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Date:   Thu, 1 Oct 2020 23:40:51 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Michael Ellerman <mpe@ellerman.id.au>, x86@kernel.org,
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        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 05/14] fs: don't allow kernel reads and writes without
 iter ops
Message-ID: <20201001224051.GI3421308@ZenIV.linux.org.uk>
References: <20200903142242.925828-1-hch@lst.de>
 <20200903142242.925828-6-hch@lst.de>
 <20201001223852.GA855@sol.localdomain>
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On Thu, Oct 01, 2020 at 03:38:52PM -0700, Eric Biggers wrote:

>  	mutex_lock(&sbi->pipe_mutex);
>  	while (bytes) {
> -		wr = __kernel_write(file, data, bytes, NULL);
> +		wr = __kernel_write(file, data, bytes, &file->f_pos);

Better
	loff_t dummy = 0;
...
		wr = __kernel_write(file, data, bytes, &dummy);