[libvirt] [PATCH 1/1] qemu: hide details of fake reboot

Nikolay Shirokovskiy nshirokovskiy at virtuozzo.com
Wed Oct 30 08:09:42 UTC 2019


If we use fake reboot then domain goes thru running->shutdown->running
state changes with shutdown state only for short period of time.  At
least this is implementation details leaking into API. And also there is
one real case when this is not convinient. I'm doing a backup with the
help of temporary block snapshot (with the help of qemu's API which is
used in the newly created libvirt's backup API). If guest is shutdowned
I want to continue to backup so I don't kill the process and domain is
in shutdown state. Later when backup is finished I want to destroy qemu
process. So I check if it is in shutdowned state and destroy it if it
is. Now if instead of shutdown domain got fake reboot then I can destroy
process in the middle of fake reboot process.

After shutdown event we also get stop event and now as domain state is
running it will be transitioned to paused state and back to running
later. Though this is not critical for the described case I guess it is
better not to leak these details to user too. So let's leave domain in
running state on stop event if fake reboot is in process.

As we don't know when stop event really arrive let's move resetting flag
after starting CPUs - at this point stop event should be handled.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
---
 src/qemu/qemu_process.c | 57 ++++++++++++++++++++++-------------------
 1 file changed, 31 insertions(+), 26 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index ed8666e9d1..2d37f92724 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -500,6 +500,8 @@ qemuProcessFakeReboot(void *opaque)
         goto endjob;
     }
 
+    qemuDomainSetFakeReboot(driver, vm, false);
+
     if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm, driver->caps) < 0) {
         VIR_WARN("Unable to save status on vm %s after state change",
                  vm->def->name);
@@ -525,7 +527,6 @@ qemuProcessShutdownOrReboot(virQEMUDriverPtr driver,
     qemuDomainObjPrivatePtr priv = vm->privateData;
 
     if (priv->fakeReboot) {
-        qemuDomainSetFakeReboot(driver, vm, false);
         virObjectRef(vm);
         virThread th;
         if (virThreadCreate(&th,
@@ -534,6 +535,7 @@ qemuProcessShutdownOrReboot(virQEMUDriverPtr driver,
                             vm) < 0) {
             VIR_ERROR(_("Failed to create reboot thread, killing domain"));
             ignore_value(qemuProcessKill(vm, VIR_QEMU_PROCESS_KILL_NOWAIT));
+            qemuDomainSetFakeReboot(driver, vm, false);
             virObjectUnref(vm);
         }
     } else {
@@ -595,35 +597,37 @@ qemuProcessHandleShutdown(qemuMonitorPtr mon G_GNUC_UNUSED,
         goto unlock;
     }
 
-    VIR_DEBUG("Transitioned guest %s to shutdown state",
-              vm->def->name);
-    virDomainObjSetState(vm,
-                         VIR_DOMAIN_SHUTDOWN,
-                         VIR_DOMAIN_SHUTDOWN_UNKNOWN);
+    if (!priv->fakeReboot) {
+        VIR_DEBUG("Transitioned guest %s to shutdown state",
+                  vm->def->name);
+        virDomainObjSetState(vm,
+                             VIR_DOMAIN_SHUTDOWN,
+                             VIR_DOMAIN_SHUTDOWN_UNKNOWN);
 
-    switch (guest_initiated) {
-    case VIR_TRISTATE_BOOL_YES:
-        detail = VIR_DOMAIN_EVENT_SHUTDOWN_GUEST;
-        break;
+        switch (guest_initiated) {
+        case VIR_TRISTATE_BOOL_YES:
+            detail = VIR_DOMAIN_EVENT_SHUTDOWN_GUEST;
+            break;
 
-    case VIR_TRISTATE_BOOL_NO:
-        detail = VIR_DOMAIN_EVENT_SHUTDOWN_HOST;
-        break;
+        case VIR_TRISTATE_BOOL_NO:
+            detail = VIR_DOMAIN_EVENT_SHUTDOWN_HOST;
+            break;
 
-    case VIR_TRISTATE_BOOL_ABSENT:
-    case VIR_TRISTATE_BOOL_LAST:
-    default:
-        detail = VIR_DOMAIN_EVENT_SHUTDOWN_FINISHED;
-        break;
-    }
+        case VIR_TRISTATE_BOOL_ABSENT:
+        case VIR_TRISTATE_BOOL_LAST:
+        default:
+            detail = VIR_DOMAIN_EVENT_SHUTDOWN_FINISHED;
+            break;
+        }
 
-    event = virDomainEventLifecycleNewFromObj(vm,
-                                              VIR_DOMAIN_EVENT_SHUTDOWN,
-                                              detail);
+        event = virDomainEventLifecycleNewFromObj(vm,
+                                                  VIR_DOMAIN_EVENT_SHUTDOWN,
+                                                  detail);
 
-    if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm, driver->caps) < 0) {
-        VIR_WARN("Unable to save status on vm %s after state change",
-                 vm->def->name);
+        if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm, driver->caps) < 0) {
+            VIR_WARN("Unable to save status on vm %s after state change",
+                     vm->def->name);
+        }
     }
 
     if (priv->agent)
@@ -657,7 +661,8 @@ qemuProcessHandleStop(qemuMonitorPtr mon G_GNUC_UNUSED,
     reason = priv->pausedReason;
     priv->pausedReason = VIR_DOMAIN_PAUSED_UNKNOWN;
 
-    if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING) {
+    if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING &&
+        !priv->fakeReboot) {
         if (priv->job.asyncJob == QEMU_ASYNC_JOB_MIGRATION_OUT) {
             if (priv->job.current->status == QEMU_DOMAIN_JOB_STATUS_POSTCOPY)
                 reason = VIR_DOMAIN_PAUSED_POSTCOPY;
-- 
2.23.0




More information about the libvir-list mailing list