[PATCH v2 1/3] fs: Introduce task path helpers

[Jann Horn]

On Mon, Aug 31, 2026 at 4:59 AM Chen Linxuan via B4 Relay
<devnull+me.black-desk.cn at kernel.org> wrote:
> Introduce helpers that acquire a referenced struct path for a task's
> executable, root, and working directory. Reuse them for procfs task
> links and AppArmor executable-path handling instead of duplicating file
> and path reference handling at each call site.
[...]
> +/**
> + * get_task_exe_path - acquire a reference to the task's executable path
> + * @task: The task.
> + * @exe_path: The task's executable path.
> + *
> + * Returns 0 if the task has an executable path, or -ENOENT if it does not.
> + * The caller must release the path through path_put() on success.
> + */
> +int get_task_exe_path(struct task_struct *task, struct path *exe_path)
> +{
> +       struct file *exe_file = get_task_exe_file(task);
> +
> +       if (!exe_file)
> +               return -ENOENT;
> +
> +       *exe_path = exe_file->f_path;
> +       path_get(exe_path);
> +       fput(exe_file);
> +       return 0;
> +}
[...]
>  static const char *get_current_exe_path(char *buffer, int buffer_size)
>  {
> -       struct file *exe_file;
> -       struct path p;
> +       struct path p __free(path_put) = {};
>         const char *path_str;
>
> -       exe_file = get_task_exe_file(current);
> -       if (!exe_file)
> +       if (get_task_exe_path(current, &p))
>                 return ERR_PTR(-ENOENT);

This assumes that when get_task_exe_path() fails, it doesn't set
members of the path argument to non-NULL values. That should be noted
in a comment above get_task_exe_path().