[PATCH 17/24] ibnbd: client: sysfs interface functions

[Roman Pen <roman.penyaev@profitbricks.com>]

This is the sysfs interface to IBNBD block devices on client side:

  /sys/kernel/ibnbd_client/
    |- map_device
    |  *** maps remote device
    |
    |- devices/
       *** all mapped devices

  /sys/block/ibnbd<N>/ibnbd_client/
    |- unmap_device
    |  *** unmaps device
    |
    |- state
    |  *** device state
    |
    |- session
    |  *** session name
    |
    |- mapping_path
       *** path of the dev that was mapped on server

Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Signed-off-by: Danil Kipnis <danil.kipnis@profitbricks.com>
Cc: Jack Wang <jinpu.wang@profitbricks.com>
---
 drivers/block/ibnbd/ibnbd-clt-sysfs.c | 723 ++++++++++++++++++++++++++++++++++
 1 file changed, 723 insertions(+)

diff --git a/drivers/block/ibnbd/ibnbd-clt-sysfs.c b/drivers/block/ibnbd/ibnbd-clt-sysfs.c
new file mode 100644
index 000000000000..2770b5c81c23
--- /dev/null
+++ b/drivers/block/ibnbd/ibnbd-clt-sysfs.c
@@ -0,0 +1,723 @@
+/*
+ * InfiniBand Network Block Driver
+ *
+ * Copyright (c) 2014 - 2017 ProfitBricks GmbH. All rights reserved.
+ * Authors: Fabian Holler <mail@fholler.de>
+ *          Jack Wang <jinpu.wang@profitbricks.com>
+ *          Kleber Souza <kleber.souza@profitbricks.com>
+ *          Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *          Milind Dumbare <Milind.dumbare@gmail.com>
+ *
+ * Copyright (c) 2017 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Authors: Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
+
+#include <linux/types.h>
+#include <linux/ctype.h>
+#include <linux/parser.h>
+#include <linux/module.h>
+#include <linux/in6.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <rdma/ib.h>
+#include <rdma/rdma_cm.h>
+
+#include "ibnbd-clt.h"
+
+static struct kobject *ibnbd_kobject;
+static struct kobject *ibnbd_devices_kobject;
+
+enum {
+	IBNBD_OPT_ERR		= 0,
+	IBNBD_OPT_PATH		= 1 << 0,
+	IBNBD_OPT_DEV_PATH	= 1 << 1,
+	IBNBD_OPT_ACCESS_MODE	= 1 << 3,
+	IBNBD_OPT_INPUT_MODE	= 1 << 4,
+	IBNBD_OPT_IO_MODE	= 1 << 5,
+	IBNBD_OPT_SESSNAME	= 1 << 6,
+};
+
+static unsigned int ibnbd_opt_mandatory[] = {
+	IBNBD_OPT_PATH,
+	IBNBD_OPT_DEV_PATH,
+	IBNBD_OPT_SESSNAME,
+};
+
+static const match_table_t ibnbd_opt_tokens = {
+	{	IBNBD_OPT_PATH,		"path=%s"		},
+	{	IBNBD_OPT_DEV_PATH,	"device_path=%s"	},
+	{	IBNBD_OPT_ACCESS_MODE,	"access_mode=%s"	},
+	{	IBNBD_OPT_INPUT_MODE,	"input_mode=%s"		},
+	{	IBNBD_OPT_IO_MODE,	"io_mode=%s"		},
+	{	IBNBD_OPT_SESSNAME,	"sessname=%s"		},
+	{	IBNBD_OPT_ERR,		NULL			},
+};
+
+/* remove new line from string */
+static void strip(char *s)
+{
+	char *p = s;
+
+	while (*s != '\0') {
+		if (*s != '\n')
+			*p++ = *s++;
+		else
+			++s;
+	}
+	*p = '\0';
+}
+
+static int ibnbd_clt_parse_map_options(const char *buf,
+				       char *sessname,
+				       struct ibtrs_addr *paths,
+				       size_t *path_cnt,
+				       size_t max_path_cnt,
+				       char *pathname,
