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Date:   Wed, 3 Feb 2021 11:31:28 -0500
From:   "Theodore Ts'o" <tytso@mit.edu>
To:     Andreas Dilger <adilger@dilger.ca>
Cc:     Daniel Rosenberg <drosen@google.com>,
        Eric Biggers <ebiggers@kernel.org>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        Gabriel Krisman Bertazi <krisman@collabora.com>,
        kernel-team@android.com, Paul Lawrence <paullawrence@google.com>
Subject: Re: [PATCH 1/2] ext4: Handle casefolding with encryption
Message-ID: <YBrP4NXAsvveIpwA@mit.edu>
References: <20210203090745.4103054-2-drosen@google.com>
 <56BC7E2D-A303-45AE-93B6-D8921189F604@dilger.ca>
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On Wed, Feb 03, 2021 at 03:55:06AM -0700, Andreas Dilger wrote:
> 
> It looks like this change will break the dirdata feature, which is similarly
> storing a data field beyond the end of the dirent. However, that feature also
> provides for flags stored in the high bits of the type field to indicate
> which of the fields are in use there.
> The first byte of each field stores
> the length, so it can be skipped even if the content is not understood.

Daniel, for context, the dirdata field is an out-of-tree feature which
is used by Lustre, and so has fairly large deployed base.  So if there
is a way that we can accomodate not breaking dirdata, that would be
good.

Did the ext4 casefold+encryption implementation escape out to any
Android handsets?

Thanks,

					- Ted