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From:   Steve French <smfrench@gmail.com>
Date:   Sat, 9 Feb 2019 15:49:17 -0600
Message-ID: <CAH2r5mt5wzqKMa3gh_n2KaOORzCj+rkFQh2kCdbDTMBVax3v8A@mail.gmail.com>
Subject: Re: [LSF/MM TOPIC] Containers and distributed filesystems
To:     Trond Myklebust <trondmy@hammerspace.com>
Cc:     "lsf-pc@lists.linux-foundation.org" 
        <lsf-pc@lists.linux-foundation.org>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        samba-technical <samba-technical@lists.samba.org>,
        CIFS <linux-cifs@vger.kernel.org>
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Trond's proposal for discussion (his proposal below) at LSF/MM makes
sense and could be useful, and similar questions come up often with
CIFS/SMB3 (and probably other distributed file systems).

On Wed, Jan 23, 2019 at 12:11 PM Trond Myklebust
<trondmy@hammerspace.com> wrote:
> I'd like to propose an LSF/MM discussion around the topic of containers
> and distributed filesystems.
>
> The background is that we have a number of decisions to make around
> dealing with namespaces when the filesystem is distributed.
>
> On the one hand, there is the issue of which user namespace we should
> be using when putting uids/gids on the wire, or when translating into
> alternative identities (user/group name, cifs SIDs,...). There are two
> main competing proposals: the first proposal is to select the user
> namespace of the process that mounted the distributed filesystem. The
> second proposal is to (continue to) use the user namespace pointed to
> by init_nsproxy. It seems that whichever choice we make, we probably
> want to ensure that all the major distributed filesystems (AFS, CIFS,
> NFS) have consistent handling of these situations.
> Another issue arises around the question of identifying containers when
> they are migrated. At least the NFSv4 client needs to be able to send a
> unique identifier that is preserved across container migration. The
> uts_namespace is typically insufficient for this purpose, since most
> containers don't bother to set a unique hostname.

Makes sense

> Finally, there is an issue that may be unique to NFS (in which case I'd
> be happy to see it as a hallway discussion or a BoF session) around
> preserving file state across container migrations.

Not unique to NFS


-- 
Thanks,

Steve