bpf_get_file_xattr
BTF_ID_FLAGS(func, bpf_get_file_xattr, KF_SLEEPABLE)
extern int bpf_get_file_xattr(struct file *file, const char *name,
ret = bpf_get_file_xattr(f, xattr_names[i], &value_ptr);
ret = bpf_get_file_xattr(f, "user.sig", &sig_ptr);