Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 2 Dec 2020 18:14:16 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Eric Sandeen <sandeen@sandeen.net>
Cc:     ira.weiny@intel.com, fstests@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Chinner <david@fromorbit.com>,
        Christoph Hellwig <hch@lst.de>,
        "Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
        Jeff Moyer <jmoyer@redhat.com>, linux-ext4@vger.kernel.org,
        linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Eric Sandeen <sandeen@redhat.com>,
        David Howells <dhowells@redhat.com>
Subject: Re: [RFC PATCH] common/rc: Fix _check_s_dax() for kernel 5.10
Message-ID: <20201202171416.GA4268@lst.de>
References: <20201202160701.1458658-1-ira.weiny@intel.com> <b131a2a6-f02f-9a91-4de1-01a77b76577a@sandeen.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <b131a2a6-f02f-9a91-4de1-01a77b76577a@sandeen.net>
User-Agent: Mutt/1.5.17 (2007-11-01)
Precedence: bulk

On Wed, Dec 02, 2020 at 11:10:50AM -0600, Eric Sandeen wrote:
> xfstests gets used on distro kernels too, so relying on kernel version isn't
> really something we can use to make determinations like this, unfortunately.
> 
> Probably the best we can do is hope that the change makes it to stable and
> distro kernels quickly, and the old flag fades into obscurity.
> 
> Maybe worth a comment in the test mentioning the SNAFU, though, for anyone
> investigating it when it fails on older kernels?

I think we should explicitly check for the "old" or mixed up flag and
error out.  Given that the other meaning of the bit value should only
be set on mount points it should be easy to test.  That means we will
reliably fail on old and distro kernels, but I think that is the right
thing to do in this case.