// 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/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 <linux/device.h>
#include <rdma/ib.h>
#include <rdma/rdma_cm.h>

#include "rnbd-clt.h"

static struct device *rnbd_dev;
static const struct class rnbd_dev_class = {
	.name = "rnbd-client",
};
static struct kobject *rnbd_devs_kobj;

enum {
	RNBD_OPT_ERR		= 0,
	RNBD_OPT_DEST_PORT	= 1 << 0,
	RNBD_OPT_PATH		= 1 << 1,
	RNBD_OPT_DEV_PATH	= 1 << 2,
	RNBD_OPT_ACCESS_MODE	= 1 << 3,
	RNBD_OPT_SESSNAME	= 1 << 6,
	RNBD_OPT_NR_POLL_QUEUES	= 1 << 7,
};

static const unsigned int rnbd_opt_mandatory[] = {
	RNBD_OPT_DEV_PATH,
	RNBD_OPT_SESSNAME,
};

static const match_table_t rnbd_opt_tokens = {
	{RNBD_OPT_PATH,			"path=%s"		},
	{RNBD_OPT_DEV_PATH,		"device_path=%s"	},
	{RNBD_OPT_DEST_PORT,		"dest_port=%d"		},
	{RNBD_OPT_ACCESS_MODE,		"access_mode=%s"	},
	{RNBD_OPT_SESSNAME,		"sessname=%s"		},
	{RNBD_OPT_NR_POLL_QUEUES,	"nr_poll_queues=%d"	},
	{RNBD_OPT_ERR,			NULL			},
};

struct rnbd_map_options {
	char *sessname;
	struct rtrs_addr *paths;
	size_t *path_cnt;
	char *pathname;
	u16 *dest_port;
	enum rnbd_access_mode *access_mode;
	u32 *nr_poll_queues;
};

static int rnbd_clt_parse_map_options(const char *buf, size_t max_path_cnt,
				       struct rnbd_map_options *opt)
{
	char *options, *sep_opt;
	char *p;
	substring_t args[MAX_OPT_ARGS];
	int opt_mask = 0;
	int token;
	int ret = -EINVAL;
	int nr_poll_queues = 0;
	int dest_port = 0;
	int p_cnt = 0;
	int i;

	options = kstrdup(buf, GFP_KERNEL);
	if (!options)
		return -ENOMEM;

	sep_opt = strstrip(options);
	while ((p = strsep(&sep_opt, " ")) != NULL) {
		if (!*p)
			continue;

		token = match_token(p, rnbd_opt_tokens, args);
		opt_mask |= token;

		switch (token) {
		case RNBD_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;
			}
			strscpy(opt->sessname, p, NAME_MAX);
			kfree(p);
			break;

		case RNBD_OPT_PATH:
			if (p_cnt >= max_path_cnt) {
				pr_err("map_device: too many (> %zu) paths provided\n",
				       max_path_cnt);
				ret = -ENOMEM;
				goto out;
			}
			p = match_strdup(args);
			if (!p) {
				ret = -ENOMEM;
				goto out;
			}

			ret = rtrs_addr_to_sockaddr(p, strlen(p),
						    *opt->dest_port,
						    &opt->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 RNBD_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;
			}
			strscpy(opt->pathname, p, NAME_MAX);
			kfree(p);
			break;

		case RNBD_OPT_DEST_PORT:
			if (match_int(args, &dest_port) || dest_port < 0 ||
			    dest_port > 65535) {
				pr_err("bad destination port number parameter '%d'\n",
				       dest_port);
				ret = -EINVAL;
				goto out;
			}
			*opt->dest_port = dest_port;
			break;

		case RNBD_OPT_ACCESS_MODE:
			p = match_strdup(args);
			if (!p) {
				ret = -ENOMEM;
				goto out;
			}

			if (!strcmp(p, "ro")) {
				*opt->access_mode = RNBD_ACCESS_RO;
			} else if (!strcmp(p, "rw")) {
				*opt->access_mode = RNBD_ACCESS_RW;
			} else if (!strcmp(p, "migration")) {
				*opt->access_mode = RNBD_ACCESS_MIGRATION;
			} else {
				pr_err("map_device: Invalid access_mode: '%s'\n",
				       p);
				ret = -EINVAL;
				kfree(p);
				goto out;
			}

			kfree(p);
			break;

		case RNBD_OPT_NR_POLL_QUEUES:
			if (match_int(args, &nr_poll_queues) || nr_poll_queues < -1 ||
			    nr_poll_queues > (int)nr_cpu_ids) {
				pr_err("bad nr_poll_queues parameter '%d'\n",
				       nr_poll_queues);
				ret = -EINVAL;
				goto out;
			}
			if (nr_poll_queues == -1)
				nr_poll_queues = nr_cpu_ids;
			*opt->nr_poll_queues = nr_poll_queues;
			break;

