[libvirt] [PATCH 2/1] qemu: reject blockiotune if qemu too old

[Eric Blake]

Commit 4c82f09e added a capability check for qemu per-device io
throttling, but only applied it to domain startup.  As mentioned
in the previous commit, we stil end up with an internal error
if the monitor command doesn't also exist, not to mention the
confusion of allowing tuning on inactive domains only to then
be rejected when starting the domain.

* src/qemu/qemu_driver.c (qemuDomainSetBlockIoTune): Reject
offline tuning if online can't match it.
---
 src/qemu/qemu_driver.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 2fde15b..c100a1a 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -11936,6 +11936,13 @@ qemuDomainSetBlockIoTune(virDomainPtr dom,
                         _("no domain with matching uuid '%s'"), uuidstr);
         goto cleanup;
     }
+    priv = vm->privateData;
+    if (!qemuCapsGet(priv->qemuCaps, QEMU_CAPS_DRIVE_IOTUNE)) {
+        qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                        _("block I/O throttling not supported with this "
+                          "QEMU binary"));
+        goto cleanup;
+    }

     device = qemuDiskPathToAlias(vm, disk, &idx);
     if (!device) {
@@ -12007,7 +12014,6 @@ qemuDomainSetBlockIoTune(virDomainPtr dom,
             info.read_iops_sec = oldinfo->read_iops_sec;
             info.write_iops_sec = oldinfo->write_iops_sec;
         }
-        priv = vm->privateData;
         qemuDomainObjEnterMonitorWithDriver(driver, vm);
         ret = qemuMonitorSetBlockIoThrottle(priv->mon, device, &info);
         qemuDomainObjExitMonitorWithDriver(driver, vm);
-- 
1.7.7.6