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@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org