Re: [PATCH 04/15] iotests/040: Don't check image pattern on zero-length image

[Hanna Reitz]

On 22.03.22 17:19, John Snow wrote:
> On Tue, Mar 22, 2022, 10:22 AM Hanna Reitz <hreitz@redhat.com> wrote:
>
>     On 18.03.22 21:36, John Snow wrote:
>     > qemu-io fails on read/write with zero-length raw images, so skip
>     these
>     > when running the zero-length image tests.
>     >
>     > Signed-off-by: John Snow <jsnow@redhat.com>
>     > ---
>     >   tests/qemu-iotests/040 | 14 ++++++++++++--
>     >   1 file changed, 12 insertions(+), 2 deletions(-)
>
>     Doesn’t look specific to zero-length images, but the fact that we
>     do I/O
>     beyond the image size, i.e. any image below 1 MB would be affected.
>
>     Anyway, the zero-length image is the only one tested with a size
>     of less
>     than 1 MB, so this works.
>
>     Reviewed-by: Hanna Reitz <hreitz@redhat.com>
>
>
> (Check the cover letter, too - this patch is still good, but iotest 
> 040 still fails and I'm not 100% clear as to why.)

Sure, but I didn’t see anything wrong with the patch, so...

From a glance, I believe the problem to be that the commit job changed 
one image’s backing file string to contain a JSON description of a block 
graph including a throttle node.  The accompanying throttle group of 
course doesn’t exist outside of qemu, so qemu-io complains.

We never noticed because we just checked for “pattern verification 
failed”, which isn’t in the error message, so this was a pass.  I’ll 
take a closer look.

Hanna