missing value '%s'\n",
199 			       p);
200 			ret = -EINVAL;
201 			goto out;
202 		}
203 	}
204 
205 	for (i = 0; i < ARRAY_SIZE(rnbd_opt_mandatory); i++) {
206 		if ((opt_mask & rnbd_opt_mandatory[i])) {
207 			ret = 0;
208 		} else {
209 			pr_err("map_device: Parameters missing\n");
210 			ret = -EINVAL;
211 			break;
212 		}
213 	}
214 
215 out:
216 	*opt->path_cnt = p_cnt;
217 	kfree(options);
218 	return ret;
219 }
220 
221 static ssize_t state_show(struct kobject *kobj,
222 			  struct kobj_attribute *attr, char *page)
223 {
224 	struct rnbd_clt_dev *dev;
225 
226 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
227 
228 	switch (dev->dev_state) {
229 	case DEV_STATE_INIT:
230 		return sysfs_emit(page, "init\n");
231 	case DEV_STATE_MAPPED:
232 		/* TODO fix cli tool before changing to proper state */
233 		return sysfs_emit(page, "open\n");
234 	case DEV_STATE_MAPPED_DISCONNECTED:
235 		/* TODO fix cli tool before changing to proper state */
236 		return sysfs_emit(page, "closed\n");
237 	case DEV_STATE_UNMAPPED:
238 		return sysfs_emit(page, "unmapped\n");
239 	default:
240 		return sysfs_emit(page, "unknown\n");
241 	}
242 }
243 
244 static struct kobj_attribute rnbd_clt_state_attr = __ATTR_RO(state);
245 
246 static ssize_t nr_poll_queues_show(struct kobject *kobj,
247 				   struct kobj_attribute *attr, char *page)
248 {
249 	struct rnbd_clt_dev *dev;
250 
251 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
252 
253 	return sysfs_emit(page, "%d\n", dev->nr_poll_queues);
254 }
255 
256 static struct kobj_attribute rnbd_clt_nr_poll_queues =
257 	__ATTR_RO(nr_poll_queues);
258 
259 static ssize_t mapping_path_show(struct kobject *kobj,
260 				 struct kobj_attribute *attr, char *page)
261 {
262 	struct rnbd_clt_dev *dev;
263 
264 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
265 
266 	return sysfs_emit(page, "%s\n", dev->pathname);
267 }
268 
269 static struct kobj_attribute rnbd_clt_mapping_path_attr =
270 	__ATTR_RO(mapping_path);
271 
272 static ssize_t access_mode_show(struct kobject *kobj,
273 				struct kobj_attribute *attr, char *page)
274 {
275 	struct rnbd_clt_dev *dev;
276 
277 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
278 
279 	return sysfs_emit(page, "%s\n", rnbd_access_mode_str(dev->access_mode));
280 }
281 
282 static struct kobj_attribute rnbd_clt_access_mode =
283 	__ATTR_RO(access_mode);
284 
285 static ssize_t rnbd_clt_unmap_dev_show(struct kobject *kobj,
286 					struct kobj_attribute *attr, char *page)
287 {
288 	return sysfs_emit(page, "Usage: echo <normal|force> > %s\n",
289 			  attr->attr.name);
290 }
291 
292 static ssize_t rnbd_clt_unmap_dev_store(struct kobject *kobj,
293 					 struct kobj_attribute *attr,
294 					 const char *buf, size_t count)
295 {
296 	struct rnbd_clt_dev *dev;
297 	char *opt, *options;
298 	bool force;
299 	int err;
300 
301 	opt = kstrdup(buf, GFP_KERNEL);
302 	if (!opt)
303 		return -ENOMEM;
304 
305 	options = strstrip(opt);
306 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
307 	if (sysfs_streq(options, "normal")) {
308 		force = false;
309 	} else if (sysfs_streq(options, "force")) {
310 		force = true;
311 	} else {
312 		rnbd_clt_err(dev,
313 			      "unmap_device: Invalid value: %s\n",
314 			      options);
315 		err = -EINVAL;
316 		goto out;
317 	}
318 
319 	rnbd_clt_info(dev, "Unmapping device, option: %s.\n",
320 		       force ? "force" : "normal");
321 
322 	/*
323 	 * We take explicit module reference only for one reason: do not
324 	 * race with lockless rnbd_destroy_sessions().
