On 05/13/2010 05:09 AM, Daniel P. Berrange wrote:
> The virDomainGetBlockInfo API allows query physical block
> extent and allocated block extent. These are normally the
> same value unless storing a special format like qcow2
> inside a block device. In this scenario we can query QEMU
> to get the actual allocated extent.
>
> + /* Set default value .. */
> info->allocation = info->physical;
>
> - ret = 0;
> + /* ..but if guest is running & not using raw
> + disk format and on a block device, then query
> + highest allocated extent from QEMU */
> + if (virDomainObjIsActive(vm) &&
> + meta.format != VIR_STORAGE_FILE_RAW &&
> + S_ISBLK(sb.st_mode)) {
> + qemuDomainObjPrivatePtr priv = vm->privateData;
> + if (qemuDomainObjBeginJob(vm) < 0)
> + goto cleanup;
> +
> + qemuDomainObjEnterMonitor(vm);
> + ret = qemuMonitorGetBlockExtent(priv->mon,
> + disk->info.alias,
> + &info->allocation);
This sets info->allocation to 0 if...
> +int qemuMonitorGetBlockExtent(qemuMonitorPtr mon,
> + const char *devname,
> + unsigned long long *extent)
> +{
> + int ret;
> + DEBUG("mon=%p, fd=%d, devname=%p",
> + mon, mon->fd, devname);
> +
> + if (mon->json)
> + ret = qemuMonitorJSONGetBlockExtent(mon, devname, extent);
> + else
> + ret = qemuMonitorTextGetBlockExtent(mon, devname, extent);
...we don't have JSON support...
> +int qemuMonitorTextGetBlockExtent(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
> + const char *devname ATTRIBUTE_UNUSED,
> + unsigned long long *extent)
> +{
> + /* Not supported in text monitor, but we don't want to
> + * cause an error in callers in this scenario, just
> + * fallback to marking the data unavailable */
> + *extent = 0;
> + return 0;
> +}
Wouldn't it be better to check if qemu sets things to 0 (because max
extent is not supported), and in that case, fall back to the original
default of info->physical?
--
Eric Blake eblake@xxxxxxxxxx +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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