[CRIU] [PATCH 5/9] mounts: handle bind-mounts

[Andrew Vagin]

On Tue, Jul 09, 2013 at 08:41:34PM +0400, Pavel Emelyanov wrote:
> On 07/09/2013 03:05 PM, Andrey Vagin wrote:
> > A non-root mount is bind-mounted to a proper root mount.
> > 
> > Non-root mount without root mount is not supported yet
> > 
> > Signed-off-by: Andrey Vagin <avagin at openvz.org>
> > ---
> >  include/proc_parse.h |  2 ++
> >  mount.c              | 75 +++++++++++++++++++++++++++++++++++++---------------
> >  2 files changed, 55 insertions(+), 22 deletions(-)
> > 
> > diff --git a/include/proc_parse.h b/include/proc_parse.h
> > index 99255c4..1325424 100644
> > --- a/include/proc_parse.h
> > +++ b/include/proc_parse.h
> > @@ -114,9 +114,11 @@ struct mount_info {
> >  
> >  	/* tree linkage */
> >  	struct mount_info *parent;
> > +	struct mount_info *bind;
> >  	struct list_head children;
> >  	struct list_head siblings;
> >  
> > +	struct list_head mnt_bind;
> 
> Document the fields please.
> 
> >  	struct list_head mnt_share;	/* circular list of shared mounts */
> >  	struct list_head mnt_slave_list;/* list of slave mounts */
> >  	struct list_head mnt_slave;	/* slave list entry */
> > diff --git a/mount.c b/mount.c
> > index 640cd12..31b1f3c 100644
> > --- a/mount.c
> > +++ b/mount.c
> > @@ -77,6 +77,16 @@ struct mount_info *lookup_mnt_sdev(unsigned int s_dev)
> >  	return NULL;
> >  }
> >  
> > +/* two bind-mounts are reported as equal if bind is true */
> > +static bool mntcmp(struct mount_info* mi, struct mount_info *c, bool bind)
> > +{
> > +	return (mi->s_dev == c->s_dev &&
> > +		(bind || !strcmp(c->root, mi->root)) &&
> 
> I see no callers of these with bind == true. Where is it?

in the next patches

> 
> > +		!strcmp(c->source, mi->source) &&
> > +		!strcmp(c->options, mi->options) &&

...
> > +
> > +		/* Search bind-mounts */
> > +		if (list_empty(&m->mnt_bind))
> > +			for (t = m->next; t; t = t->next) {
> > +				if (mntcmp(m, t, true))
> > +					list_add(&t->mnt_bind, &m->mnt_bind);
> 
> I don't understand what the mnt_bind list links together.

It links together all mounts, which are the same except root. Only one
of them must be mounted and all other can be bind-mounted

> 
> > +			}
> >  	}
> >  
> >  	return 0;
> > @@ -432,16 +465,6 @@ static struct fstype *decode_fstype(u32 fst)
> >  	return &fstypes[fst];
> >  }
> >