325 	 */
326 	if (!try_module_get(THIS_MODULE)) {
327 		err = -ENODEV;
328 		goto out;
329 	}
330 	err = rnbd_clt_unmap_device(dev, force, &attr->attr);
331 	if (err) {
332 		if (err != -EALREADY)
333 			rnbd_clt_err(dev, "unmap_device: %d\n",  err);
334 		goto module_put;
335 	}
336 
337 	/*
338 	 * Here device can be vanished!
339 	 */
340 
341 	err = count;
342 
343 module_put:
344 	module_put(THIS_MODULE);
345 out:
346 	kfree(opt);
347 
348 	return err;
349 }
350 
351 static struct kobj_attribute rnbd_clt_unmap_device_attr =
352 	__ATTR(unmap_device, 0644, rnbd_clt_unmap_dev_show,
353 	       rnbd_clt_unmap_dev_store);
354 
355 static ssize_t rnbd_clt_resize_dev_show(struct kobject *kobj,
356 					 struct kobj_attribute *attr,
357 					 char *page)
358 {
359 	return sysfs_emit(page, "Usage: echo <new size in sectors> > %s\n",
360 			  attr->attr.name);
361 }
362 
363 static ssize_t rnbd_clt_resize_dev_store(struct kobject *kobj,
364 					  struct kobj_attribute *attr,
365 					  const char *buf, size_t count)
366 {
367 	int ret;
368 	unsigned long sectors;
369 	struct rnbd_clt_dev *dev;
370 
371 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
372 
373 	ret = kstrtoul(buf, 0, &sectors);
374 	if (ret)
375 		return ret;
376 
377 	ret = rnbd_clt_resize_disk(dev, (size_t)sectors);
378 	if (ret)
379 		return ret;
380 
381 	return count;
382 }
383 
384 static struct kobj_attribute rnbd_clt_resize_dev_attr =
385 	__ATTR(resize, 0644, rnbd_clt_resize_dev_show,
386 	       rnbd_clt_resize_dev_store);
387 
388 static ssize_t rnbd_clt_remap_dev_show(struct kobject *kobj,
389 					struct kobj_attribute *attr, char *page)
390 {
391 	return sysfs_emit(page, "Usage: echo <1> > %s\n", attr->attr.name);
392 }
393 
394 static ssize_t rnbd_clt_remap_dev_store(struct kobject *kobj,
395 					 struct kobj_attribute *attr,
396 					 const char *buf, size_t count)
397 {
398 	struct rnbd_clt_dev *dev;
399 	char *opt, *options;
400 	int err;
401 
402 	opt = kstrdup(buf, GFP_KERNEL);
403 	if (!opt)
404 		return -ENOMEM;
405 
406 	options = strstrip(opt);
407 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
408 	if (!sysfs_streq(options, "1")) {
409 		rnbd_clt_err(dev,
410 			      "remap_device: Invalid value: %s\n",
411 			      options);
412 		err = -EINVAL;
413 		goto out;
414 	}
415 	err = rnbd_clt_remap_device(dev);
416 	if (likely(!err))
417 		err = count;
418 
419 out:
420 	kfree(opt);
421 
422 	return err;
423 }
424 
425 static struct kobj_attribute rnbd_clt_remap_device_attr =
426 	__ATTR(remap_device, 0644, rnbd_clt_remap_dev_show,
427 	       rnbd_clt_remap_dev_store);
428 
429 static ssize_t session_show(struct kobject *kobj, struct kobj_attribute *attr,
430 			    char *page)
431 {
432 	struct rnbd_clt_dev *dev;
433 
434 	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
435 
436 	return sysfs_emit(page, "%s\n", dev->sess->sessname);
437 }
438 
439 static struct kobj_attribute rnbd_clt_session_attr =
440 	__ATTR_RO(session);
441 
442 static struct attribute *rnbd_dev_attrs[] = {
443 	&rnbd_clt_unmap_device_attr.attr,
444 	&rnbd_clt_resize_dev_attr.attr,
445 	&rnbd_clt_remap_device_attr.attr,
446 	&rnbd_clt_mapping_path_attr.attr,
447 	&rnbd_clt_state_attr.attr,
448 	&rnbd_clt_session_attr.attr,
449 	&rnbd_clt_access_mode.attr,
450 	&rnbd_clt_nr_poll_queues.attr,
451 	NULL,
452 };
453 
454 void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
455 {
456 	/*
457 	 * The module unload rnbd_client_exit path is racing with unmapping of
458 	 * the last single device from the sysfs manually
459 	 * i.e. rnbd_clt_unmap_dev_store() leading to a sysfs warning because
460 	 * of sysfs link already was removed already.
