// 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 <uapi/linux/limits.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/stat.h>
#include <linux/genhd.h>
#include <linux/list.h>
#include <linux/moduleparam.h>
#include <linux/device.h>

#include "rnbd-srv.h"

static struct device *rnbd_dev;
static struct class *rnbd_dev_class;
static struct kobject *rnbd_devs_kobj;

static void rnbd_srv_dev_release(struct kobject *kobj)
{
        struct rnbd_srv_dev *dev;

        dev = container_of(kobj, struct rnbd_srv_dev, dev_kobj);

        kfree(dev);
}

static struct kobj_type dev_ktype = {
        .sysfs_ops = &kobj_sysfs_ops,
        .release = rnbd_srv_dev_release
};

int rnbd_srv_create_dev_sysfs(struct rnbd_srv_dev *dev,
                               struct block_device *bdev,
                               const char *dev_name)
{
        struct kobject *bdev_kobj;
        int ret;

        ret = kobject_init_and_add(&dev->dev_kobj, &dev_ktype,
                                   rnbd_devs_kobj, dev_name);
        if (ret) {
                kobject_put(&dev->dev_kobj);
                return ret;
        }

        dev->dev_sessions_kobj = kobject_create_and_add("sessions",
                                                        &dev->dev_kobj);
        if (!dev->dev_sessions_kobj) {
                ret = -ENOMEM;
                goto free_dev_kobj;
        }

        bdev_kobj = &disk_to_dev(bdev->bd_disk)->kobj;
        ret = sysfs_create_link(&dev->dev_kobj, bdev_kobj, "block_dev");
        if (ret)
                goto put_sess_kobj;

        return 0;

put_sess_kobj:
        kobject_put(dev->dev_sessions_kobj);
free_dev_kobj:
        kobject_del(&dev->dev_kobj);
        kobject_put(&dev->dev_kobj);
        return ret;
}

void rnbd_srv_destroy_dev_sysfs(struct rnbd_srv_dev *dev)
{
        sysfs_remove_link(&dev->dev_kobj, "block_dev");
        kobject_del(dev->dev_sessions_kobj);
        kobject_put(dev->dev_sessions_kobj);
        kobject_del(&dev->dev_kobj);
        kobject_put(&dev->dev_kobj);
}

static ssize_t read_only_show(struct kobject *kobj, struct kobj_attribute *attr,
                              char *page)
{
        struct rnbd_srv_sess_dev *sess_dev;

        sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);

        return sysfs_emit(page, "%d\n",
                          !(sess_dev->open_flags & FMODE_WRITE));
}

static struct kobj_attribute rnbd_srv_dev_session_ro_attr =
        __ATTR_RO(read_only);

static ssize_t access_mode_show(struct kobject *kobj,
                                struct kobj_attribute *attr,
                                char *page)
{
        struct rnbd_srv_sess_dev *sess_dev;

        sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);

        return sysfs_emit(page, "%s\n",
                          rnbd_access_mode_str(sess_dev->access_mode));
}

static struct kobj_attribute rnbd_srv_dev_session_access_mode_attr =
        __ATTR_RO(access_mode);

static ssize_t mapping_path_show(struct kobject *kobj,
                                 struct kobj_attribute *attr, char *page)
{
        struct rnbd_srv_sess_dev *sess_dev;

        sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);

        return sysfs_emit(page, "%s\n", sess_dev->pathname);
}

static struct kobj_attribute rnbd_srv_dev_session_mapping_path_attr =
        __ATTR_RO(mapping_path);

static ssize_t rnbd_srv_dev_session_force_close_show(struct kobject *kobj,
                                        struct kobj_attribute *attr, char *page)
{
        return sysfs_emit(page, "Usage: echo 1 > %s\n",
                          attr->attr.name);
}

static ssize_t rnbd_srv_dev_session_force_close_store(struct kobject *kobj,
                                        struct kobj_attribute *attr,
                                        const char *buf, size_t count)
{
        struct rnbd_srv_sess_dev *sess_dev;

        sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);

        if (!sysfs_streq(buf, "1")) {
                rnbd_srv_err(sess_dev, "%s: invalid value: '%s'\n",
                              attr->attr.name, buf);
                return -EINVAL;
        }

        rnbd_srv_info(sess_dev, "force close requested\n");
        rnbd_srv_sess_dev_force_close(sess_dev, attr);

        return count;
}

static struct kobj_attribute rnbd_srv_dev_session_force_close_attr =
        __ATTR(force_close, 0644,
               rnbd_srv_dev_session_force_close_show,
               rnbd_srv_dev_session_force_close_store);

static struct attribute *rnbd_srv_default_dev_sessions_attrs[] = {
        &rnbd_srv_dev_session_access_mode_attr.attr,
        &rnbd_srv_dev_session_ro_attr.attr,
        &rnbd_srv_dev_session_mapping_path_attr.attr,
        &rnbd_srv_dev_session_force_close_attr.attr,
        NULL,
};

static struct attribute_group rnbd_srv_default_dev_session_attr_group = {
        .attrs = rnbd_srv_default_dev_sessions_attrs,
};

void rnbd_srv_destroy_dev_session_sysfs(struct rnbd_srv_sess_dev *sess_dev)
{
        sysfs_remove_group(&sess_dev->kobj,
                           &rnbd_srv_default_dev_session_attr_group);

        kobject_del(&sess_dev->kobj);
        kobject_put(&sess_dev->kobj);
}

static void rnbd_srv_sess_dev_release(struct kobject *kobj)
{
        struct rnbd_srv_sess_dev *sess_dev;

        sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
        rnbd_destroy_sess_dev(sess_dev, sess_dev->keep_id);
}

static struct kobj_type rnbd_srv_sess_dev_ktype = {
        .sysfs_ops      = &kobj_sysfs_ops,
        .release        = rnbd_srv_sess_dev_release,
};

int rnbd_srv_create_dev_session_sysfs(struct rnbd_srv_sess_dev *sess_dev)
{
        int ret;

        ret = kobject_init_and_add(&sess_dev->kobj, &rnbd_srv_sess_dev_ktype,
                                   sess_dev->dev->dev_sessions_kobj, "%s",
                                   sess_dev->sess->sessname);
        if (ret) {
                kobject_put(&sess_dev->kobj);
                return ret;
        }

        ret = sysfs_create_group(&sess_dev->kobj,
                                 &rnbd_srv_default_dev_session_attr_group);
        if (ret) {
                kobject_del(&sess_dev->kobj);
                kobject_put(&sess_dev->kobj);
        }

        return ret;
}

int rnbd_srv_create_sysfs_files(void)
{
        int err;

        rnbd_dev_class = class_create(THIS_MODULE, "rnbd-server");
        if (IS_ERR(rnbd_dev_class))
                return PTR_ERR(rnbd_dev_class);

        rnbd_dev = device_create(rnbd_dev_class, NULL,
                                  MKDEV(0, 0), NULL, "ctl");
        if (IS_ERR(rnbd_dev)) {
                err = PTR_ERR(rnbd_dev);
                goto cls_destroy;
        }
        rnbd_devs_kobj = kobject_create_and_add("devices", &rnbd_dev->kobj);
        if (!rnbd_devs_kobj) {
                err = -ENOMEM;
                goto dev_destroy;
        }

        return 0;

dev_destroy:
        device_destroy(rnbd_dev_class, MKDEV(0, 0));
cls_destroy:
        class_destroy(rnbd_dev_class);

        return err;
}

void rnbd_srv_destroy_sysfs_files(void)
{
        kobject_del(rnbd_devs_kobj);
        kobject_put(rnbd_devs_kobj);
        device_destroy(rnbd_dev_class, MKDEV(0, 0));
        class_destroy(rnbd_dev_class);
}