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Date:   Mon, 24 Aug 2020 08:13:45 +0800
From:   Murphy Zhou <jencce.kernel@gmail.com>
To:     Trond Myklebust <trondmy@hammerspace.com>
Cc:     "fllinden@amazon.com" <fllinden@amazon.com>,
        "jencce.kernel@gmail.com" <jencce.kernel@gmail.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "anna.schumaker@netapp.com" <anna.schumaker@netapp.com>
Subject: Re: [PATCH v3 12/13] NFSv4.2: hook in the user extended attribute
 handlers
Message-ID: <20200824001345.nszimqfcsumd4xil@xzhoux.usersys.redhat.com>
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 <20200821160338.GA30541@dev-dsk-fllinden-2c-c1893d73.us-west-2.amazon.com>
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On Fri, Aug 21, 2020 at 04:41:04PM +0000, Trond Myklebust wrote:
> On Fri, 2020-08-21 at 16:03 +0000, Frank van der Linden wrote:
> > On Fri, Aug 21, 2020 at 02:50:59PM +0800, Murphy Zhou wrote:
> > > Hi,
> > > 
> > > On Wed, Jun 24, 2020 at 6:51 AM Frank van der Linden
> > > <fllinden@amazon.com> wrote:
> > [...]
> > > >  static const struct inode_operations nfs4_dir_inode_operations =
> > > > {
> > > > @@ -10146,10 +10254,21 @@ static const struct xattr_handler
> > > > nfs4_xattr_nfs4_acl_handler = {
> > > >         .set    = nfs4_xattr_set_nfs4_acl,
> > > >  };
> > > > 
> > > > +#ifdef CONFIG_NFS_V4_2
> > > > +static const struct xattr_handler nfs4_xattr_nfs4_user_handler =
> > > > {
> > > > +       .prefix = XATTR_USER_PREFIX,
> > > > +       .get    = nfs4_xattr_get_nfs4_user,
> > > > +       .set    = nfs4_xattr_set_nfs4_user,
> > > > +};
> > > > +#endif
> > > > +
> > > 
> > > Any plan to support XATTR_TRUSTED_PREFIX ?
> > > 
> > > Thanks.
> > 
> > This is an implementation of RFC 8276, which explicitly restricts
> > itself
> > to the "user" namespace.
> > 
> > There is currently no portable way to implement the "trusted"
> > namespace
> > within the boundaries of the NFS specification(s), so it's not
> > supported.
> > 
> 
> Correct. 'trusted' is just another way to implement private protocols.
> Those are unacceptable in a shared filesystem environment.

Thank you guys explanation!

I'm asking because after NFSv4.2 xattr update, there are some xfstests
new failures about 'trusted' xattr. Now they can be surely marked as
expected.

> 
> -- 
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com
> 
> 

-- 
Murphy