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Date:   Thu, 15 Apr 2021 07:54:08 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Theodore Ts'o <tytso@mit.edu>
Cc:     Christian Brauner <christian.brauner@ubuntu.com>,
        Eryu Guan <guan@eryu.me>,
        Christian Brauner <brauner@kernel.org>,
        fstests@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
        linux-ext4@vger.kernel.org, "Darrick J . Wong" <djwong@kernel.org>,
        David Howells <dhowells@redhat.com>,
        Amir Goldstein <amir73il@gmail.com>
Subject: Re: [PATCH -RFC] ext4: add feature file to advertise that ext4
 supports idmapped mounts
Message-ID: <20210415055408.GA8947@lst.de>
References: <20210328223400.1800301-3-brauner@kernel.org> <YHMH/JRmzg3ETcED@desktop> <20210411151249.6y34x7yatqtpcvi6@wittgenstein> <20210411151857.wd6gd46u53vlh2xv@wittgenstein> <YHMUAL/oD4fB3+R7@desktop> <20210411153223.vhcegiklrwoczy55@wittgenstein> <YHOW7DN51YuYgLPM@mit.edu> <20210412115426.a4bzsx4cp7jhx2ou@wittgenstein> <YHTMkBcVTFAGqyks@mit.edu> <YHdUzqZ7PZtb64zf@mit.edu>
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On Wed, Apr 14, 2021 at 04:47:10PM -0400, Theodore Ts'o wrote:
> On Mon, Apr 12, 2021 at 06:41:20PM -0400, Theodore Ts'o wrote:
> > In the ideal world, if the kernel wasn't compiled with the necessary
> > CONFIG options enabled, it's desirable of the test can detect that
> > fact and skip running the test instead failing and forcing the person
> > running the test to try to figure out whether this is a legitmate file
> > system bug or a just a test setup bug.
> 
> So it would make it easier for me to manage running xfstests on ext4
> if I had added something like this to ext4 and sent it to Linus before
> v5.12 is released.  What do folks think?

Completely stupid.  This is a VFS-level feature and we need to have
proper VFS-level testing (which we have through creating a mount
with the option), not fs-specific band aids.