[CRIU] [PATCH v3 01/11] mount: save fs root fd of ps tree root mnt ns in its ns_id

[Pavel Emelyanov]

Cc Andrey.

This correlates with your patches that rework opening procedure.

On 08/10/2016 10:12 PM, Eugene Batalov wrote:
> New criu gc command needs to access files in every ps tree ns.
> It will use ns_id.mnt.root_fd for this.
> ps tree processes shouldn't be created during criu gc so we can't
> use /proc/$ns_pid/root based schema used in criu restore command.
> 
> Signed-off-by: Eugene Batalov <eabatalov89 at gmail.com>
> ---
>  criu/mount.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/criu/mount.c b/criu/mount.c
> index 0f81681..7bbd30b 100644
> --- a/criu/mount.c
> +++ b/criu/mount.c
> @@ -3160,8 +3160,7 @@ void fini_restore_mntns(void)
>  		if (nsid->nd != &mnt_ns_desc)
>  			continue;
>  		close_safe(&nsid->mnt.ns_fd);
> -		if (nsid->type != NS_ROOT)
> -			close_safe(&nsid->mnt.root_fd);
> +		close_safe(&nsid->mnt.root_fd);
>  		nsid->ns_populated = true;
>  	}
>  }
> @@ -3495,6 +3494,10 @@ ns_created:
>  			nsid->mnt.ns_fd = open_proc(PROC_SELF, "ns/mnt");
>  			if (nsid->mnt.ns_fd < 0)
>  				goto err;
> +			/* root_fd is used to restore file mappings */
> +			nsid->mnt.root_fd = open_proc(PROC_SELF, "root");
> +			if (nsid->mnt.root_fd < 0)
> +				goto err;
>  			/* we set ns_populated so we don't need to open root_fd */
>  			nsid->ns_populated = true;
>  			continue;
>