+				       enum ibnbd_access_mode *access_mode,
+				       enum ibnbd_queue_mode *queue_mode,
+				       enum ibnbd_io_mode *io_mode)
+{
+	char *options, *sep_opt;
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int opt_mask = 0;
+	int token;
+	int ret = -EINVAL;
+	int i;
+	int p_cnt = 0;
+
+	options = kstrdup(buf, GFP_KERNEL);
+	if (!options)
+		return -ENOMEM;
+
+	options = strstrip(options);
+	strip(options);
+	sep_opt = options;
+	while ((p = strsep(&sep_opt, " ")) != NULL) {
+		if (!*p)
+			continue;
+
+		token = match_token(p, ibnbd_opt_tokens, args);
+		opt_mask |= token;
+
+		switch (token) {
+		case IBNBD_OPT_SESSNAME:
+			p = match_strdup(args);
+			if (!p) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			if (strlen(p) > NAME_MAX) {
+				pr_err("map_device: sessname too long\n");
+				ret = -EINVAL;
+				kfree(p);
+				goto out;
+			}
+			strlcpy(sessname, p, NAME_MAX);
+			kfree(p);
+			break;
+
+		case IBNBD_OPT_PATH:
+			p = match_strdup(args);
+			if (!p || p_cnt >= max_path_cnt) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			ret = ibtrs_addr_to_sockaddr(p, strlen(p), IBTRS_PORT,
+						     &paths[p_cnt]);
+			if (ret) {
+				pr_err("Can't parse path %s: %d\n", p, ret);
+				kfree(p);
+				goto out;
+			}
+
+			p_cnt++;
+
+			kfree(p);
+			break;
+
+		case IBNBD_OPT_DEV_PATH:
+			p = match_strdup(args);
+			if (!p) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			if (strlen(p) > NAME_MAX) {
+				pr_err("map_device: Device path too long\n");
+				ret = -EINVAL;
+				kfree(p);
+				goto out;
+			}
+			strlcpy(pathname, p, NAME_MAX);
+			kfree(p);
+			break;
+
+		case IBNBD_OPT_ACCESS_MODE:
+			p = match_strdup(args);
+			if (!p) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			if (!strcmp(p, "ro")) {
+				*access_mode = IBNBD_ACCESS_RO;
+			} else if (!strcmp(p, "rw")) {
+				*access_mode = IBNBD_ACCESS_RW;
+			} else if (!strcmp(p, "migration")) {
+				*access_mode = IBNBD_ACCESS_MIGRATION;
+			} else {
+				pr_err("map_device: Invalid access_mode:"
+				       " '%s'\n", p);
+				ret = -EINVAL;
+				kfree(p);
+				goto out;
+			}
+
+			kfree(p);
+			break;
+
+		case IBNBD_OPT_INPUT_MODE:
+			p = match_strdup(args);
+			if (!p) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			if (!strcmp(p, "mq")) {
+				*queue_mode = BLK_MQ;
+			} else if (!strcmp(p, "rq")) {
+				*queue_mode = BLK_RQ;
+			} else {
+				pr_err("map_device: Invalid input_mode: "
+				       "'%s'.\n", p);
+				ret = -EINVAL;
+				kfree(p);
+				goto out;
+			}
+			kfree(p);
+			break;
+
+		case IBNBD_OPT_IO_MODE:
+			p = match_strdup(args);
+			if (!p) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			if (!strcmp(p, "blockio")) {
+				*io_mode = IBNBD_BLOCKIO;
+			} else if (!strcmp(p, "fileio")) {
+				*io_mode = IBNBD_FILEIO;
+			} else {
+				pr_err("map_device: Invalid io_mode: '%s'.\n",
+				       p);
+				ret = -EINVAL;
+				kfree(p);
+				goto out;
+			}
+			kfree(p);
+			break;
+
+		default:
+			pr_err("map_device: Unknown parameter or missing value"
