[CRIU] [PATCH] sk-unix: set mntinfo

[Christian Brauner]

On Tue, Sep 13, 2016 at 10:51:04PM +0200, Christian Brauner wrote:
> On Tue, Sep 13, 2016 at 05:53:59PM +0300, Pavel Emelyanov wrote:
> > On 09/07/2016 05:29 PM, Christian Brauner wrote:
> > > phys_stat_resolve() call mount_resolve_path() which requires that mntinfo_tree
> > > in the ns_id struct is initialized. This is a problem we observed with sockets
> > > on btrfs volumes:
> > 
> > Sorry for the late response. See my comment inline.
> > 
> > > Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
> > > ---
> > >  criu/sk-unix.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/criu/sk-unix.c b/criu/sk-unix.c
> > > index 99f0b08..a199ca4 100644
> > > --- a/criu/sk-unix.c
> > > +++ b/criu/sk-unix.c
> > > @@ -525,6 +525,7 @@ static int unix_process_name(struct unix_sk_desc *d, const struct unix_diag_msg
> > >  			ret = -ENOENT;
> > >  			goto out;
> > >  		}
> > > +		ns->mnt.mntinfo_tree = mntinfo;
> > 
> > I guess that's too late for this assignment. Since this is dump time, then
> > ns->mnt.mntinfo_tree should have been initialized in collect_mntns() or
> > nearby.
> 
> It is in collect_mntinfo() but it seems calling lookup_ns_by_id() in
> unix_process_name() does return an ns_id but ns.mnt->mntinfo_tree is not
> initialized. Is mntinfo a global that is identical for all ns_ids in the linked
> list? If not how should they be initialized?

Scratch that, collect_mntinfo() is per namespace. The question is when to call
it. One option is that as soon as you add a new ns_id you call collect_mntinfo()
or you call it *first* when you need it, i.e. you check whether mntinfo_tree ==
NULL and if so call collect_mntinfo() on the corresponding ns_id.

> 
> > 
> > >  		mntns_root = mntns_get_root_fd(ns);
> > >  		if (mntns_root < 0) {
> > > 
> >