waiting for device to exist

[N3xp7im3]

It might be possible that the storage device does not probe fast enough causing an error when trying to mount it. Thus, we should wait for it passively before proceeding with the code. Depending on which features are enabled we have to wait at different code paths.

[michaelolbrich]

The clippy error is also present in main. It changed with the latest rust version. That will need a separate fix.

[michaelolbrich]

Please rebase. That should fix the failed tests.

[michaelolbrich]

cargo fmt complains about that. But maybe there is a better way to do this?
@hnez do you have any suggestions?

[hnez]

(I've posted my reply as a separate comment - I must have clicked the wrong buttons)

[hnez]

Suggested change

	if options.rootfstype != Some("nfs".to_string()) &&
	options.rootfstype != Some("9p".to_string())
	{
	let root_device = options.root.as_ref().ok_or("No root device argument")?;
	wait_for_device(root_device)?;
	}
	match options.rootfstype.as_deref() {
	Some("nfs") | Some("9p") => (),
	_ => wait_for_device(root)?,
	}

This relies on a change I made above which I can not format as suggestion here. My local mount_root looks like this:

pub fn mount_root(options: &CmdlineOptions) -> Result<()> {
    let root = options
        .root
        .as_ref()
        .ok_or("root= not found in /proc/cmdline")?;

    match options.rootfstype.as_deref() {
        Some("nfs") | Some("9p") => (),
        _ => wait_for_device(root)?,
    }

    mkdir("/root")?;

    debug!(
        "Mounting rootfs {} -> /root as {} with flags = {:#x}, data = '{}'",
        root,
        options.rootfstype.as_deref().unwrap_or_default(),
        options.rootfsflags.bits(),
        options.rootflags.as_deref().unwrap_or_default()
    );
    do_mount(
        Some(root),
        "/root",
        options.rootfstype.as_deref(),
        options.rootfsflags,
        options.rootflags.as_deref(),
    )?;

    Ok(())
}

[hnez]

The main.rs already contains a few helper functions like this one, so adding this one there is consistent.
But I think they should be moved somewhere else in the future (utils.rs?) to de-clutter the main.rs (it is the entrypoint for newcomers to a project and should thus, in my opinion, be the easiest file to read).

[michaelolbrich]

Good point. We have #6 do move stuff into a separate file. But that PR tried to do too much stuff at once and has not been merged so far.

[hnez]

Suggested change

	fn wait_for_device(root_device: &str) -> Result<()> {
	let mut counter = 0;
	while !Path::new(&root_device).exists() {
	let duration = time::Duration::from_millis(5);
	if counter > 1000 {
	return Err("timout reached while waiting for the device".into());
	}
	thread::sleep(duration);
	counter += 1;
	}
	Ok(())
	}
	fn wait_for_device(root_device: &str) -> Result<()> {
	let duration = time::Duration::from_millis(5);
	let path = Path::new(&root_device);
	for _ in 0..1000 {
	if path.exists() {
	return Ok(());
	}
	thread::sleep(duration);
	}
	Err("timout reached while waiting for the device".into())
	}