linux-ext4 - Re: [PATCH v3 1/1] xfstests: generic/403: reproduce ext4 bugs in a shift extents logic

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Date:   Thu, 12 Jan 2017 12:08:20 +0800
From:   Eryu Guan <eguan@...hat.com>
To:     Roman Pen <roman.penyaev@...fitbricks.com>
Cc:     "Theodore Ts'o" <tytso@....edu>, linux-ext4@...r.kernel.org,
        fstests@...r.kernel.org
Subject: Re: [PATCH v3 1/1] xfstests: generic/403: reproduce ext4 bugs in a
 shift extents logic

On Wed, Jan 11, 2017 at 10:52:39AM +0100, Roman Pen wrote:
> Regression test which targets two nasty ext4 bugs in a logic which
> shifts extents:
> 
> 1) 14d981f468a1 ("ext4: Include forgotten start block on fallocate insert range")
> 
> Test tries to insert many blocks at the same offset to reproduce
> the following layout on ext4:
> 
>    block #0  block #1
>    |ext0 ext1|ext2 ext3 ...|
>         ^
>      insert of a new block
> 
> Because of an incorrect range first block is never reached,
> thus ext1 is untouched, resulting to a hole at a wrong offset:
> 
> What we got:
> 
>    block #0   block #1
>    |ext0 ext1|   ext2 ext3 ...|
>               ^
>               hole at a wrong offset
> 
> What we expect:
> 
>    block #0    block #1
>    |ext0   ext1|ext2 ext3 ...|
>         ^
>         hole at a correct offset
> 
> 2) 2b3864b32403 ("ext4: do not polute the extents cache while shifting extents")
> 
> Extents status tree is filled in with outdated offsets while doing
> extent shift, that leads to wrong data blocks.   That's why md5sum
> of a result file is being checked after each block insert.

Thanks a lot! I did a minor update and queued it up.

> 
> Signed-off-by: Roman Pen <roman.penyaev@...fitbricks.com>
> Cc: "Theodore Ts'o <tytso@....edu>"
> Cc: Eryu Guan <eguan@...hat.com>
> Cc: linux-ext4@...r.kernel.org
> Cc: fstests@...r.kernel.org
> ---

> +# Modify as appropriate.
> +_supported_fs generic
> +_supported_os Linux
> +_require_test
> +_require_xfs_io_command "finsert"
> +
> +blksize=`get_block_size $TEST_DIR`

I merged a patch earlier from Darrick to rename get_block_size to
_get_block_size. So I did the rename here too.

Thanks,
Eryu
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