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Subject: Re: shiftfs status and future development
From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Matthew Wilcox <willy@infradead.org>,
        Seth Forshee <seth.forshee@canonical.com>
Cc: containers@lists.linux-foundation.org,
        Tyler Hicks <tyler.hicks@canonical.com>,
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Date: Fri, 15 Jun 2018 09:09:15 -0700
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On Fri, 2018-06-15 at 08:25 -0700, Matthew Wilcox wrote:
> On Fri, Jun 15, 2018 at 09:59:17AM -0500, Seth Forshee wrote:
> >  - Supports any id maps possible for a user namespace
> 
> Have we already ruled out storing the container's UID/GID/perms in an
> extended attribute, and having all the files owned by the owner of
> the container from the perspective of the unshifted fs.  Then shiftfs
> reads the xattr and presents the files with the container's idea of
> what the UID is?

I've got an experimental patch set that does the *mark* as an xattr. 
However the shift is still done through s_userns, which allows for
multiple shifts.

James