linux-ext4 - Re: [PATCH] ext4: add regression tests for ^extents punch hole

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Date:	Mon, 23 Feb 2015 17:28:23 -0600
From:	Eric Sandeen <sandeen@...deen.net>
To:	Omar Sandoval <osandov@...ndov.com>,
	Dave Chinner <david@...morbit.com>
CC:	fstests@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: add regression tests for ^extents punch hole

On 2/23/15 5:11 PM, Omar Sandoval wrote:
> On Tue, Feb 24, 2015 at 09:46:20AM +1100, Dave Chinner wrote:
>> On Mon, Feb 23, 2015 at 02:39:36PM -0800, Omar Sandoval wrote:
>>> Linux commit 6f30b7e37a82 (ext4: fix indirect punch hole corruption)
>>> fixes several bugs in the FALLOC_FL_PUNCH_HOLE implementation for an
>>> ext4 filesystem with indirect blocks.
>>>
>>> Signed-off-by: Omar Sandoval <osandov@...ndov.com>
>>> ---
>>>  tests/ext4/005     | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>  tests/ext4/005.out |  29 ++++++++++++++
>>>  tests/ext4/group   |   1 +
>>>  3 files changed, 145 insertions(+)
>>>  create mode 100755 tests/ext4/005
>>>  create mode 100644 tests/ext4/005.out
>>
>> What's ext4 specific about this test apart from the mkfs parameter?
>> Shouldn't it be generic and so test all the filesystems behave the
>> same?  i.e. when someone then runs
>>
>> # MKFS_OPTIONS="-b size=1k -O ^extents" ./check -g auto
>>
>> That will exercise this specific regression fix, not to mention give
>> much, much better test coverage of that configuration than just
>> making a single test use that config...
>>
>> Cheers,
>>
>> Dave.
>> -- 
>> Dave Chinner
>> david@...morbit.com
> 
> Hi, Dave,
> 
> This test isn't completely generic bcause the output is dependent on the
> block size. In particular, fpunch+fiemap will have different results
> based on the block size:
> 
> ----
> # mkfs.ext3 -b1024 /dev/sdb1
> # mount /dev/sdb1 /mnt/test
> # xfs_io -f -c 'pwrite 0 8192' /mnt/test/a
> # xfs_io -c 'fpunch 0 1024' /mnt/test/a
> # xfs_io -c fiemap /mnt/test/a
> /mnt/test/a:
>         0: [0..1]: hole
>         1: [2..15]: 1028..1041
> # umount /mnt/test
> # mkfs.ext3 -b4096 /dev/sdb1
> # mount /dev/sdb1 /mnt/test
> # xfs_io -f -c 'pwrite 0 8192' /mnt/test/a
> # xfs_io -c 'fpunch 0 1024' /mnt/test/a
> # xfs_io -c fiemap /mnt/test/a
> /mnt/test/a:
>         0: [0..15]: 8192..8207
> ----
> 
> I could either remove the fiemap output from the test case and rely on
> the md5sum or round all of the punches to some larger block size so it
> will behave the same up to, say, 8k. Do either of those options sound
> better?
> 
> Alternatively, is there a good way to have block size-dependent test
> output? Then we could have the test adapt to different block sizes and
> cover these regressions at any block size, not just 1k.

Can you scale every operational offset by block size?  I think there are
other tests which do this sort of thing - look at _filter_bmap in test
xfs/194 maybe?

i.e. above you would do 'fpunch 0 $blocksize' not 'fpunch 0 1024'
(or blocksize/4, or whatever your intent is)

-Eric

> Thanks!
> 

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