[Virtio-fs] [PATCH] virtiofsd: Show submounts

[Dr. David Alan Gilbert]

* Dr. David Alan Gilbert (dgilbert at redhat.com) wrote:
> * Max Reitz (mreitz at redhat.com) wrote:
> > Currently, setup_mounts() bind-mounts the shared directory without
> > MS_REC.  This makes all submounts disappear.
> > 
> > Pass MS_REC so that the guest can see submounts again.
> 
> Thanks!
> 
> > Fixes: 3ca8a2b1c83eb185c232a4e87abbb65495263756
> 
> Should this actually be 5baa3b8e95064c2434bd9e2f312edd5e9ae275dc ?
> 
> > Signed-off-by: Max Reitz <mreitz at redhat.com>
> > ---
> >  tools/virtiofsd/passthrough_ll.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
> > index 4c35c95b25..9d7f863e66 100644
> > --- a/tools/virtiofsd/passthrough_ll.c
> > +++ b/tools/virtiofsd/passthrough_ll.c
> > @@ -2643,7 +2643,7 @@ static void setup_mounts(const char *source)
> >      int oldroot;
> >      int newroot;
> >  
> > -    if (mount(source, source, NULL, MS_BIND, NULL) < 0) {
> > +    if (mount(source, source, NULL, MS_BIND | MS_REC, NULL) < 0) {
> >          fuse_log(FUSE_LOG_ERR, "mount(%s, %s, MS_BIND): %m\n", source, source);
> >          exit(1);
> >      }
> 
> Do we want MS_SLAVE to pick up future mounts that might happenf rom the
> host?
> What's the interaction between this and the MS_REC|MS_SLAVE that we have
> a few lines above for / ?

Just to confirm something from vgoyal, and what had confused me about
why we hadn't spotted this earlier.

Even without this patch, the SLAVE stuff worked so if you start the
daemon and *then* mount under the shared directory, the guest sees it
with or without this patch.

However, without this patch you don't see a mount that was already there
before you start the daemon.

Dave

> Dave
> 
> > -- 
> > 2.25.3
> > 
> --
> Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK
--
Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK