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Date:   Mon, 10 Dec 2018 12:17:29 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>, Todd Aiken <taiken@mvtech.ca>,
        Keith Busch <keith.busch@intel.com>,
        Laurence Oberman <loberman@redhat.com>, stable@vger.kernel.org
Subject: Re: [PATCH] block: Restore tape support
Message-ID: <20181210111729.GA21553@lst.de>
References: <20181210030814.13235-1-bvanassche@acm.org>
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On Sun, Dec 09, 2018 at 07:08:14PM -0800, Bart Van Assche wrote:
> According to what I found in
> https://bugzilla.kernel.org/show_bug.cgi?id=201935 patch "block: Clear
> kernel memory before copying to user" broke tape access. Hence revert
> that patch.

This looks wrong.  The patch from Keith is obviously correct for
normal usage of bio_copy_user_iov.  The SCSI tape drivers use the
somewhat odd null_mapped case, so we probably need to refine the checks
for that a bit.