[overlayfs/bug] LXC ephemeral containers have "/rootfs" prefix in /proc/self/maps entries

[Andy Whitcroft]

On Tue, Aug 27, 2013 at 05:30:35PM +0800, Li Jianguo wrote:
> This is a design resolution. Linux kernel v3.0 or higher has fix it.
> Here is our overlayfs patch for HREL kernel v2.6.32. We just modify
> d_path() in fs/dcache.c. It seems work!

The attached patch seems to be the whole of overlayfs, but assuming it
is just the changes in dcache then the patch seems similar to upstream.
That said this is a fairly scarey change to be applying in SRU as it
does impact the dcache.

We have considered fixing this before and the decision there was that
though it is unfortuanate that this prefix is exposed, it is pretty easy
to work round in the normal case, using a symlink in the guest filesystem
namespace.  Fixing the use cases we had considered.

-apw