Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 21 Feb 2018 10:56:45 -0500
From:   Theodore Ts'o <tytso@mit.edu>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Tommi Rantala <tommi.t.rantala@nokia.com>,
        Tahsin Erdogan <tahsin@google.com>,
        Andreas Dilger <adilger@dilger.ca>, linux-ext4@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: backporting "ext4: inplace xattr block update fails to
 deduplicate blocks" to LTS kernels?
Message-ID: <20180221155644.GC9900@thunk.org>
Mail-Followup-To: Theodore Ts'o <tytso@mit.edu>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Tommi Rantala <tommi.t.rantala@nokia.com>,
        Tahsin Erdogan <tahsin@google.com>,
        Andreas Dilger <adilger@dilger.ca>, linux-ext4@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
References: <f3db4b3f-9cb6-c96c-8d31-f2a5f8b4082c@nokia.com>
 <20180221114000.GB6555@kroah.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180221114000.GB6555@kroah.com>
User-Agent: Mutt/1.9.3 (2018-01-21)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Feb 21, 2018 at 12:40:00PM +0100, Greg Kroah-Hartman wrote:
> On Mon, Feb 19, 2018 at 03:26:37PM +0200, Tommi Rantala wrote:
> > 
> > OK to backport it?
> > I tested it briefly in 4.9, seems to work.

It looks sane, but it would be nice if I can get people who are
backporting ext4 patches to make sure there are no regressions using
one of kvm-xfstests[1] or gce-xfstests[2][3].....

[1] https://github.com/tytso/xfstests-bld/blob/master/Documentation/kvm-xfstests.md
[2] https://github.com/tytso/xfstests-bld/blob/master/Documentation/gce-xfstests.md
[3] https://thunk.org/gce-xfstests

I do run regression tests[4] on stable kernels when I have time, but
it scales much better when other people can help.

[4] https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/tag/?h=ext4-4.9.54-1

> I need an ack from the ext4 maintainers before I can take this...

Greg, you can go ahead and take this, but in the future I'd appreciate
it if ext4 backporters could at least run a smoke test (which takes
less than 15 minutes on GCE) before and after the patch, and report no
test regressions.

More aggressive testers can and should run "{kvm,gce}-xfstests auto"
which take overnight, and the really adventurous can use the
lightweight test manager (ltm) which will break up the test run the
job across multiple VM's and do the job in about 2.5 hours or so.  :-)

		      	     	     - Ted