linux-ext4 - Re: [PATCHv2 5/9] generic/031: Fix the test case for 64k blocksize config

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Date:   Sun, 8 Aug 2021 20:36:11 +0800
From:   Eryu Guan <guan@...u.me>
To:     Ritesh Harjani <riteshh@...ux.ibm.com>
Cc:     fstests@...r.kernel.org, linux-ext4@...r.kernel.org,
        Theodore Ts'o <tytso@....edu>,
        "Darrick J . Wong" <djwong@...nel.org>,
        Dave Chinner <david@...morbit.com>
Subject: Re: [PATCHv2 5/9] generic/031: Fix the test case for 64k blocksize
 config

On Tue, Aug 03, 2021 at 10:30:33AM +0530, Ritesh Harjani wrote:
> On 21/08/02 12:00AM, Eryu Guan wrote:
> > On Wed, Jul 21, 2021 at 10:57:58AM +0530, Ritesh Harjani wrote:
> > > This test fails with blocksize 64k since the test assumes 4k blocksize
> > > in fcollapse param. This patch fixes that and also tests for 64k
> > > blocksize.
> > >
> > > Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>
> > > ---
> > >  tests/generic/031     | 14 +++++++++-----
> > >  tests/generic/031.out | 16 ++++++++--------
> > >  2 files changed, 17 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/tests/generic/031 b/tests/generic/031
> > > index 313ce9ff..11961c54 100755
> > > --- a/tests/generic/031
> > > +++ b/tests/generic/031
> > > @@ -26,11 +26,16 @@ testfile=$SCRATCH_MNT/testfile
> > >  _scratch_mkfs > /dev/null 2>&1
> > >  _scratch_mount
> > >
> > > +# fcollapse need offset and len to be multiple of blocksize for filesystems
> > > +# So let's make the offsets and len required for fcollapse multiples of 64K
> > > +# so that it works for all configurations (including on dax on 64K page size
> > > +# systems)
> > > +fact=$((65536/4096))
> > >  $XFS_IO_PROG -f \
> > > -	-c "pwrite 185332 55756" \
> > > -	-c "fcollapse 28672 40960" \
> > > -	-c "pwrite 133228 63394" \
> > > -	-c "fcollapse 0 4096" \
> > > +	-c "pwrite $((185332*fact + 12)) $((55756*fact + 12))" \
> >
> > Where does this 12 come from?
> A random number so that the offset and length are not bocksize aligned.
> If you see the final .out file, you will see the offset of the writes
> remains the same with and before this patch.
> 
> > And I'm wondering if this still reproduces the original bug.
> I am not sure how to trigger this. I know that this test was intended for
> bs < ps cases. If someone can help me / point me to the kernel fix for this,
> I can try to reproduce the original bug too.
> 
> I found this link for this test patch series. Couldn't find the kernel fixes
> link though.
> https://www.spinics.net/lists/fstests/msg00340.html

I think it's a regression test for this patchset.

https://www.spinics.net/lists/xfs/msg29807.html

> 
> 
> >
> > And looks like that the original test setups came from a specific
> > fsstress or fsx run, and aimed to the specific bug, perhaps we could
> > require the test with <= 4k block size, and _notrun in 64k case.
> 
> It would be good to know whether this code could trigger the original bug or
> not. Then we need not make _notrun for 64k case.

Agreed, if we could make sure that updated test still triggers the
original bug, there's no reason _notrun for 64k case.

Thanks,
Eryu