Re: [PATCH 1/2] qcow2: Make preallocate_co() resize the image to the correct size

[Max Reitz]

On 11.09.20 16:09, Alberto Garcia wrote:
> This function preallocates metadata structures and then extends the
> image to its new size, but that new size calculation is wrong because
> it doesn't take into account that the host_offset variable is always
> cluster-aligned.
> 
> This problem can be reproduced with preallocation=metadata when the
> original size is not cluster-aligned but the new size is. In this case
> the final image size will be shorter than expected.
> 
>    qemu-img create -f qcow2 img.qcow2 31k
>    qemu-img resize --preallocation=metadata img.qcow2 128k
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>  block/qcow2.c              |  1 +
>  tests/qemu-iotests/125     | 40 +++++++++++++++++++++-----------------
>  tests/qemu-iotests/125.out | 28 ++++++++++++++++++++++++--
>  3 files changed, 49 insertions(+), 20 deletions(-)

The test additions make this test fail with compat=0.10.  Are you OK
with disabling compat=0.10 by squashing this in?

diff --git a/tests/qemu-iotests/125 b/tests/qemu-iotests/125
index 1f35598b2b..894d53f2bd 100755
--- a/tests/qemu-iotests/125
+++ b/tests/qemu-iotests/125
@@ -43,6 +43,10 @@ get_image_size_on_host()

 _supported_fmt qcow2
 _supported_proto file
+# Growing a file with a backing file (without preallocation=full or
+# =falloc) requires zeroing the newly added area, which is impossible
+# to do quickly for v2 images, and hence is unsupported.
+_unsupported_imgopts 'compat=0.10'

 if [ -z "$TEST_IMG_FILE" ]; then
     TEST_IMG_FILE=$TEST_IMG

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