How to read files in linux kernel after 5.10+ [duplicate]

My linux kernel is "5.11.0-36-generic".

I want to read parameter from a file named "myTest.txt".

after make, terminal says:

error: implicit declaration of function ‘get_fs’; did you mean ‘sget_fc’? [-Werror=implicit-function-declaration] 

I have searched for answers, and found that article: Saying goodbye to set_fs()..

Can anyone tell me how to replace it?

#include <linux/module.h> #include <linux/init.h> #include <linux/fs.h> #include <linux/uaccess.h> #include <linux/string.h> #include <linux/slab.h> int __init hello_init(void) { unsigned char buf1[12]="hello world."; unsigned char buf2[12]="kernel file."; struct file *fp; mm_segment_t fs; loff_t pos; printk("hello enter\n"); fp = filp_open("/home/kernel_file", O_RDWR | O_CREAT, 0644); if (IS_ERR(fp)) { printk("create file error\n"); return -1; } fs = get_fs(); //------------------------wrong !! set_fs(KERNEL_DS);//------------------------wrong !! pos = fp->f_pos; vfs_write(fp, buf1, sizeof(buf1), &pos); fp->f_pos = pos; pos = fp->f_pos; vfs_write(fp, buf2, sizeof(buf2), &pos); fp->f_pos = pos; set_fs(fs); //------------------------wrong !! filp_close(fp, NULL); return 0; } void __exit hello_exit(void) { printk(" exit\n"); } module_init(hello_init); module_exit(hello_exit); MODULE_LICENSE("GPL");