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Date:   Sat, 27 Apr 2019 15:00:38 -0400
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     NeilBrown <neilb@suse.com>
Cc:     Andreas Dilger <adilger@dilger.ca>,
        "J. Bruce Fields" <bfields@redhat.com>,
        linux-nfs <linux-nfs@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>, abe@purdue.edu,
        lsof-l@lists.purdue.edu, util-linux@vger.kernel.org,
        Jeff Layton <jlayton@redhat.com>,
        James Simmons <uja.ornl@gmail.com>
Subject: Re: [PATCH 00/10] exposing knfsd opens to userspace
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On Sat, Apr 27, 2019 at 09:55:23AM +1000, NeilBrown wrote:
> On Fri, Apr 26 2019, J. Bruce Fields wrote:
> > But it's true that from the start nfsd didn't really fit the model
> > of a single (possibly writeable) attribute per file.
> 
> Depends on what you mean by that.  Original files where write-only and
> where slightly complex attributes.

Yes I thought it was just those too, but then I looked at the original
commit it also included at least the "exports" file.

> Writing performed an action, like
> adding an entry to the export table (first you add a client, then add a
> client+filesystem to export it).
> 
> This idea for a file performing an action, rather than presenting an
> attribute, is much the same as the "bind" and "unbind" files you can
> find in sysfs.
> 
> (see also https://lwn.net/Articles/378884/ for examples of sysfs files
> that are not one-attribute-per-file)

I'll give that a re-read, thanks.

I did spend maybe a few minutes looking into basing nfsd code on kernfs
and didn't think it was worth it.  I could take a more serious look.

--b.