[PATCH v2 1/3] iotests: Specify explicit backing format where sensible

[Eric Blake]

On 2/27/20 7:08 AM, Eric Blake wrote:

>>> The change in libvirt to reject images without explicit backing format
>>> has pointed out that a number of tools have been far too reliant on
>>> probing in the past.  It's time to set a better example in our own
>>> iotests of properly setting this parameter.
>>>
>>> iotest calls to create, rebase, convert, and amend are all impacted to
>>> some degree.  It's a bit annoying that we are inconsistent on command
>>> line - while all of those accept -o backing_file=...,backing_fmt=...,
>>> the shortcuts are different: create and rebase have -b and -F, convert
>>> has -B but no -F, and amend has no shortcuts.
>>>
>>> Signed-off-by: Eric Blake <eblake at redhat.com>
>>> ---
>>
>> [...]
>>
>> Test #225 still uses -b without a format:
>>
>> ./check -vmdk 225
> 
> Oh, good catch (I only ran ./check -qcow2, -nbd, and -raw).

Urgh - running './check -vmdk' shows failures in:

017 018 019 020 034 037 069 110 126 216 225 279

all similar to:

-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576 
backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
+qemu-img: TEST_DIR/t.IMGFMT: Backing file format not supported for file 
format 'IMGFMT'

with knock-on effects.  I guess I first have to fix outlier formats like 
vmdk to ignore a backing file format where it does not hurt.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org