Re: [PATCH v2 1/4] iotests/109: Don't mirror with mismatched size

[Kevin Wolf <kwolf@redhat.com>]

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Am 11.05.2020 um 17:08 hat Max Reitz geschrieben:
> On 11.05.20 15:58, Kevin Wolf wrote:
> > This patch makes the raw image the same size as the file in a different
> > format that is mirrored as raw to it to avoid errors when mirror starts
> > to enforce that source and target are the same size.
> > 
> > We check only that the first 512 bytes are zeroed (instead of 64k)
> > because some image formats create image files that are smaller than 64k,
> > so trying to read 64k would result in I/O errors. Apart from this, 512
> > is more appropriate anyway because the raw format driver protects
> > specifically the first 512 bytes.
> > 
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> >  tests/qemu-iotests/109           | 10 ++---
> >  tests/qemu-iotests/109.out       | 74 +++++++++++++-------------------
> >  tests/qemu-iotests/common.filter |  5 +++
> >  3 files changed, 41 insertions(+), 48 deletions(-)
> > 
> > diff --git a/tests/qemu-iotests/109 b/tests/qemu-iotests/109
> > index 5bc2e9b001..3ffeaf3c55 100755
> > --- a/tests/qemu-iotests/109
> > +++ b/tests/qemu-iotests/109
> > @@ -77,14 +77,14 @@ for fmt in qcow qcow2 qed vdi vmdk vpc; do
> >      echo "=== Writing a $fmt header into raw ==="
> >      echo
> >  
> > -    _make_test_img 64M
> >      TEST_IMG="$TEST_IMG.src" IMGFMT=$fmt _make_test_img 64M
> > +    _make_test_img $(du -b "$TEST_IMG.src" | cut -f1) | _filter_img_create_size
> 
> Why du and not the file length (stat -c '%s')?

Because the test from which I copied had 'du' and the internet claimed
that 'stat -c' isn't portable. Now I see that we do use it in other test
cases, so I guess it would have been fine, too. Is there a good reason
why 'stat' would be better?

Kevin

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