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Date:   Wed, 15 May 2019 20:40:32 -0400
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     Andreas Dilger <adilger@dilger.ca>
Cc:     Jeff Layton <jlayton@redhat.com>,
        "J. Bruce Fields" <bfields@redhat.com>,
        linux-nfs <linux-nfs@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org, abe@purdue.edu,
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Subject: Re: [PATCH 08/10] nfsd4: add file to display list of client's opens
Message-ID: <20190516004032.GA16284@fieldses.org>
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On Thu, Apr 25, 2019 at 09:18:04PM -0400, J. Bruce Fields wrote:
> On Thu, Apr 25, 2019 at 11:14:23PM +0200, Andreas Dilger wrote:
> > On Apr 25, 2019, at 10:14 PM, J. Bruce Fields <bfields@fieldses.org> wrote:
> > > 
> > > On Thu, Apr 25, 2019 at 02:04:59PM -0400, Jeff Layton wrote:
> > >> More bikeshedding: should we have a "states" file instead of an "opens"
> > >> file and print a different set of output for each stateid type?
> > > 
> > > Sure.  The format of the file could be something like
> > > 
> > > 	<stateid> open rw -- <openowner>...
> > > 	<stateid> lock r 0-EOF <lockowner>...
> > > 	<stateid> deleg r
> > > 
> > > I wonder if we could put owners on separate lines and do some
> > > heirarchical thing to show owner-stateid relationships?  Hm.  That's
> > > kind of appealing but more work.
> > 
> > My suggestion here would be to use YAML-formatted output rather than
> > space/tab separated positional fields.  That can still be made human
> > readable, but also machine parseable and extensible if formatted properly.
> 
> Well, anything we do will be machine-parseable.  But I can believe YAML
> would make future extension easier.  It doesn't look like it would be
> more complicated to generate.  It uses C-style escaping (like \x32) so
> there'd be no change to how we format binary blobs.
> 
> The field names make it a tad more verbose but I guess it's not too bad.

OK, I tried changing "opens" to "states" and using YAML.  Example output:

- 0x020000006a5fdc5c4ad09d9e01000000: { type: open, access: rw, deny: --, superblock: "fd:10:13649", owner: "open id:\x00\x00\x00&\x00\x00\x00\x00\x00\x0046��QH " }
- 0x010000006a5fdc5c4ad09d9e03000000: { type: open, access: r-, deny: --, superblock: "fd:10:13650", owner: "open id:\x00\x00\x00&\x00\x00\x00\x00\x00\x0046��QH" }
- 0x010000006a5fdc5c4ad09d9e04000000: { type: deleg, access: r, superblock: "fd:10:13650" }
- 0x010000006a5fdc5c4ad09d9e06000000: { type: lock, superblock: "fd:10:13649", owner: "lock id:\x00\x00\x00&\x00\x00\x00\x00\x00\x00\x00\x00" }

The parser Andreas suggested (https://yaml-online-parser.appspot.com/)
accepts these.  It also thinks strings are always in a unicode encoding
of some kind, which they aren't.  The owners are arbitrary series of
bytes but I'd like at least any ascii parts to be human readable, and
I'm a little stuck on how to do that.

--b.