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Date:   Mon, 14 Jan 2019 18:58:57 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Andreas =?iso-8859-1?Q?Gr=FCnbacher?= 
        <andreas.gruenbacher@gmail.com>
Cc:     Christoph Hellwig <hch@lst.de>,
        Carlos Maiolino <cmaiolino@redhat.com>,
        Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
        Andreas Dilger <adilger@dilger.ca>, sandeen@redhat.com,
        Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH 00/10 V2] New ->fiemap infrastructure and ->bmap removal
Message-ID: <20190114175857.GA8634@lst.de>
References: <20181205091728.29903-1-cmaiolino@redhat.com> <CAHpGcM+9ZwsDBRgJYpqwg3_aw5o71T3ARF6JqJG0ziRWQKA-_A@mail.gmail.com> <20181207093429.t3zzkxmfc4wlt5ny@hades.usersys.redhat.com> <20190114165023.GB7187@lst.de> <CAHpGcMK5wyLYRxVC9rtVgZ9SrP7XzSVyb78er4U3QD-RaMM1tQ@mail.gmail.com>
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On Mon, Jan 14, 2019 at 06:56:16PM +0100, Andreas Grünbacher wrote:
> Yes, locking. The fiemap_fill_cb callback hack still makes the fiemap
> interface much uglier though. So couldn't the existing iop be used to
> fill a kernel buffer in a way similar to what functions like
> kernel_readv do? That would at least avoid wrecking an existing
> interface.

There is no file system visible change at all, the callback happens
all behind the back.  We could do a less extensible union based version,
but I see absolutely no upside in that.

set_fs as in kernel_readv needs to go away, so no new users should be
added.