461 	 */
462 	if (dev->blk_symlink_name) {
463 		if (try_module_get(THIS_MODULE)) {
464 			sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
465 			module_put(THIS_MODULE);
466 		}
467 		/* It should be freed always. */
468 		kfree(dev->blk_symlink_name);
469 		dev->blk_symlink_name = NULL;
470 	}
471 }
472 
473 static struct kobj_type rnbd_dev_ktype = {
474 	.sysfs_ops      = &kobj_sysfs_ops,
475 	.default_attrs  = rnbd_dev_attrs,
476 };
477 
478 static int rnbd_clt_add_dev_kobj(struct rnbd_clt_dev *dev)
479 {
480 	int ret;
481 	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;
482 
483 	ret = kobject_init_and_add(&dev->kobj, &rnbd_dev_ktype, gd_kobj, "%s",
484 				   "rnbd");
485 	if (ret) {
486 		rnbd_clt_err(dev, "Failed to create device sysfs dir, err: %d\n",
487 			      ret);
488 		kobject_put(&dev->kobj);
489 	}
490 	kobject_uevent(gd_kobj, KOBJ_ONLINE);
491 
492 	return ret;
493 }
494 
495 static ssize_t rnbd_clt_map_device_show(struct kobject *kobj,
496 					 struct kobj_attribute *attr,
497 					 char *page)
498 {
499 	return sysfs_emit(page,
500 			  "Usage: echo \"[dest_port=server port number] sessname=<name of the rtrs session> path=<[srcaddr@]dstaddr> [path=<[srcaddr@]dstaddr>] device_path=<full path on remote side> [access_mode=<ro|rw|migration>] [nr_poll_queues=<number of queues>]\" > %s\n\naddr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ]\n",
501 			 attr->attr.name);
502 }
503 
504 static int rnbd_clt_get_path_name(struct rnbd_clt_dev *dev, char *buf,
505 				   size_t len)
506 {
507 	int ret;
508 	char pathname[NAME_MAX], *s;
509 
510 	strscpy(pathname, dev->pathname, sizeof(pathname));
511 	while ((s = strchr(pathname, '/')))
512 		s[0] = '!';
513 
514 	ret = snprintf(buf, len, "%s@%s", pathname, dev->sess->sessname);
515 	if (ret >= len)
516 		return -ENAMETOOLONG;
517 
518 	return 0;
519 }
520 
521 static int rnbd_clt_add_dev_symlink(struct rnbd_clt_dev *dev)
522 {
523 	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;
524 	int ret, len;
525 
526 	len = strlen(dev->pathname) + strlen(dev->sess->sessname) + 2;
527 	dev->blk_symlink_name = kzalloc(len, GFP_KERNEL);
528 	if (!dev->blk_symlink_name) {
529 		rnbd_clt_err(dev, "Failed to allocate memory for blk_symlink_name\n");
530 		return -ENOMEM;
531 	}
532 
533 	ret = rnbd_clt_get_path_name(dev, dev->blk_symlink_name,
534 				      len);
535 	if (ret) {
536 		rnbd_clt_err(dev, "Failed to get /sys/block symlink path, err: %d\n",
537 			      ret);
538 		goto out_err;
539 	}
540 
541 	ret = sysfs_create_link(rnbd_devs_kobj, gd_kobj,
542 				dev->blk_symlink_name);
543 	if (ret) {
544 		rnbd_clt_err(dev, "Creating /sys/block symlink failed, err: %d\n",
545 			      ret);
546 		goto out_err;
547 	}
548 
549 	return 0;
550 
551 out_err:
552 	kfree(dev->blk_symlink_name);
553 	dev->blk_symlink_name = NULL ;
554 	return ret;
555 }
556 
557 static ssize_t rnbd_clt_map_device_store(struct kobject *kobj,
558 					  struct kobj_attribute *attr,
559 					  const char *buf, size_t count)
560 {
561 	struct rnbd_clt_dev *dev;
562 	struct rnbd_map_options opt;
563 	int ret;
