linux-ext4 - Re: [PATCH] xfstests 240: test non-aligned AIO hole-filling

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Date:	Thu, 22 Jul 2010 22:32:29 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Dave Chinner <david@...morbit.com>
CC:	xfs-oss <xfs@....sgi.com>,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] xfstests 240: test non-aligned AIO hole-filling

Dave Chinner wrote:

> On Thu, Jul 22, 2010 at 02:05:26PM -0500, Eric Sandeen wrote:
>   
>> This replicates file corruption we've seen with qemu-kvm when
>> we use if=virtio,cache=none,aio=native for IO to a sparse
>> ext4- or xfs-hosted file, and the partitions/filesystems
>> within that file image are not block-aligned.  (think sector
>> 63 here...)  This results in AIO IOs not aligned to the
>> filesystem blocks.
>>
>> This test modifies aiodio_sparse2.c to add an option to start
>> the file IO at an offset.
>>
>> When we do 4k writes to a 16k file in 2 threads, starting
>> at offset 512, we get 0s interspersed in the file where they
>> should not be:
>>
>> 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
>> *
>> 00000200  01 01 01 01 01 01 01 01  01 01 01 01 01 01 01 01  |................|
>> *
>> 00001000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
>> *
>> 00001200  01 01 01 01 01 01 01 01  01 01 01 01 01 01 01 01  |................|
>> ....
>>
>> Signed-off-by: Eric Sandeen <sandeen@...deen.net>
>>     
>
> looks good - it needs to remove the $TEST_DIR/aiodio_sparse file
> before the test starts, though, so that repeated tests fail
> correctly. Otherwise:
>
>   
hm, but:

+rm -f "$TEST_DIR/aiodio_sparse*"
+
+# 2 threads, 4k writes, 16k filesize, stride throug file by 4k, start at 512 offset
+$here/src/aio-dio-regress/aiodio_sparse2 -i 2 -w 4k -s 16k -n 4k -o 512 "$TEST_DIR/aiodio_sparse"

It does remove it ... no?


> Reviewed-by: Dave Chinner <dchinner@...hat.com>
>
>   
thanks

> Also, Eric, can you run this proof-of-concept test branch (on top of
> the current XFS for-2.6.36 branch) and see if QEMU is happy with it?
> It passes this test on my machine....
>
>   
Absolutely, thanks!

-Eric

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