Re: [PATCH] qemu: tighten semantics of 'size' when resizing block devices

When VIR_DOMAIN_BLOCK_RESIZE_CAPACITY is set, the 'size' parameter is currently ignored. Since applications must none the less pass a value for this parameter, it is preferrable to declare some explicit semantics for it. This declare that the parameter must be 0, or the exact size of the underlying block device. The latter gives the management application the ability to sanity check that the block device size matches what they think it should be. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- src/libvirt-domain.c | 5 +++-- src/qemu/qemu_driver.c | 9 ++++++++- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c index 94e5672ed8..83abad251e 100644 --- a/src/libvirt-domain.c +++ b/src/libvirt-domain.c @@ -6389,8 +6389,9 @@ virDomainBlockPeek(virDomainPtr dom, * to the next alignment boundary. * * If @flag contains VIR_DOMAIN_BLOCK_RESIZE_CAPACITY (since 10.0.0) the - * hypervisor will resize the guest block device to fully fill the source, - * ignoring @size. This is possible only for image formats with no metadata + * hypervisor will resize the guest block device to fully fill the source. + * @size must be either set to zero, or to the exact size of the block + * device source. This is possible only for image formats with no metadata * ('raw') and for source devices with limited capacity such as block devices. * * The @disk parameter is either an unambiguous source name of the diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 49bc4a624d..8e529f97b5 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -9325,7 +9325,14 @@ qemuDomainBlockResize(virDomainPtr dom, goto endjob; } - size = disk->src->physical; + if (size == 0) { + size = disk->src->physical; + } else if (size != disk->src->physical) { + virReportError(VIR_ERR_INVALID_ARG, + _("block resize to full capacity %llu but validate size is %llu"),