Re: [PATCH for-5.1 2/2] iotests: Test sparseness for qemu-img convert -n

[Nir Soffer <nsoffer@redhat.com>]

On Mon, Jul 20, 2020 at 4:18 PM Kevin Wolf <kwolf@redhat.com> wrote:
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  tests/qemu-iotests/122     | 34 ++++++++++++++++++++++++++++++++++
>  tests/qemu-iotests/122.out | 17 +++++++++++++++++
>  2 files changed, 51 insertions(+)
>
> diff --git a/tests/qemu-iotests/122 b/tests/qemu-iotests/122
> index dfd1cd05d6..1112fc0730 100755
> --- a/tests/qemu-iotests/122
> +++ b/tests/qemu-iotests/122
> @@ -281,6 +281,40 @@ $QEMU_IMG convert -O $IMGFMT -n "$TEST_IMG" "$TEST_IMG".orig
>
>  $QEMU_IMG compare "$TEST_IMG" "$TEST_IMG".orig
>
> +echo
> +echo '=== -n to an empty image ==='
> +echo
> +
> +_make_test_img 64M

Why make a test image here? We create it again below twice

> +
> +# Convert with -n, which should not result in a fully allocated image, not even
> +# with compat=0.10 (because the target doesn't have a backing file)
> +TEST_IMG="$TEST_IMG".orig _make_test_img -o compat=1.1 64M
> +$QEMU_IMG convert -O $IMGFMT -n "$TEST_IMG" "$TEST_IMG".orig
> +$QEMU_IMG map --output=json "$TEST_IMG".orig

This looks reversed - "$TEST_IMG".orig is the original image, and "$TEST_IMG"
is the target image. So maybe use "$TEST_IMG".target?

> +
> +TEST_IMG="$TEST_IMG".orig _make_test_img -o compat=0.10 64M
> +$QEMU_IMG convert -O $IMGFMT -n "$TEST_IMG" "$TEST_IMG".orig
> +$QEMU_IMG map --output=json "$TEST_IMG".orig

Since the only difference is the compat, why not use a loop?

for compat in 0.10 1.1; do
...

> +
> +echo
> +echo '=== -n to an empty image with a backing file ==='
> +echo
> +
> +_make_test_img 64M
> +TEST_IMG="$TEST_IMG".base _make_test_img 64M
> +
> +# Convert with -n, which should still not result in a fully allocated image for
> +# compat=1.1 (because it can use zero clusters), but it should be fully
> +# allocated with compat=0.10
> +TEST_IMG="$TEST_IMG".orig _make_test_img -b "$TEST_IMG".base -F $IMGFMT -o compat=1.1 64M
> +$QEMU_IMG convert -O $IMGFMT -n "$TEST_IMG" "$TEST_IMG".orig
> +$QEMU_IMG map --output=json "$TEST_IMG".orig

Do we have a real use case for this convert? Doesn't this hide all the
data in the
backing file by data from source?

Assuming source is:

src-top: A0--
dst-bas: --B0

And destination is:

dst-top: ----
dst-bas: CCCC

After the convert we will have:

dst-top: A0B0
dst-bas: CCCC

So entire backing of dst is hidden.

Nir

> +TEST_IMG="$TEST_IMG".orig _make_test_img -b "$TEST_IMG".base -F $IMGFMT -o compat=0.10 64M
> +$QEMU_IMG convert -O $IMGFMT -n "$TEST_IMG" "$TEST_IMG".orig
> +$QEMU_IMG map --output=json "$TEST_IMG".orig
> +
>  echo
>  echo '=== -n -B to an image without a backing file ==='
>  echo
> diff --git a/tests/qemu-iotests/122.out b/tests/qemu-iotests/122.out
> index f1f195ed77..b8028efb1d 100644
> --- a/tests/qemu-iotests/122.out
> +++ b/tests/qemu-iotests/122.out
> @@ -229,6 +229,23 @@ wrote 65536/65536 bytes at offset 0
>  64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>  Images are identical.
>
> +=== -n to an empty image ===
> +
> +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
> +Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=67108864
> +[{ "start": 0, "length": 67108864, "depth": 0, "zero": true, "data": false}]
> +Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=67108864
> +[{ "start": 0, "length": 67108864, "depth": 0, "zero": true, "data": false}]
> +
> +=== -n to an empty image with a backing file ===
> +
> +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
> +Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
> +Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
> +[{ "start": 0, "length": 67108864, "depth": 0, "zero": true, "data": false}]
> +Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
> +[{ "start": 0, "length": 67108864, "depth": 0, "zero": false, "data": true, "offset": 327680}]
> +
>  === -n -B to an image without a backing file ===
>
>  Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
> --
> 2.25.4
>