// SPDX-License-Identifier: GPL-2.0
/*
 * fs/sysfs/dir.c - sysfs core and dir operation implementation
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 *
 * Please see Documentation/filesystems/sysfs.rst for more information.
 */

#define pr_fmt(fmt)     "sysfs: " fmt

#include <linux/fs.h>
#include <linux/kobject.h>
#include <linux/slab.h>
#include "sysfs.h"

DEFINE_SPINLOCK(sysfs_symlink_target_lock);

void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
{
        char *buf;

        buf = kzalloc(PATH_MAX, GFP_KERNEL);
        if (buf)
                kernfs_path(parent, buf, PATH_MAX);

        pr_warn("cannot create duplicate filename '%s/%s'\n", buf, name);
        dump_stack();

        kfree(buf);
}

/**
 * sysfs_create_dir_ns - create a directory for an object with a namespace tag
 * @kobj: object we're creating directory for
 * @ns: the namespace tag to use
 */
int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
{
        struct kernfs_node *parent, *kn;
        kuid_t uid;
        kgid_t gid;

        if (WARN_ON(!kobj))
                return -EINVAL;

        if (kobj->parent)
                parent = kobj->parent->sd;
        else
                parent = sysfs_root_kn;

        if (!parent)
                return -ENOENT;

        kobject_get_ownership(kobj, &uid, &gid);

        kn = kernfs_create_dir_ns(parent, kobject_name(kobj), 0755, uid, gid,
                                  kobj, ns);
        if (IS_ERR(kn)) {
                if (PTR_ERR(kn) == -EEXIST)
                        sysfs_warn_dup(parent, kobject_name(kobj));
                return PTR_ERR(kn);
        }

        kobj->sd = kn;
        return 0;
}

/**
 *      sysfs_remove_dir - remove an object's directory.
 *      @kobj:  object.
 *
 *      The only thing special about this is that we remove any files in
 *      the directory before we remove the directory, and we've inlined
 *      what used to be sysfs_rmdir() below, instead of calling separately.
 */
void sysfs_remove_dir(struct kobject *kobj)
{
        struct kernfs_node *kn = kobj->sd;

        /*
         * In general, kobject owner is responsible for ensuring removal
         * doesn't race with other operations and sysfs doesn't provide any
         * protection; however, when @kobj is used as a symlink target, the
         * symlinking entity usually doesn't own @kobj and thus has no
         * control over removal.  @kobj->sd may be removed anytime
         * and symlink code may end up dereferencing an already freed node.
         *
         * sysfs_symlink_target_lock synchronizes @kobj->sd
         * disassociation against symlink operations so that symlink code
         * can safely dereference @kobj->sd.
         */
        spin_lock(&sysfs_symlink_target_lock);
        kobj->sd = NULL;
        spin_unlock(&sysfs_symlink_target_lock);

        if (kn) {
                WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
                kernfs_remove(kn);
        }
}

int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
                        const void *new_ns)
{
        struct kernfs_node *parent;
        int ret;

        parent = kernfs_get_parent(kobj->sd);
        ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
        kernfs_put(parent);
        return ret;
}

int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
                      const void *new_ns)
{
        struct kernfs_node *kn = kobj->sd;
        struct kernfs_node *new_parent;

        new_parent = new_parent_kobj && new_parent_kobj->sd ?
                new_parent_kobj->sd : sysfs_root_kn;

        return kernfs_rename_ns(kn, new_parent, NULL, new_ns);
}

/**
 * sysfs_create_mount_point - create an always empty directory
 * @parent_kobj:  kobject that will contain this always empty directory
 * @name: The name of the always empty directory to add
 */
int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
{
        struct kernfs_node *kn, *parent = parent_kobj->sd;

        kn = kernfs_create_empty_dir(parent, name);
        if (IS_ERR(kn)) {
                if (PTR_ERR(kn) == -EEXIST)
                        sysfs_warn_dup(parent, name);
                return PTR_ERR(kn);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(sysfs_create_mount_point);

/**
 *      sysfs_remove_mount_point - remove an always empty directory.
 *      @parent_kobj: kobject that will contain this always empty directory
 *      @name: The name of the always empty directory to remove
 *
 */
void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
{
        struct kernfs_node *parent = parent_kobj->sd;

        kernfs_remove_by_name_ns(parent, name, NULL);
}
EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);