+			       " '%s'\n", p);
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	for (i = 0; i < ARRAY_SIZE(ibnbd_opt_mandatory); i++) {
+		if ((opt_mask & ibnbd_opt_mandatory[i])) {
+			ret = 0;
+		} else {
+			pr_err("map_device: Parameters missing\n");
+			ret = -EINVAL;
+			break;
+		}
+	}
+
+out:
+	*path_cnt = p_cnt;
+	kfree(options);
+	return ret;
+}
+
+static ssize_t ibnbd_clt_state_show(struct kobject *kobj,
+				    struct kobj_attribute *attr, char *page)
+{
+	struct ibnbd_clt_dev *dev;
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+
+	switch (dev->dev_state) {
+	case (DEV_STATE_INIT):
+		return scnprintf(page, PAGE_SIZE, "init\n");
+	case (DEV_STATE_MAPPED):
+		/* TODO fix cli tool before changing to proper state */
+		return scnprintf(page, PAGE_SIZE, "open\n");
+	case (DEV_STATE_MAPPED_DISCONNECTED):
+		/* TODO fix cli tool before changing to proper state */
+		return scnprintf(page, PAGE_SIZE, "closed\n");
+	case (DEV_STATE_UNMAPPED):
+		return scnprintf(page, PAGE_SIZE, "unmapped\n");
+	default:
+		return scnprintf(page, PAGE_SIZE, "unknown\n");
+	}
+}
+
+static struct kobj_attribute ibnbd_clt_state_attr =
+	__ATTR(state, 0444, ibnbd_clt_state_show, NULL);
+
+static ssize_t ibnbd_clt_input_mode_show(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 char *page)
+{
+	struct ibnbd_clt_dev *dev;
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+
+	return scnprintf(page, PAGE_SIZE, "%s\n",
+			 ibnbd_queue_mode_str(dev->queue_mode));
+}
+
+static struct kobj_attribute ibnbd_clt_input_mode_attr =
+	__ATTR(input_mode, 0444, ibnbd_clt_input_mode_show, NULL);
+
+static ssize_t ibnbd_clt_mapping_path_show(struct kobject *kobj,
+					   struct kobj_attribute *attr,
+					   char *page)
+{
+	struct ibnbd_clt_dev *dev;
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+
+	return scnprintf(page, PAGE_SIZE, "%s\n", dev->pathname);
+}
+
+static struct kobj_attribute ibnbd_clt_mapping_path_attr =
+	__ATTR(mapping_path, 0444, ibnbd_clt_mapping_path_show, NULL);
+
+static ssize_t ibnbd_clt_io_mode_show(struct kobject *kobj,
+				      struct kobj_attribute *attr, char *page)
+{
+	struct ibnbd_clt_dev *dev;
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+
+	return scnprintf(page, PAGE_SIZE, "%s\n",
+			 ibnbd_io_mode_str(dev->remote_io_mode));
+}
+
+static struct kobj_attribute ibnbd_clt_io_mode =
+	__ATTR(io_mode, 0444, ibnbd_clt_io_mode_show, NULL);
+
+static ssize_t ibnbd_clt_unmap_dev_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *page)
+{
+	return scnprintf(page, PAGE_SIZE, "Usage: echo <normal|force> > %s\n",
+			 attr->attr.name);
+}
+
+void ibnbd_sysfs_remove_file_self(struct kobject *kobj,
+				  const struct attribute *attr)
+{
+	struct device_attribute dattr = {
+		.attr.name = attr->name
+	};
+	struct device *device;
+
+	/*
+	 * Unfortunately original sysfs_remove_file_self() is not exported,
+	 * so consider this as a hack to call self removal of a sysfs entry
+	 * just using another "door".
