Re: [Qemu-devel] [PATCH v5 0/2] qemu-img: Check for backing image if specified during create

[Kevin Wolf <kwolf@redhat.com>]

Am 18.07.2017 um 02:34 hat John Snow geschrieben:
> We do not currently guarantee that QEMU will or will not open a
> backing file when creating a new overlay file. Presently, QEMU will
> not open that file if you provide a filesize, because it has no reason
> to want to open it in that case.
> 
> This series makes the contract more explicit: if '-u' is provided to
> create, we will not open the backing image regardless, erroring out if
> a size was not provided.
> 
> In the other case, if '-u' is not provided, we now endeavor to open the
> backing image if possible to check that it exists. For now, if a size
> is provided and the image does not exist, QEMU will only warn to maintain
> compatibility with legacy behavior.
> 
> In the future, QEMU may treat the operation as a failure if '-u' was not
> provided.
> 
> Tests are amended primarily to pass the '-u' flag where it makes sense;
> which is when creating overlays for objects already open by QEMU. These
> will now generally fail to succeed because of image locking. In this
> case, they only warn instead of fail, but this keeps the output cleaner.
> 
> Test 111 is updated to accommodate a new error message.
> 082, 085, 139, 156 and 158 add '-u' just to suppress warnings.

Thanks, applied to the block branch.

Kevin