Re: [Lsf-pc] [LSF/MM ATTEND] FS jitter testing, network caching, Lustre, cluster filesystems.

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Mon, 2017-01-16 at 13:02 -0500, Oleg Drokin wrote:
> On Jan 16, 2017, at 12:32 PM, James Bottomley wrote:
> 
> > On Sun, 2017-01-15 at 18:38 -0500, Oleg Drokin wrote:
> > >   A container support from filesystems is also very relevant to
> > > us 
> > > since Lustre    is used more and more in such settings.
> > 
> > I've added the containers ML to the cc just in case.  Can you add
> > more
> > colour to this, please?  What container support for filesystems do
> > you
> > think we need beyond the user namespace in the superblock?
> 
> Namespace access is necessary, we might need it before the superblock 
> is there too (say during mount we might need kerberos credentials 
> fetched to properly authenticate this mount instance to the server).

The superblock namespace is mostly for uid/gid changes across the
kernel <-> filesystem boundary.

The actual container namespaces will already be set up by the time the
mount is done (assuming mount within a container), so you have them all
present.  Usually you get the information for credentials from a
combination of the UTS namespace (host/domain name) and the mount
namespace (credentials provisioned to container filesystem).

Perhaps if you described the actual problem you're seeing rather than
try to relate it to what I said about superblock namespace (which is
probably irrelevant), we could figure out what the issue is.

James