+	 */
+
+	device = container_of(kobj, typeof(*device), kobj);
+	device_remove_file_self(device, &dattr);
+}
+
+static ssize_t ibnbd_clt_unmap_dev_store(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct ibnbd_clt_dev *dev;
+	char *options;
+	bool force;
+	int err;
+
+	options = kstrdup(buf, GFP_KERNEL);
+	if (!options)
+		return -ENOMEM;
+
+	options = strstrip(options);
+	strip(options);
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+
+	if (sysfs_streq(options, "normal")) {
+		force = false;
+	} else if (sysfs_streq(options, "force")) {
+		force = true;
+	} else {
+		ibnbd_err(dev, "unmap_device: Invalid value: %s\n", options);
+		err = -EINVAL;
+		goto out;
+	}
+
+	ibnbd_info(dev, "Unmapping device, option: %s.\n",
+		   force ? "force" : "normal");
+
+	/*
+	 * We take explicit module reference only for one reason: do not
+	 * race with lockless ibnbd_destroy_sessions().
+	 */
+	if (!try_module_get(THIS_MODULE)) {
+		err = -ENODEV;
+		goto out;
+	}
+	err = ibnbd_clt_unmap_device(dev, force, &attr->attr);
+	if (unlikely(err)) {
+		if (unlikely(err != -EALREADY))
+			ibnbd_err(dev, "unmap_device: %d\n",  err);
+		goto module_put;
+	}
+
+	/*
+	 * Here device can be vanished!
+	 */
+
+	err = count;
+
+module_put:
+	module_put(THIS_MODULE);
+out:
+	kfree(options);
+
+	return err;
+}
+
+static struct kobj_attribute ibnbd_clt_unmap_device_attr =
+	__ATTR(unmap_device, 0644, ibnbd_clt_unmap_dev_show,
+	       ibnbd_clt_unmap_dev_store);
+
+static ssize_t ibnbd_clt_resize_dev_show(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 char *page)
+{
+	return scnprintf(page, PAGE_SIZE,
+			 "Usage: echo <new size in sectors> > %s\n",
+			 attr->attr.name);
+}
+
+static ssize_t ibnbd_clt_resize_dev_store(struct kobject *kobj,
+					  struct kobj_attribute *attr,
+					  const char *buf, size_t count)
+{
+	int ret;
+	unsigned long sectors;
+	struct ibnbd_clt_dev *dev;
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+
+	ret = kstrtoul(buf, 0, &sectors);
+	if (ret)
+		return ret;
+
+	ret = ibnbd_clt_resize_disk(dev, (size_t)sectors);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static struct kobj_attribute ibnbd_clt_resize_dev_attr =
+	__ATTR(resize, 0644, ibnbd_clt_resize_dev_show,
+	       ibnbd_clt_resize_dev_store);
+
+static ssize_t ibnbd_clt_remap_dev_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *page)
+{
+	return scnprintf(page, PAGE_SIZE, "Usage: echo <1> > %s\n",
+			 attr->attr.name);
+}
+
+static ssize_t ibnbd_clt_remap_dev_store(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct ibnbd_clt_dev *dev;
+	char *options;
+	int err;
+
+	options = kstrdup(buf, GFP_KERNEL);
+	if (!options)
+		return -ENOMEM;
+
+	options = strstrip(options);
+	strip(options);
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+	if (!sysfs_streq(options, "1")) {
+		ibnbd_err(dev, "remap_device: Invalid value: %s\n", options);
+		err = -EINVAL;
+		goto out;
+	}
+	err = ibnbd_clt_remap_device(dev);
+	if (likely(!err))
+		err = count;
+
+out:
+	kfree(options);
+
+	return err;
+}
+
+static struct kobj_attribute ibnbd_clt_remap_device_attr =
+	__ATTR(remap_device, 0644, ibnbd_clt_remap_dev_show,
+	       ibnbd_clt_remap_dev_store);
+
+static ssize_t ibnbd_clt_session_show(struct kobject *kobj,
+				      struct kobj_attribute *attr,
+				      char *page)
+{
+	struct ibnbd_clt_dev *dev;
+
+	dev = container_of(kobj, struct ibnbd_clt_dev, kobj);
+
+	return scnprintf(page, PAGE_SIZE, "%s\n", dev->sess->sessname);
+}
+
+static struct kobj_attribute ibnbd_clt_session_attr =
+	__ATTR(session, 0444, ibnbd_clt_session_show, NULL);
+
+static struct attribute *ibnbd_dev_attrs[] = {
+	&ibnbd_clt_unmap_device_attr.attr,
+	&ibnbd_clt_resize_dev_attr.attr,
+	&ibnbd_clt_remap_device_attr.attr,
+	&ibnbd_clt_mapping_path_attr.attr,
+	&ibnbd_clt_state_attr.attr,
+	&ibnbd_clt_input_mode_attr.attr,
+	&ibnbd_clt_session_attr.attr,
+	&ibnbd_clt_io_mode.attr,
+	NULL,
+};
+
+void ibnbd_clt_remove_dev_symlink(struct ibnbd_clt_dev *dev)
+{
+	/*
+	 * The module_is_live() check is crucial and helps to avoid annoying
+	 * sysfs warning raised in sysfs_remove_link(), when the whole sysfs
+	 * path was just removed, see ibnbd_close_sessions().