		default:
			pr_err("map_device: Unknown parameter or missing value '%s'\n",
			       p);
			ret = -EINVAL;
			goto out;
		}
	}

	for (i = 0; i < ARRAY_SIZE(rnbd_opt_mandatory); i++) {
		if ((opt_mask & rnbd_opt_mandatory[i])) {
			ret = 0;
		} else {
			pr_err("map_device: Parameters missing\n");
			ret = -EINVAL;
			break;
		}
	}

out:
	*opt->path_cnt = p_cnt;
	kfree(options);
	return ret;
}

static ssize_t state_show(struct kobject *kobj,
			  struct kobj_attribute *attr, char *page)
{
	struct rnbd_clt_dev *dev;

	dev = container_of(kobj, struct rnbd_clt_dev, kobj);

	switch (dev->dev_state) {
	case DEV_STATE_INIT:
		return sysfs_emit(page, "init\n");
	case DEV_STATE_MAPPED:
		/* TODO fix cli tool before changing to proper state */
		return sysfs_emit(page, "open\n");
	case DEV_STATE_MAPPED_DISCONNECTED:
		/* TODO fix cli tool before changing to proper state */
		return sysfs_emit(page, "closed\n");
	case DEV_STATE_UNMAPPED:
		return sysfs_emit(page, "unmapped\n");
	default:
		return sysfs_emit(page, "unknown\n");
	}
}

static struct kobj_attribute rnbd_clt_state_attr = __ATTR_RO(state);

static ssize_t nr_poll_queues_show(struct kobject *kobj,
				   struct kobj_attribute *attr, char *page)
{
	struct rnbd_clt_dev *dev;

	dev = container_of(kobj, struct rnbd_clt_dev, kobj);

	return sysfs_emit(page, "%d\n", dev->nr_poll_queues);
}

static struct kobj_attribute rnbd_clt_nr_poll_queues =
	__ATTR_RO(nr_poll_queues);

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

	dev = container_of(kobj, struct rnbd_clt_dev, kobj);

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

static struct kobj_attribute rnbd_clt_mapping_path_attr =
	__ATTR_RO(mapping_path);

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

	dev = container_of(kobj, struct rnbd_clt_dev, kobj);

	return sysfs_emit(page, "%s\n", rnbd_access_modes[dev->access_mode].str);
}

static struct kobj_attribute rnbd_clt_access_mode =
	__ATTR_RO(access_mode);

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

static ssize_t rnbd_clt_unmap_dev_store(struct kobject *kobj,
					 struct kobj_attribute *attr,
					 const char *buf, size_t count)
{
	struct rnbd_clt_dev *dev;
	char *opt, *options;
	bool force;
	int err;

	opt = kstrdup(buf, GFP_KERNEL);
	if (!opt)
		return -ENOMEM;

	options = strstrip(opt);
	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
	if (sysfs_streq(options, "normal")) {
		force = false;
	} else if (sysfs_streq(options, "force")) {
		force = true;
	} else {
		rnbd_clt_err(dev,
			      "unmap_device: Invalid value: %s\n",
			      options);
		err = -EINVAL;
		goto out;
	}

	rnbd_clt_info(dev, "Unmapping device, option: %s.\n",
		       force ? "force" : "normal");

	/*
	 * We take explicit module reference only for one reason: do not
	 * race with lockless rnbd_destroy_sessions().
	 */
	if (!try_module_get(THIS_MODULE)) {
		err = -ENODEV;
		goto out;
	}
	err = rnbd_clt_unmap_device(dev, force, &attr->attr);
	if (err) {
		if (err != -EALREADY)
			rnbd_clt_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(opt);

	return err;
}

static struct kobj_attribute rnbd_clt_unmap_device_attr =
	__ATTR(unmap_device, 0644, rnbd_clt_unmap_dev_show,
	       rnbd_clt_unmap_dev_store);

static ssize_t rnbd_clt_resize_dev_show(struct kobject *kobj,
					 struct kobj_attribute *attr,
					 char *page)
{
	return sysfs_emit(page, "Usage: echo <new size in sectors> > %s\n",
			  attr->attr.name);
}

static ssize_t rnbd_clt_resize_dev_store(struct kobject *kobj,
					  struct kobj_attribute *attr,
					  const char *buf, size_t count)
{
	int ret;
	unsigned long sectors;
	struct rnbd_clt_dev *dev;

