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Date:   Thu, 28 May 2020 20:00:52 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Ian Kent <raven@themaw.net>,
        David Howells <dhowells@redhat.com>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        netfilter-devel@vger.kernel.org
Subject: Re: [PATCH 09/14] fs: don't change the address limit for
 ->write_iter in __kernel_write
Message-ID: <20200528190052.GM23230@ZenIV.linux.org.uk>
References: <20200528054043.621510-1-hch@lst.de>
 <20200528054043.621510-10-hch@lst.de>
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On Thu, May 28, 2020 at 07:40:38AM +0200, Christoph Hellwig wrote:
> If we write to a file that implements ->write_iter there is no need
> to change the address limit if we send a kvec down.  Implement that
> case, and prefer it over using plain ->write with a changed address
> limit if available.

Umm...  It needs a comment along the lines of "weird shits like
/dev/sg that currently check for uaccess_kernel() will just
have to make sure they never switch to ->write_iter()"