+	 */
+	if (strlen(dev->blk_symlink_name) && module_is_live(THIS_MODULE))
+		sysfs_remove_link(ibnbd_devices_kobject, dev->blk_symlink_name);
+}
+
+static struct kobj_type ibnbd_dev_ktype = {
+	.sysfs_ops      = &kobj_sysfs_ops,
+	.default_attrs  = ibnbd_dev_attrs,
+};
+
+static int ibnbd_clt_add_dev_kobj(struct ibnbd_clt_dev *dev)
+{
+	int ret;
+	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;
+
+	ret = kobject_init_and_add(&dev->kobj, &ibnbd_dev_ktype, gd_kobj, "%s",
+				   "ibnbd");
+	if (ret)
+		ibnbd_err(dev, "Failed to create device sysfs dir, err: %d\n",
+			  ret);
+
+	return ret;
+}
+
+static ssize_t ibnbd_clt_map_device_show(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 char *page)
+{
+	return scnprintf(page, PAGE_SIZE, "Usage: echo \""
+			 "sessname=<name of the ibtrs session>"
+			 " path=<[srcaddr,]dstaddr>"
+			 " [path=<[srcaddr,]dstaddr>]"
+			 " device_path=<full path on remote side>"
+			 " [access_mode=<ro|rw|migration>]"
+			 " [input_mode=<mq|rq>]"
+			 " [io_mode=<fileio|blockio>]\" > %s\n\n"
+			 "addr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ]\n",
+			 attr->attr.name);
+}
+
+static int ibnbd_clt_get_path_name(struct ibnbd_clt_dev *dev, char *buf,
+				   size_t len)
+{
+	int ret;
+	char pathname[NAME_MAX], *s;
+
+	strlcpy(pathname, dev->pathname, sizeof(pathname));
+	while ((s = strchr(pathname, '/')))
+		s[0] = '!';
+
+	ret = snprintf(buf, len, "%s", pathname);
+	if (ret >= len)
+		return -ENAMETOOLONG;
+
+	return 0;
+}
+
+static int ibnbd_clt_add_dev_symlink(struct ibnbd_clt_dev *dev)
+{
+	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;
+	int ret;
+
+	ret = ibnbd_clt_get_path_name(dev, dev->blk_symlink_name,
+				      sizeof(dev->blk_symlink_name));
+	if (ret) {
+		ibnbd_err(dev, "Failed to get /sys/block symlink path, err: %d\n",
+			  ret);
+		goto out_err;
+	}
+
+	ret = sysfs_create_link(ibnbd_devices_kobject, gd_kobj,
+				dev->blk_symlink_name);
+	if (ret) {
+		ibnbd_err(dev, "Creating /sys/block symlink failed, err: %d\n",
+			  ret);
+		goto out_err;
+	}
+
+	return 0;
+
+out_err:
+	dev->blk_symlink_name[0] = '\0';
+	return ret;
+}
+
+static ssize_t ibnbd_clt_map_device_store(struct kobject *kobj,
+					  struct kobj_attribute *attr,
+					  const char *buf, size_t count)
+{
+	struct ibnbd_clt_dev *dev;
+	int ret;
+	char pathname[NAME_MAX];
+	char sessname[NAME_MAX];
+	enum ibnbd_access_mode access_mode = IBNBD_ACCESS_RW;
