linux kernel I/O

I am trying to modify the rm_dir command on the linux kernel. I want to add a confirmation request. something like: "Are you sure you want to erase this directory (Y/N): "

I have found the implementation (or at least I think I have) under fs directory for file-systems. I think there must be some sort of a manager that checks what file system is used on the particular architecture, which then calls the appropriate implementation of the deleting process. However, I could not find such a "manager" function. All I found was the following macro:

SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
{
    return do_rmdir(AT_FDCWD, pathname);
}

this simply calls the function do_rmdir just above it. here it is:

static long do_rmdir(int dfd, const char __user *pathname)
{
    int error = 0;
    struct filename *name;
    struct dentry *dentry;
    struct nameidata nd;
    unsigned int lookup_flags = 0;
retry:
    name = user_path_parent(dfd, pathname, &nd, lookup_flags);
    if (IS_ERR(name))
        return PTR_ERR(name);

    switch(nd.last_type) {
    case LAST_DOTDOT:
        error = -ENOTEMPTY;
        goto exit1;
    case LAST_DOT:
        error = -EINVAL;
        goto exit1;
    case LAST_ROOT:
        error = -EBUSY;
        goto exit1;
    }

    nd.flags &= ~LOOKUP_PARENT;
    error = mnt_want_write(nd.path.mnt);
    if (error)
        goto exit1;

    mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
    dentry = lookup_hash(&nd);
    error = PTR_ERR(dentry);
    if (IS_ERR(dentry))
        goto exit2;
    if (!dentry->d_inode) {
        error = -ENOENT;
        goto exit3;
    }
    error = security_path_rmdir(&nd.path, dentry);
    if (error)
        goto exit3;
    error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
exit3:
    dput(dentry);
exit2:
    mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
    mnt_drop_write(nd.path.mnt);
exit1:
    path_put(&nd.path);
    putname(name);
    if (retry_estale(error, lookup_flags)) {
        lookup_flags |= LOOKUP_REVAL;
        goto retry;
    }
    return error;
}

I tried adding a printk statement, but the result is outside of the actual UML that uses that kernel. The result simply doesn't show in the correct UML window - (the one that uses this kernel). I am not sure how to do I/O in kernel space. Can somebody help? Thanks.