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Subject: Re: restore splice and sendfile support on kernfs
To:     Christoph Hellwig <hch@lst.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Tejun Heo <tj@kernel.org>
CC:     Siddharth Gupta <sidgup@codeaurora.org>,
        <linux-kernel@vger.kernel.org>
References: <20210120204631.274206-1-hch@lst.de>
From:   Robert Karszniewicz <r.karszniewicz@phytec.de>
Message-ID: <5a13228c-6003-2499-a987-23d39f1926cf@phytec.de>
Date:   Thu, 21 Jan 2021 18:41:35 +0100
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On 1/20/21 9:46 PM, Christoph Hellwig wrote:
> Hi Greg and Tejun,
> 
> this fixes a regression in Linux 5.10 that stopped sendfile and splice
> from working on kernfs/sysfs files.
> 
> Diffstt:
>  file.c |   65 ++++++++++++++++++++++++-----------------------------------------
>  1 file changed, 24 insertions(+), 41 deletions(-)
> 

Tested-by: Robert Karszniewicz <r.karszniewicz@phytec.de>

Confirm that it fixes firmwared for me.

Also, I am 100% sure that the commit that actually breaks firmwared for me is
4d03e3cc5982 ("fs: don't allow kernel reads and writes without iter ops")
which is one commit right before
36e2c7421f02 ("fs: don't allow splice read/write without explicit ops")
. I just verified it again.

Thank you,
Robert