[CRIU] [PATCH 1/5] mnt: add --ext-mount-map auto option

[Pavel Emelyanov]

> @@ -2360,7 +2510,8 @@ static int collect_mntns(struct ns_id *ns, void *__arg)
>  	if (arg->for_dump && ns->pid != getpid())
>  		arg->need_to_validate = true;
>  
> -	mntinfo_add_list(pms);
> +	if (!opts.autodetect_ext_mounts || ns->pid != getpid() || arg->really_collect_self_mounts)
> +		mntinfo_add_list(pms);

I asked about this place on the v1 of the patch :)

This if and the if for really_collect_self_mounts seems strange to me.

There are two "types" of pms we can get here -- criu's one and non-criu's
one. The former one should only be put into the global list if it's the only
one at all, i.e. -- we're having the non-ns case.

So the single if (ns->pid != getpid() || !(root_ns_mask & CLONE_NEWNS)) here
should give us what we want.

And, if I'm correct, the if in the next hunk can just go away.

-- Pavel

>  	return 0;
>  }
>  
> @@ -2371,15 +2522,34 @@ int collect_mnt_namespaces(bool for_dump)
>  
>  	arg.for_dump = for_dump;
>  	arg.need_to_validate = false;
> +	arg.really_collect_self_mounts = false;
> +
> +	/*
> +	 * XXX: this is a little bit of spaghetti. If we are autodetecting
> +	 * external mounts, we want to collect the criu pid's mountinfo (and
> +	 * thus the whole mountns) so we can corrolate the external masters.
> +	 * So we clear the mountns bit for this call to walk_namespaces.
> +	 *
> +	 * However, we don't want to add criu's mountns to the dump target
> +	 * list if it isn't really going to be dumped, so we set the
> +	 * really_collect_self_mounts flag if we really do want to collect
> +	 * them above.
> +	 */
> +	if (opts.autodetect_ext_mounts && !(root_ns_mask & CLONE_NEWNS)) {
> +		arg.really_collect_self_mounts = true;
> +	}
>  
> -	ret = walk_namespaces(&mnt_ns_desc, false, collect_mntns, &need_to_validate);
> +	ret = walk_namespaces(&mnt_ns_desc, opts.autodetect_ext_mounts, collect_mntns, &arg);
>  	if (ret)
>  		goto err;
>  
> +	if (resolve_external_mounts(mntinfo))
> +		goto err;
> +
>  	if (arg.need_to_validate) {
>  		ret = -1;
>  
> -		if (collect_shared(mntinfo))
> +		if (collect_shared(mntinfo, true))
>  			goto err;
>  		if (validate_mounts(mntinfo, true))
>  			goto err;
>