[CRIU] [PATCH v5 5/5] mount: Restore binfmt_misc content in case of missing mount

[Pavel Emelyanov]

On 08/04/2016 04:49 PM, Kirill Tkhai wrote:
> In case of mount image is not containing binfmt_misc mountpoint,
> add temporary mountpoint to mount tree and try to restore
> binfmt_misc content in ordinary way. Then, umount temporary mountpoint.
> 
> v4: New
> v5: Check for opts.has_binfmt_misc to determine if image presents
> 
> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
>  criu/mount.c |   19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/criu/mount.c b/criu/mount.c
> index 926817a..964dbbc 100644
> --- a/criu/mount.c
> +++ b/criu/mount.c
> @@ -2451,6 +2451,15 @@ static int do_new_mount(struct mount_info *mi)
>  	if (tp->restore && tp->restore(mi))
>  		return -1;
>  
> +	if (!mi->mnt_id) {
> +		/* C-r time mountpoint, umount it */
> +		if (umount(mi->mountpoint) < 0) {
> +			pr_perror("Can't umount %s\n", mi->mountpoint);
> +			return -1;
> +		}
> +		goto out;
> +	}
> +
>  	if (remount_ro && mount(NULL, mi->mountpoint, tp->name,
>  				     MS_REMOUNT | MS_RDONLY, NULL)) {
>  		pr_perror("Unable to apply mount options");
> @@ -2470,7 +2479,7 @@ static int do_new_mount(struct mount_info *mi)
>  	BUG_ON(mi->master_id);
>  	if (restore_shared_options(mi, !mi->shared_id, mi->shared_id, 0))
>  		return -1;
> -
> +out:
>  	mi->mounted = true;
>  
>  	return 0;
> @@ -3339,6 +3348,7 @@ static int populate_mnt_ns(void)
>  	struct mount_info *pms;
>  	struct ns_id *nsid;
>  	struct mount_info *roots_mp = NULL;
> +	struct stat st;
>  	int ret;
>  
>  	if (mnt_roots) {
> @@ -3355,6 +3365,13 @@ static int populate_mnt_ns(void)
>  	if (!pms)
>  		return -1;
>  
> +	if (!opts.has_binfmt_misc && stat_image(CR_FD_BINFMT_MISC, &st, 0) == 0) {

This should be the other way. In cr-restore.c we have an array of so called cinfos -- these
are images that should be pre-loaded during restore. So it's better to add new-style binfmt
cinfo and read_mnt_ns_img should check cinfo->flags for COLLECT_HAPPENED (not 100% sure it
handles empty images correctly, plz, check) and add cr-time mount if it had.

-- Pavel

> +		/* Add to mount tree. Generic code will mount it later */
> +		ret = add_cr_time_mount(pms, "binfmt_misc", BINFMT_MISC_HOME, 0);
> +		if (ret)
> +			return -1;
> +	}
> +
>  	if (resolve_shared_mounts(mntinfo, pms->master_id))
>  		return -1;
>  
> 
> _______________________________________________
> CRIU mailing list
> CRIU at openvz.org
> https://lists.openvz.org/mailman/listinfo/criu
> .
>