From 5853ac5261b2934ca300b24a7bd78cc4b377c90c Mon Sep 17 00:00:00 2001
Message-Id: <5853ac5261b2934ca300b24a7bd78cc4b377c90c@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Thu, 7 Jul 2022 17:37:46 +0200
Subject: [PATCH] qemu: Make IOThread changing more robust
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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 <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
(cherry picked from commit 6db9c95a45d4e24cdcd5c009b7fe5da3745b5d59)
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2059511
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
src/qemu/qemu_driver.c | 74 ++++++++++++++++++++++++------------------
1 file changed, 43 insertions(+), 31 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 3b5c3db67c..2c627396f1 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5594,6 +5594,7 @@ qemuDomainChgIOThread(virQEMUDriver *driver,
{
g_autoptr(virQEMUDriverConfig) cfg = NULL;
qemuDomainObjPrivate *priv;
+ g_autoptr(virDomainDef) defcopy = NULL;
virDomainDef *def;
virDomainDef *persistentDef;
virDomainIOThreadIDDef *iothreaddef = NULL;
@@ -5609,34 +5610,34 @@ qemuDomainChgIOThread(virQEMUDriver *driver,
if (virDomainObjGetDefs(vm, flags, &def, &persistentDef) < 0)
goto endjob;
- if (def) {
- if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
- virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
- _("IOThreads not supported with this binary"));
- 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(def, iothread.iothread_id) < 0)
+ if (virDomainDriverAddIOThreadCheck(defcopy, iothread.iothread_id) < 0)
goto endjob;
- if (qemuDomainHotplugAddIOThread(driver, vm, iothread.iothread_id) < 0)
+ if (!virDomainIOThreadIDAdd(defcopy, iothread.iothread_id))
goto endjob;
break;
case VIR_DOMAIN_IOTHREAD_ACTION_DEL:
- if (virDomainDriverDelIOThreadCheck(def, iothread.iothread_id) < 0)
+ if (virDomainDriverDelIOThreadCheck(defcopy, iothread.iothread_id) < 0)
goto endjob;
- if (qemuDomainHotplugDelIOThread(driver, vm, iothread.iothread_id) < 0)
- goto endjob;
+ virDomainIOThreadIDDel(defcopy, iothread.iothread_id);
break;
case VIR_DOMAIN_IOTHREAD_ACTION_MOD:
- iothreaddef = virDomainIOThreadIDFind(def, iothread.iothread_id);
+ iothreaddef = virDomainIOThreadIDFind(defcopy, iothread.iothread_id);
if (!iothreaddef) {
virReportError(VIR_ERR_INVALID_ARG,
@@ -5645,41 +5646,47 @@ qemuDomainChgIOThread(virQEMUDriver *driver,
goto endjob;
}
- if (qemuDomainIOThreadValidate(iothreaddef, iothread, true) < 0)
+ if (qemuDomainIOThreadValidate(iothreaddef, iothread, false) < 0)
goto endjob;
- if (qemuDomainHotplugModIOThread(driver, vm, iothread) < 0)
+ if (qemuDomainHotplugModIOThreadIDDef(iothreaddef, iothread) < 0) {
+ virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+ _("configuring persistent polling values is not supported"));
goto endjob;
+ }
- qemuDomainHotplugModIOThreadIDDef(iothreaddef, iothread);
break;
-
}
-
- qemuDomainSaveStatus(vm);
}
- if (persistentDef) {
+ if (def) {
+ if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("IOThreads not supported with this binary"));
+ goto endjob;
+ }
+
switch (action) {
case VIR_DOMAIN_IOTHREAD_ACTION_ADD:
- if (virDomainDriverAddIOThreadCheck(persistentDef, iothread.iothread_id) < 0)
+ if (virDomainDriverAddIOThreadCheck(def, iothread.iothread_id) < 0)
goto endjob;
- if (!virDomainIOThreadIDAdd(persistentDef, iothread.iothread_id))
+ if (qemuDomainHotplugAddIOThread(driver, vm, iothread.iothread_id) < 0)
goto endjob;
break;
case VIR_DOMAIN_IOTHREAD_ACTION_DEL:
- if (virDomainDriverDelIOThreadCheck(persistentDef, iothread.iothread_id) < 0)
+ if (virDomainDriverDelIOThreadCheck(def, iothread.iothread_id) < 0)
goto endjob;
- virDomainIOThreadIDDel(persistentDef, iothread.iothread_id);
+ if (qemuDomainHotplugDelIOThread(driver, vm, iothread.iothread_id) < 0)
+ goto endjob;
break;
case VIR_DOMAIN_IOTHREAD_ACTION_MOD:
- iothreaddef = virDomainIOThreadIDFind(persistentDef, iothread.iothread_id);
+ iothreaddef = virDomainIOThreadIDFind(def, iothread.iothread_id);
if (!iothreaddef) {
virReportError(VIR_ERR_INVALID_ARG,
@@ -5688,21 +5695,26 @@ qemuDomainChgIOThread(virQEMUDriver *driver,
goto endjob;
}
- if (qemuDomainIOThreadValidate(iothreaddef, iothread, false) < 0)
+ if (qemuDomainIOThreadValidate(iothreaddef, iothread, true) < 0)
goto endjob;
- if (qemuDomainHotplugModIOThreadIDDef(iothreaddef, iothread) < 0) {
- virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
- _("configuring persistent polling values is not supported"));
+ if (qemuDomainHotplugModIOThread(driver, vm, iothread) < 0)
goto endjob;
- }
+ qemuDomainHotplugModIOThreadIDDef(iothreaddef, iothread);
break;
+
}
- if (virDomainDefSave(persistentDef, driver->xmlopt,
- cfg->configDir) < 0)
+ qemuDomainSaveStatus(vm);
+ }
+
+ /* 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