Hi Eric,
On Tue, Jun 2, 2009 at 12:50 AM, Eric W. Biederman
<ebiederm@xxxxxxxxxxxx> wrote:
> +#ifdef CONFIG_FILE_HOTPLUG
> +
> +static bool file_in_use(struct file *file)
> +{
> + struct task_struct *leader, *task;
> + bool in_use = false;
> + int i;
> +
> + rcu_read_lock();
> + do_each_thread(leader, task) {
> + for (i = 0; i < MAX_FILE_HOTPLUG_LOCK_DEPTH; i++) {
> + if (task->file_hotplug_lock[i] == file) {
> + in_use = true;
> + goto found;
> + }
> + }
> + } while_each_thread(leader, task);
> +found:
> + rcu_read_unlock();
> + return in_use;
> +}
This seems rather heavy-weight. If we're going to use this
infrastructure for forced unmount, I think this will be a problem.
Can't we two this in two stages: (1) mark a bit that forces
file_hotplug_read_trylock to always fail and (2) block until the last
remaining in-kernel file_hotplug_read_unlock() has executed?
Pekka
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