Path lookup in linux kernel 4.15

I'm trying to write a simple kernel module, just for didactic purpose. In particular, what is giving me headaches is the path lookup. I'd like to have a sysfs entry and in the store operation I want to receive a buffer and I want to save it only if it's a valid path. So I tried to use the vfs_path_lookup Exported Symbols from here namei.c. But even inserting a valid path, it prints me the ENOENT error.

This is my code:

Into the header:

extern int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *, unsigned int, struct path *path);

Into the module store function:

ssize_t path_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count){

            int err = vfs_path_lookup(current->fs->root.dentry, current->fs->root.mnt, buf, LOOKUP_DIRECTORY, base_path);
            printk(KERN_DEBUG "%s\n", __FUNCTION__);
            printk(KERN_DEBUG "Received: %s err is %d\n", buf, err);        

            strncpy(base_addr, buf, MAX_FILENAME_SIZE);
            printk(KERN_DEBUG "Base Addr: %s\n", base_addr);
            return strlen(base_addr);
        }

What I tried to write into the file is the string "/home/osboxes/Documents" that is an existing directory. I suspect that I didn't get the real usage of the function, maybe something with flags. Thank you in advance for your help.

Edit: This is the example requested into the comments (Thanks again)

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/kobject.h> 
#include <linux/sysfs.h>



#define MAX_FILENAME_SIZE 256

struct path *base_path ;
struct kobject *conf_kobj;
char base_addr[MAX_FILENAME_SIZE] = "/home/osboxes/Documenti";

struct kobj_attribute *get_attribute(char *name, umode_t mode, ssize_t (*show)(struct kobject *, struct kobj_attribute *, char *), ssize_t (*store)(struct kobject *, struct kobj_attribute *,
             const char *, size_t));

ssize_t path_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf){
                printk(KERN_DEBUG "%s\n", __FUNCTION__);

                return sprintf(buf, "%s", base_addr);
            }
ssize_t path_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count){

                int err = kern_path(buf, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, base_path);
                printk(KERN_DEBUG "%s\n", __FUNCTION__);
                printk(KERN_DEBUG "Received: %s err is %d\n", buf, err);        

                strncpy(base_addr, buf, MAX_FILENAME_SIZE);
                printk(KERN_DEBUG "Base Addr: %s\n", base_addr);
                return strlen(base_addr);
            }



static int __init init_mymodule(void)
{   
    struct kobj_attribute *path_attr;

    printk(KERN_DEBUG "Module inserted\n");

    path_attr = get_attribute(base_addr, 0666, path_show, path_store);
    base_path = kmalloc(sizeof(struct path), GFP_KERNEL);

    conf_kobj = kobject_create_and_add("conf", kernel_kobj);


    sysfs_create_file(conf_kobj, &path_attr->attr);

    return 0;

}



struct kobj_attribute *get_attribute(char *name, umode_t mode, ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr, char *buf), ssize_t (*store)(struct kobject *kobj, struct kobj_attribute *attr,
             const char *buf, size_t count))
{
    struct kobj_attribute *attribute = kmalloc(sizeof(struct kobj_attribute), GFP_KERNEL);

    attribute->attr.name = name;
    attribute->attr.mode = mode;
    if(show)
        attribute->show = show;
    if(store)
        attribute->store = store;
    return attribute;

}

static void __exit exit_mymodule(void)
{

    kobject_put(conf_kobj);
    kfree(base_addr);
    printk(KERN_INFO "Module removed\n");
}



module_init(init_mymodule);
module_exit(exit_mymodule);

MODULE_LICENSE("GPL");

I also replaced vfs_path_lookup with kern_path as @Tsyvarev suggested. The error comes when I write into the terminal

echo "/home/osboxes/Documenti"> /sys/kernel/conf/path

When I use the address into the "buf" variable, in this case it's hardcoded, but doesn't work.