Re: [PATCH 2/2] ovl: allow distributed fs as lower layer

[Miklos Szeredi]

On Sun, Jun 7, 2015 at 3:02 AM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> A nasty corner case to be aware of (and I think this is part of what Al
> was warning about).  /proc/sys/net is different depending upon which
> current->nsproxy->net_ns.

Ah,  I'm beginning to grasp what's going on there: mulitple dentries
with the same name but belonging to different namespaces,
->d_compare() being used to select the right one.  Is that it?

Overlayfs checks for d_compare() on the root of the lower and upper
trees, but here it only set on a subdirectory of proc, not on every
dentry.  So overlayfs should be careful and check for
DCACHE_OP_COMPARE | DCACHE_OP_HASH and reject going down such a
dentry.


Thanks,
Miklos
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