	dev = container_of(kobj, struct rnbd_clt_dev, kobj);

	ret = kstrtoul(buf, 0, &sectors);
	if (ret)
		return ret;

	ret = rnbd_clt_resize_disk(dev, sectors);
	if (ret)
		return ret;

	return count;
}

static struct kobj_attribute rnbd_clt_resize_dev_attr =
	__ATTR(resize, 0644, rnbd_clt_resize_dev_show,
	       rnbd_clt_resize_dev_store);

static ssize_t rnbd_clt_remap_dev_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_clt_remap_dev_store(struct kobject *kobj,
					 struct kobj_attribute *attr,
					 const char *buf, size_t count)
{
	struct rnbd_clt_dev *dev;
	char *opt, *options;
	int err;

	opt = kstrdup(buf, GFP_KERNEL);
	if (!opt)
		return -ENOMEM;

	options = strstrip(opt);
	dev = container_of(kobj, struct rnbd_clt_dev, kobj);
	if (!sysfs_streq(options, "1")) {
		rnbd_clt_err(dev,
			      "remap_device: Invalid value: %s\n",
			      options);
		err = -EINVAL;
		goto out;
	}
	err = rnbd_clt_remap_device(dev);
	if (likely(!err))
		err = count;

out:
	kfree(opt);

	return err;
}

static struct kobj_attribute rnbd_clt_remap_device_attr =
	__ATTR(remap_device, 0644, rnbd_clt_remap_dev_show,
	       rnbd_clt_remap_dev_store);

static ssize_t session_show(struct kobject *kobj, struct kobj_attribute *attr,
			    char *page)
{
	struct rnbd_clt_dev *dev;

	dev = container_of(kobj, struct rnbd_clt_dev, kobj);

	return sysfs_emit(page, "%s\n", dev->sess->sessname);
}

static struct kobj_attribute rnbd_clt_session_attr =
	__ATTR_RO(session);

static struct attribute *rnbd_dev_attrs[] = {
	&rnbd_clt_unmap_device_attr.attr,
	&rnbd_clt_resize_dev_attr.attr,
	&rnbd_clt_remap_device_attr.attr,
	&rnbd_clt_mapping_path_attr.attr,
	&rnbd_clt_state_attr.attr,
	&rnbd_clt_session_attr.attr,
	&rnbd_clt_access_mode.attr,
	&rnbd_clt_nr_poll_queues.attr,
	NULL,
};
ATTRIBUTE_GROUPS(rnbd_dev);

void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
{
	/*
	 * The module unload rnbd_client_exit path is racing with unmapping of
	 * the last single device from the sysfs manually
	 * i.e. rnbd_clt_unmap_dev_store() leading to a sysfs warning because
	 * of sysfs link already was removed already.
	 */
	if (dev->blk_symlink_name) {
		if (try_module_get(THIS_MODULE)) {
			sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
			module_put(THIS_MODULE);
		}
		/* It should be freed always. */
		kfree(dev->blk_symlink_name);
		dev->blk_symlink_name = NULL;
	}
}

static const struct kobj_type rnbd_dev_ktype = {
	.sysfs_ops      = &kobj_sysfs_ops,
	.default_groups = rnbd_dev_groups,
};

static int rnbd_clt_add_dev_kobj(struct rnbd_clt_dev *dev)
{
	int ret;
	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;

	ret = kobject_init_and_add(&dev->kobj, &rnbd_dev_ktype, gd_kobj, "%s",
				   "rnbd");
	if (ret) {
		rnbd_clt_err(dev, "Failed to create device sysfs dir, err: %d\n",
			      ret);
		kobject_put(&dev->kobj);
	}
	kobject_uevent(gd_kobj, KOBJ_ONLINE);

	return ret;
}

static ssize_t rnbd_clt_map_device_show(struct kobject *kobj,
					 struct kobj_attribute *attr,
					 char *page)
{
	return sysfs_emit(page,
			  "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",
			 attr->attr.name);
}

static int rnbd_clt_get_path_name(struct rnbd_clt_dev *dev, char *buf,
				   size_t len)
{
	int ret;
	char pathname[NAME_MAX], *s;

	strscpy(pathname, dev->pathname, sizeof(pathname));
	while ((s = strchr(pathname, '/')))
		s[0] = '!';

	ret = snprintf(buf, len, "%s@%s", pathname, dev->sess->sessname);
	if (ret >= len)
		return -ENAMETOOLONG;

	return 0;
}

static int rnbd_clt_add_dev_symlink(struct rnbd_clt_dev *dev)
{
	struct kobject *gd_kobj = &disk_to_dev(dev->gd)->kobj;
	int ret, len;

