Re: [PATCH 2/2] iotests: Add loop-accept-ro-dev test

[Eric Blake <eblake@redhat.com>]

On Wed, Oct 28, 2026 at 06:10:57PM +0100, Kevin Wolf wrote:
> Add a test for the accept-read-only-device option of host_device.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  tests/qemu-iotests/tests/loop-accept-ro-dev   | 87 +++++++++++++++++++
>  .../qemu-iotests/tests/loop-accept-ro-dev.out | 19 ++++
>  2 files changed, 106 insertions(+)
>  create mode 100755 tests/qemu-iotests/tests/loop-accept-ro-dev
>  create mode 100644 tests/qemu-iotests/tests/loop-accept-ro-dev.out
> 

> +
> +run_qemu()
> +{
> +    echo -e '{"execute":"qmp_capabilities"}\n{"execute":"quit"}' |

'printf %s' is slightly more portable than 'echo -e'; even though this
script uses /bin/bash, you can use 'shopt -s xpg_echo' to break the
latter. On the other hand, this is copy-paste from other tests, so not
a showstopper.

> +    do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qemu | _filter_qmp |
> +        _filter_generated_node_ids | _filter_imgfmt |
> +        _filter_actual_image_size | _filter_img_info
> +}
> +
> +if ! sudo -n losetup &>/dev/null; then
> +    _notrun "sudo losetup not available"
> +fi

Huh - we seem to have several outstanding patches related to probing
whether losetup is usable:

https://lists.nongnu.org/archive/html/qemu-devel/2026-10/msg02963.html
https://lists.nongnu.org/archive/html/qemu-devel/2026-10/msg01918.html

Is this a common enough pattern in our qemu-iotests that we should
factor it out?

> +++ b/tests/qemu-iotests/tests/loop-accept-ro-dev.out
> @@ -0,0 +1,19 @@
> +QA output created by loop-accept-ro-dev
> +
> +=== Start QEMU on a loop device after blockdev --setro ===
> +
> +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
> +Testing: -blockdev host_device,node-name=disk,filename=/dev/loop1 -device virtio-blk,drive=disk
> +QEMU_PROG: -blockdev host_device,node-name=disk,filename=/dev/loop1: The device is not writable: Permission denied
> +
> +Testing: -blockdev host_device,node-name=disk,filename=/dev/loop1,accept-read-only-device=off -device virtio-blk,drive=disk

/dev/loop1 might already be busy, at which point losetup will pick
/dev/loop2 or similar. This output needs to be filtered.

The rest of the test looks okay.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization:  qemu.org | libguestfs.org