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    SubjectRe: [PATCH v4 0/3] random: convert to using iters, for Al Viro
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    On 5/20/22 9:47 AM, Al Viro wrote:
    > On Fri, May 20, 2022 at 09:34:46AM -0600, Jens Axboe wrote:
    >
    >> I'm very sure, otherwise we're just accepting that we're breaking real
    >> world applications.
    >
    > "Breaking" as in "it used to work with earlier kernels, doesn't work with
    > recent ones"? Details, please...

    Yes, as in exactly that. This is what drove this addition of
    ->read_iter() for urandom. See commit:

    ommit 36e2c7421f02a22f71c9283e55fdb672a9eb58e7
    Author: Christoph Hellwig <hch@lst.de>
    Date: Thu Sep 3 16:22:34 2020 +0200

    fs: don't allow splice read/write without explicit ops

    related to the set_fs() changes, and now go look for any commit that
    has:

    Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops")

    in it and see that this isn't an isolated incident at all.

    tldr - splice from /dev/urandom used to work, and I recently got a
    report internally on an application that broke on upgrade from 5.6 to
    5.12 exactly because it now just just -EINVAL's instead.

    --
    Jens Axboe

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