[CRIU] [PATCH 01/10] namespaces: add switch_ns_by_fd

[Pavel Emelyanov]

On 02/13/2017 08:49 AM, Andrei Vagin wrote:
> From: Andrei Vagin <avagin at virtuozzo.com>
> 
> It's like switch_ns, but it gets a namespace file descriptor instead of pid.

I've already wrote this comment, but ...

It looks like the switch_ns_by_fd is already in the code, so this
patch does something different rather than adding this routine :)

What should I write as subject/body when merging this patch?

-- Pavel

> Signed-off-by: Andrei Vagin <avagin at virtuozzo.com>
> ---
>  criu/mount.c | 15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
> 
> diff --git a/criu/mount.c b/criu/mount.c
> index cbbc154..42f2eb8 100644
> --- a/criu/mount.c
> +++ b/criu/mount.c
> @@ -2835,15 +2835,7 @@ int depopulate_roots_yard(int mntns_fd, bool only_ghosts)
>  		return -1;
>  	}
>  
> -	old_ns = open_proc(PROC_SELF, "ns/mnt");
> -	if (old_ns < 0) {
> -		pr_perror("`- Can't keep old ns");
> -		close(old_cwd);
> -		return -1;
> -	}
> -	if (setns(mntns_fd, CLONE_NEWNS) < 0) {
> -		pr_perror("`- Can't switch");
> -		close(old_ns);
> +	if (switch_ns_by_fd(mntns_fd, &mnt_ns_desc, &old_ns)) {
>  		close(old_cwd);
>  		return -1;
>  	}
> @@ -2854,11 +2846,8 @@ int depopulate_roots_yard(int mntns_fd, bool only_ghosts)
>  	if (__depopulate_roots_yard())
>  		ret = -1;
>  
> -	if (setns(old_ns, CLONE_NEWNS) < 0) {
> -		pr_perror("Fail to switch back!");
> +	if (restore_ns(old_ns, &mnt_ns_desc))
>  		ret = -1;
> -	}
> -	close(old_ns);
>  
>  	if (fchdir(old_cwd)) {
>  		pr_perror("Unable to restore cwd");
>