There are three APIs that allow changing IOThreads:
virDomainAddIOThread()
virDomainDelIOThread()
virDomainSetIOThreadParams()
In case of QEMU driver these are handled by
qemuDomainChgIOThread() which attempts to be versatile enough to
work on both inactive and live domain definitions at the same
time. However, it's a bit clumsy - when a change to live
definition succeeds but fails in inactive definition then there's
no rollback. And somewhat rightfully so - changes to live
definition are in general harder to roll back. Therefore, do what
we do elsewhere (qemuDomainAttachDeviceLiveAndConfig(),
qemuDomainDetachDeviceAliasLiveAndConfig(), ...):
1) do the change to inactive XML first,
2) in fact, do the change to a copy of inactive XML,
3) swap inactive XML and its copy only after everything
succeeded.
Signed-off-by: Michal Privoznik <mpriv...@redhat.com>
---
src/qemu/qemu_driver.c | 98 ++++++++++++++++++++++++------------------
1 file changed, 55 insertions(+), 43 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c4418df1ed..e30b1b8d84 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5595,6 +5595,7 @@ qemuDomainChgIOThread(virQEMUDriver *driver,
{
g_autoptr(virQEMUDriverConfig) cfg = NULL;
qemuDomainObjPrivate *priv;
+ g_autoptr(virDomainDef) defcopy = NULL;
virDomainDef *def;
virDomainDef *persistentDef;
virDomainIOThreadIDDef *iothreaddef = NULL;
@@ -5610,6 +5611,55 @@ qemuDomainChgIOThread(virQEMUDriver *driver,
if (virDomainObjGetDefs(vm, flags, &def, &persistentDef) < 0)
goto endjob;
+ if (persistentDef) {
+ /* Make a copy of persistent definition and do all the changes there.
+ * Swap the definitions only after changes to live definition
+ * succeeded. */
+ if (!(defcopy = virDomainObjCopyPersistentDef(vm, driver->xmlopt,
+ priv->qemuCaps)))
+ return -1;
+
+ switch (action) {
+ case VIR_DOMAIN_IOTHREAD_ACTION_ADD:
+ if (virDomainDriverAddIOThreadCheck(defcopy, iothread.iothread_id)
< 0)
+ goto endjob;
+
+ if (!virDomainIOThreadIDAdd(defcopy, iothread.iothread_id))
+ goto endjob;
+
+ break;
+
+ case VIR_DOMAIN_IOTHREAD_ACTION_DEL:
+ if (virDomainDriverDelIOThreadCheck(defcopy, iothread.iothread_id)
< 0)
+ goto endjob;
+
+ virDomainIOThreadIDDel(defcopy, iothread.iothread_id);
+
+ break;
+
+ case VIR_DOMAIN_IOTHREAD_ACTION_MOD:
+ iothreaddef = virDomainIOThreadIDFind(defcopy,
iothread.iothread_id);
+
+ if (!iothreaddef) {
+ virReportError(VIR_ERR_INVALID_ARG,
+ _("cannot find IOThread '%u' in iothreadids"),
+ iothread.iothread_id);
+ goto endjob;
+ }
+
+ if (qemuDomainIOThreadValidate(iothreaddef, iothread, false) < 0)
+ goto endjob;
+
+ if (qemuDomainHotplugModIOThreadIDDef(iothreaddef, iothread) < 0) {
+ virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+ _("configuring persistent polling values is not
supported"));
+ goto endjob;
+ }
+
+ break;
+ }
+ }
+
if (def) {
if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
@@ -5660,50 +5710,12 @@ qemuDomainChgIOThread(virQEMUDriver *driver,
qemuDomainSaveStatus(vm);
}
- if (persistentDef) {
- switch (action) {
- case VIR_DOMAIN_IOTHREAD_ACTION_ADD:
- if (virDomainDriverAddIOThreadCheck(persistentDef,
iothread.iothread_id) < 0)
- goto endjob;
-
- if (!virDomainIOThreadIDAdd(persistentDef, iothread.iothread_id))
- goto endjob;
-
- break;
-
- case VIR_DOMAIN_IOTHREAD_ACTION_DEL:
- if (virDomainDriverDelIOThreadCheck(persistentDef,
iothread.iothread_id) < 0)
- goto endjob;
-
- virDomainIOThreadIDDel(persistentDef, iothread.iothread_id);
-
- break;
-
- case VIR_DOMAIN_IOTHREAD_ACTION_MOD:
- iothreaddef = virDomainIOThreadIDFind(persistentDef,
iothread.iothread_id);
-
- if (!iothreaddef) {
- virReportError(VIR_ERR_INVALID_ARG,
- _("cannot find IOThread '%u' in iothreadids"),
- iothread.iothread_id);
- goto endjob;
- }
-
- if (qemuDomainIOThreadValidate(iothreaddef, iothread, false) < 0)
- goto endjob;
-
- if (qemuDomainHotplugModIOThreadIDDef(iothreaddef, iothread) < 0) {
- virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
- _("configuring persistent polling values is not
supported"));
- goto endjob;
- }
-
- break;
- }
-
- if (virDomainDefSave(persistentDef, driver->xmlopt,
- cfg->configDir) < 0)
+ /* Finally, if no error until here, we can save config. */
+ if (defcopy) {
+ if (virDomainDefSave(defcopy, driver->xmlopt, cfg->configDir) < 0)
goto endjob;
+
+ virDomainObjAssignDef(vm, &defcopy, false, NULL);
}
ret = 0;
--
2.35.1