	len = strlen(dev->pathname) + strlen(dev->sess->sessname) + 2;
	dev->blk_symlink_name = kzalloc(len, GFP_KERNEL);
	if (!dev->blk_symlink_name) {
		rnbd_clt_err(dev, "Failed to allocate memory for blk_symlink_name\n");
		return -ENOMEM;
	}

	ret = rnbd_clt_get_path_name(dev, dev->blk_symlink_name,
				      len);
	if (ret) {
		rnbd_clt_err(dev, "Failed to get /sys/block symlink path, err: %d\n",
			      ret);
		goto out_err;
	}

	ret = sysfs_create_link(rnbd_devs_kobj, gd_kobj,
				dev->blk_symlink_name);
	if (ret) {
		rnbd_clt_err(dev, "Creating /sys/block symlink failed, err: %d\n",
			      ret);
		goto out_err;
	}

	return 0;

out_err:
	kfree(dev->blk_symlink_name);
	dev->blk_symlink_name = NULL ;
	return ret;
}

static ssize_t rnbd_clt_map_device_store(struct kobject *kobj,
					  struct kobj_attribute *attr,
					  const char *buf, size_t count)
{
	struct rnbd_clt_dev *dev;
	struct rnbd_map_options opt;
	int ret;
	char pathname[NAME_MAX];
	char sessname[NAME_MAX];
	enum rnbd_access_mode access_mode = RNBD_ACCESS_RW;
	u16 port_nr = RTRS_PORT;
	u32 nr_poll_queues = 0;

	struct sockaddr_storage *addrs;
	struct rtrs_addr paths[6];
	size_t path_cnt;

	opt.sessname = sessname;
	opt.paths = paths;
	opt.path_cnt = &path_cnt;
	opt.pathname = pathname;
	opt.dest_port = &port_nr;
	opt.access_mode = &access_mode;
	opt.nr_poll_queues = &nr_poll_queues;
	addrs = kcalloc(ARRAY_SIZE(paths) * 2, sizeof(*addrs), GFP_KERNEL);
	if (!addrs)
		return -ENOMEM;

	for (path_cnt = 0; path_cnt < ARRAY_SIZE(paths); path_cnt++) {
		paths[path_cnt].src = &addrs[path_cnt * 2];
		paths[path_cnt].dst = &addrs[path_cnt * 2 + 1];
	}

	ret = rnbd_clt_parse_map_options(buf, ARRAY_SIZE(paths), &opt);
	if (ret)
		goto out;

	pr_info("Mapping device %s on session %s, (access_mode: %s, nr_poll_queues: %d)\n",
		pathname, sessname,
		rnbd_access_modes[access_mode].str,
		nr_poll_queues);

	dev = rnbd_clt_map_device(sessname, paths, path_cnt, port_nr, pathname,
				  access_mode, nr_poll_queues);
	if (IS_ERR(dev)) {
		ret = PTR_ERR(dev);
		goto out;
	}

	ret = rnbd_clt_add_dev_kobj(dev);
	if (ret)
		goto unmap_dev;

	ret = rnbd_clt_add_dev_symlink(dev);
	if (ret)
		goto unmap_dev;

	kfree(addrs);
	return count;

unmap_dev:
	rnbd_clt_unmap_device(dev, true, NULL);
out:
	kfree(addrs);
	return ret;
}

static struct kobj_attribute rnbd_clt_map_device_attr =
	__ATTR(map_device, 0644,
	       rnbd_clt_map_device_show, rnbd_clt_map_device_store);

static struct attribute *default_attrs[] = {
	&rnbd_clt_map_device_attr.attr,
	NULL,
};

static struct attribute_group default_attr_group = {
	.attrs = default_attrs,
};

static const struct attribute_group *default_attr_groups[] = {
	&default_attr_group,
	NULL,
};

int rnbd_clt_create_sysfs_files(void)
{
	int err;

	err = class_register(&rnbd_dev_class);
	if (err)
		return err;

	rnbd_dev = device_create_with_groups(&rnbd_dev_class, NULL,
					      MKDEV(0, 0), NULL,
					      default_attr_groups, "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_unregister(&rnbd_dev_class);

	return err;
}

void rnbd_clt_destroy_sysfs_files(void)
{
	sysfs_remove_group(&rnbd_dev->kobj, &default_attr_group);
	kobject_del(rnbd_devs_kobj);
	kobject_put(rnbd_devs_kobj);
	device_destroy(&rnbd_dev_class, MKDEV(0, 0));
	class_unregister(&rnbd_dev_class);
}