Date: Wed, 19 Jan 2005 04:31:51 +0200
From: Sami Farin <7atbggg02@sneakemail.com>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH - 2.6.10] generic_file_buffered_write handle partial DIO writes with multiple iovecs
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On Tue, Jan 18, 2005 at 05:22:44PM -0800, Daniel McNeil wrote:
> Andrew,
> 
> This is a patch to generic_file_buffered_write() to correctly
> handle partial O_DIRECT writes (because of unallocated blocks)
> when there is more than 1 iovec.  Without this patch, the code is
> writing the wrong iovec (it writes the first iovec a 2nd time).
> 
> Included is a test program dio_bug.c that shows the problem by:
> 	writing 4k to offset 4k
> 	writing 4k to offset 12k
> 	writing 8k to offset 4k
> The result is that 8k write writes the 1st 4k of the buffer twice.
> 
> $ rm f; ./dio_bug f
> wrong value offset 8k expected 0x33 got 0x11
> wrong value offset 10k expected 0x44 got 0x22
> 
> with patch
> $ rm f; ./dio_bug f

I have Linux 2.6.10-ac9 + bio clone memory corruption -patch,
and dio_bug does not give errors (without your patch).

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