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Date:   Fri, 21 Dec 2018 07:53:54 -0800
From:   Matthew Wilcox <willy@infradead.org>
To:     "Theodore Y. Ts'o" <tytso@mit.edu>,
        Christoph Hellwig <hch@infradead.org>,
        Dave Chinner <david@fromorbit.com>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Eric Biggers <ebiggers@kernel.org>,
        linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        Victor Hsieh <victorhsieh@google.com>,
        Chandan Rajendra <chandan@linux.vnet.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2 01/12] fs-verity: add a documentation file
Message-ID: <20181221155354.GC10600@bombadil.infradead.org>
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On Fri, Dec 21, 2018 at 10:47:14AM -0500, Theodore Y. Ts'o wrote:
> Linus --- we're going round and round, and I don't think this is
> really a technical dispute at this point, but rather an aesthetics
> one.  Will you be willing to accept my pull request for a feature
> which is being shippped on millions of Android phones, has been out
> for review for months, and for which, if we *really* need to add
> uselessly complicated interface later, we can do that?  It's always
> been the case for internal Kernel interfaces not to add code "just in
> case" it's useful, but rather when a user turns up.  I argue we should
> be doing the same thing for user-space visible interfaces.

To look at it another way, this is an aesthetic dispute in which all those
who have offered opinions from outside Google -- myself, Dave Chinner &
Christoph all really dislike this interface.  I'd be happy to discuss
alternative interfaces, particularly ones which allow for the current
internal implementation, but I think this interface is really bad.

In contrast to "we'll just fix it up later" (which usually applies
to in-kernel interfaces), we have a policy of not breaking userspace,
so accepting this interface means setting it in stone.  We should get
it right.