564 	char pathname[NAME_MAX];
565 	char sessname[NAME_MAX];
566 	enum rnbd_access_mode access_mode = RNBD_ACCESS_RW;
567 	u16 port_nr = RTRS_PORT;
568 	u32 nr_poll_queues = 0;
569 
570 	struct sockaddr_storage *addrs;
571 	struct rtrs_addr paths[6];
572 	size_t path_cnt;
573 
574 	opt.sessname = sessname;
575 	opt.paths = paths;
576 	opt.path_cnt = &path_cnt;
577 	opt.pathname = pathname;
578 	opt.dest_port = &port_nr;
579 	opt.access_mode = &access_mode;
580 	opt.nr_poll_queues = &nr_poll_queues;
581 	addrs = kcalloc(ARRAY_SIZE(paths) * 2, sizeof(*addrs), GFP_KERNEL);
582 	if (!addrs)
583 		return -ENOMEM;
584 
585 	for (path_cnt = 0; path_cnt < ARRAY_SIZE(paths); path_cnt++) {
586 		paths[path_cnt].src = &addrs[path_cnt * 2];
587 		paths[path_cnt].dst = &addrs[path_cnt * 2 + 1];
588 	}
589 
590 	ret = rnbd_clt_parse_map_options(buf, ARRAY_SIZE(paths), &opt);
591 	if (ret)
592 		goto out;
593 
594 	pr_info("Mapping device %s on session %s, (access_mode: %s, nr_poll_queues: %d)\n",
595 		pathname, sessname,
596 		rnbd_access_mode_str(access_mode),
597 		nr_poll_queues);
598 
599 	dev = rnbd_clt_map_device(sessname, paths, path_cnt, port_nr, pathname,
600 				  access_mode, nr_poll_queues);
601 	if (IS_ERR(dev)) {
602 		ret = PTR_ERR(dev);
603 		goto out;
604 	}
605 
606 	ret = rnbd_clt_add_dev_kobj(dev);
607 	if (ret)
608 		goto unmap_dev;
609 
610 	ret = rnbd_clt_add_dev_symlink(dev);
611 	if (ret)
612 		goto unmap_dev;
613 
614 	kfree(addrs);
615 	return count;
616 
617 unmap_dev:
618 	rnbd_clt_unmap_device(dev, true, NULL);
619 out:
620 	kfree(addrs);
621 	return ret;
622 }
623 
624 static struct kobj_attribute rnbd_clt_map_device_attr =
625 	__ATTR(map_device, 0644,
626 	       rnbd_clt_map_device_show, rnbd_clt_map_device_store);
627 
628 static struct attribute *default_attrs[] = {
629 	&rnbd_clt_map_device_attr.attr,
630 	NULL,
631 };
632 
633 static struct attribute_group default_attr_group = {
634 	.attrs = default_attrs,
635 };
636 
637 static const struct attribute_group *default_attr_groups[] = {
638 	&default_attr_group,
639 	NULL,
640 };
641 
642 int rnbd_clt_create_sysfs_files(void)
643 {
644 	int err;
645 
646 	rnbd_dev_class = class_create(THIS_MODULE, "rnbd-client");
647 	if (IS_ERR(rnbd_dev_class))
648 		return PTR_ERR(rnbd_dev_class);
649 
650 	rnbd_dev = device_create_with_groups(rnbd_dev_class, NULL,
651 					      MKDEV(0, 0), NULL,
652 					      default_attr_groups, "ctl");
653 	if (IS_ERR(rnbd_dev)) {
654 		err = PTR_ERR(rnbd_dev);
655 		goto cls_destroy;
656 	}
657 	rnbd_devs_kobj = kobject_create_and_add("devices", &rnbd_dev->kobj);
658 	if (!rnbd_devs_kobj) {
659 		err = -ENOMEM;
660 		goto dev_destroy;
661 	}
662 
663 	return 0;
664 
665 dev_destroy:
666 	device_destroy(rnbd_dev_class, MKDEV(0, 0));
667 cls_destroy:
668 	class_destroy(rnbd_dev_class);
669 
670 	return err;
671 }
672 
673 void rnbd_clt_destroy_sysfs_files(void)
674 {
675 	sysfs_remove_group(&rnbd_dev->kobj, &default_attr_group);
676 	kobject_del(rnbd_devs_kobj);
677 	kobject_put(rnbd_devs_kobj);
678 	device_destroy(rnbd_dev_class, MKDEV(0, 0));
679 	class_destroy(rnbd_dev_class);
680 }
681