+	enum ibnbd_queue_mode queue_mode = BLK_MQ;
+	enum ibnbd_io_mode io_mode = IBNBD_AUTOIO;
+
+	size_t path_cnt;
+	struct ibtrs_addr paths[3];
+	struct sockaddr_storage saddr[ARRAY_SIZE(paths)];
+	struct sockaddr_storage daddr[ARRAY_SIZE(paths)];
+
+	for (path_cnt = 0; path_cnt < ARRAY_SIZE(paths); path_cnt++) {
+		paths[path_cnt].src = (struct sockaddr *)&saddr[path_cnt];
+		paths[path_cnt].dst = (struct sockaddr *)&daddr[path_cnt];
+	}
+
+	ret = ibnbd_clt_parse_map_options(buf, sessname, paths,
+					  &path_cnt, ARRAY_SIZE(paths),
+					  pathname, &access_mode,
+					  &queue_mode, &io_mode);
+	if (ret)
+		return ret;
+
+	pr_info("Mapping device %s on session %s,"
+		" (access_mode: %s, input_mode: %s, io_mode: %s)\n",
+		pathname, sessname, ibnbd_access_mode_str(access_mode),
+		ibnbd_queue_mode_str(queue_mode), ibnbd_io_mode_str(io_mode));
+
+	dev = ibnbd_clt_map_device(sessname, paths, path_cnt, pathname,
+				   access_mode, queue_mode, io_mode);
+	if (unlikely(IS_ERR(dev)))
+		return PTR_ERR(dev);
+
+	ret = ibnbd_clt_add_dev_kobj(dev);
+	if (unlikely(ret))
+		goto unmap_dev;
+
+	ret = ibnbd_clt_add_dev_symlink(dev);
+	if (ret)
+		goto unmap_dev;
+
+	return count;
+
+unmap_dev:
+	ibnbd_clt_unmap_device(dev, true, NULL);
+
+	return ret;
+}
+
+static struct kobj_attribute ibnbd_clt_map_device_attr =
+	__ATTR(map_device, 0644,
+	       ibnbd_clt_map_device_show, ibnbd_clt_map_device_store);
+
+static struct attribute *default_attrs[] = {
+	&ibnbd_clt_map_device_attr.attr,
+	NULL,
+};
+
+static struct attribute_group default_attr_group = {
+	.attrs = default_attrs,
+};
+
+int ibnbd_clt_create_sysfs_files(void)
+{
+	int err = 0;
+
+	ibnbd_kobject = kobject_create_and_add(KBUILD_MODNAME, kernel_kobj);
+	if (!ibnbd_kobject) {
+		err = -ENOMEM;
+		goto err1;
+	}
+
+	ibnbd_devices_kobject = kobject_create_and_add("devices",
+						       ibnbd_kobject);
+	if (!ibnbd_devices_kobject) {
+		err = -ENOMEM;
+		goto err2;
+	}
+
+	err = sysfs_create_group(ibnbd_kobject, &default_attr_group);
+	if (err)
+		goto err3;
+
+	return 0;
+
+err3:
+	kobject_put(ibnbd_devices_kobject);
+err2:
+	kobject_put(ibnbd_kobject);
+err1:
+	return err;
+}
+
+void ibnbd_clt_destroy_default_group(void)
+{
+	sysfs_remove_group(ibnbd_kobject, &default_attr_group);
+}
+
+void ibnbd_clt_destroy_sysfs_files(void)
+{
+	kobject_del(ibnbd_devices_kobject);
+	kobject_put(ibnbd_devices_kobject);
+	kobject_del(ibnbd_kobject);
+	kobject_put(ibnbd_kobject);
+}
-- 
2.13.1