[CRIU] [RFC PATCH 3/5] cr-restore: restore root sid before mount namespace

[Pavel Emelyanov]

On 11/23/2015 08:22 PM, Stanislav Kinsburskiy wrote:
> This is a precursor patch for AutoFS mount restore.
> To restore AutoFS-nested mount points, we have to created target dentries.
> To be able to do so, the process have to be process group leader before AutoFS
> mount is called.

Where does this requirement come from?

> Note: there is another way, how to set process as a group leader. We can fork
> a child with CLONE_VM, and use it to mount all the mount points.
> 
> Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
> ---
>  cr-restore.c |    8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/cr-restore.c b/cr-restore.c
> index 06fceb6..9aec077 100644
> --- a/cr-restore.c
> +++ b/cr-restore.c
> @@ -1441,7 +1441,10 @@ static int create_children_and_session(void)
>  			return ret;
>  	}
>  
> -	restore_sid();
> +	if (getpid() == 1)
> +		pr_info("Skipping restore_sid() for init\n");
> +	else
> +		restore_sid();
>  
>  	pr_info("Restoring children in our session:\n");
>  	list_for_each_entry(child, &current->children, sibling) {
> @@ -1524,6 +1527,9 @@ static int restore_task_with_children(void *_arg)
>  		if (restore_finish_stage(CR_STATE_RESTORE_NS) < 0)
>  			goto err;
>  
> +		pr_info("Calling restore_sid() for init\n");
> +		restore_sid();

In the patch comment you say that process has to be group leader, but
make it session leader instead. Why?

> +
>  		/*
>  		 * We need non /proc proc mount for restoring pid and mount
>  		 * namespaces and do not care for the rest of the cases.
> 
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