[libvirt] [PATCH] qemu: Allow migration to be cancelled at any phase

[Michal Privoznik]

Currently, if user calls virDomainAbortJob we just issue
'migrate_cancel' and hope for the best. However, if user calls
the API in wrong phase when migration hasn't been started yet
(perform phase) the cancel request is just ignored. With this
patch, the request is remembered and as soon as perform phase
starts, migration is cancelled.
---
 src/qemu/qemu_domain.c    |   26 ++++++++++++++++++++++++++
 src/qemu/qemu_domain.h    |    4 ++++
 src/qemu/qemu_driver.c    |   31 +++++++++++++++++++++++++++----
 src/qemu/qemu_migration.c |   43 +++++++++++++++++++++++++++++++++++++++++--
 4 files changed, 98 insertions(+), 6 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index a5592b9..031be5f 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -160,6 +160,7 @@ qemuDomainObjResetAsyncJob(qemuDomainObjPrivatePtr priv)
     job->mask = DEFAULT_JOB_MASK;
     job->start = 0;
     job->dump_memory_only = false;
+    job->asyncAbort = false;
     memset(&job->info, 0, sizeof(job->info));
 }
 
@@ -959,6 +960,31 @@ qemuDomainObjEndAsyncJob(struct qemud_driver *driver, virDomainObjPtr obj)
     return virObjectUnref(obj);
 }
 
+void
+qemuDomainObjAbortAsyncJob(virDomainObjPtr obj)
+{
+    qemuDomainObjPrivatePtr priv = obj->privateData;
+
+    VIR_DEBUG("Requesting abort of async job: %s",
+              qemuDomainAsyncJobTypeToString(priv->job.asyncJob));
+
+    priv->job.asyncAbort = true;
+}
+
+/**
+ * qemuDomainObjAbortAsyncJobRequested:
+ * @obj: domain object
+ *
+ * Was abort requested? @obj MUST be locked when calling this.
+ */
+bool
+qemuDomainObjAbortAsyncJobRequested(virDomainObjPtr obj)
+{
+    qemuDomainObjPrivatePtr priv = obj->privateData;
+
+    return priv->job.asyncAbort;
+}
+
 static int
 qemuDomainObjEnterMonitorInternal(struct qemud_driver *driver,
                                   bool driver_locked,
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 9c2f67c..9a31bbe 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -111,6 +111,7 @@ struct qemuDomainJobObj {
     unsigned long long start;           /* When the async job started */
     bool dump_memory_only;              /* use dump-guest-memory to do dump */
     virDomainJobInfo info;              /* Async job progress data */
+    bool asyncAbort;                    /* abort of async job requested */
 };
 
 typedef struct _qemuDomainPCIAddressSet qemuDomainPCIAddressSet;
@@ -204,6 +205,9 @@ bool qemuDomainObjEndJob(struct qemud_driver *driver,
 bool qemuDomainObjEndAsyncJob(struct qemud_driver *driver,
                               virDomainObjPtr obj)
     ATTRIBUTE_RETURN_CHECK;
+void qemuDomainObjAbortAsyncJob(virDomainObjPtr obj);
+bool qemuDomainObjAbortAsyncJobRequested(virDomainObjPtr obj);
+
 void qemuDomainObjSetJobPhase(struct qemud_driver *driver,
                               virDomainObjPtr obj,
                               int phase);
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 7b8eec6..009c2c8 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -10331,6 +10331,8 @@ static int qemuDomainAbortJob(virDomainPtr dom) {
     virDomainObjPtr vm;
     int ret = -1;
     qemuDomainObjPrivatePtr priv;
+    /* Poll every 50ms for job termination */
+    struct timespec ts = { .tv_sec = 0, .tv_nsec = 50 * 1000 * 1000ull };
 
     qemuDriverLock(driver);
     vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@@ -10365,10 +10367,31 @@ static int qemuDomainAbortJob(virDomainPtr dom) {
         goto endjob;
     }
 
-    VIR_DEBUG("Cancelling job at client request");
-    qemuDomainObjEnterMonitor(driver, vm);
-    ret = qemuMonitorMigrateCancel(priv->mon);
-    qemuDomainObjExitMonitor(driver, vm);
+    qemuDomainObjAbortAsyncJob(vm);
+    VIR_DEBUG("Waiting for async job '%s' to finish",
+              qemuDomainAsyncJobTypeToString(priv->job.asyncJob));
+    while (priv->job.asyncJob) {
+        if (qemuDomainObjEndJob(driver, vm) == 0) {
+            vm = NULL;
+            goto cleanup;
+        }
+        virDomainObjUnlock(vm);
+
+        nanosleep(&ts, NULL);
+
+        virDomainObjLock(vm);
+        if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_ABORT) < 0)
+            goto cleanup;
+
+        if (!virDomainObjIsActive(vm)) {
+            virReportError(VIR_ERR_OPERATION_INVALID,
+                           "%s", _("domain is not running"));
+            goto endjob;
+        }
+
+    }
+
+    ret = 0;
 
 endjob:
     if (qemuDomainObjEndJob(driver, vm) == 0)
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 5f8a9c5..c840686 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1172,6 +1172,12 @@ qemuMigrationUpdateJobStatus(struct qemud_driver *driver,
     }
     priv->job.info.timeElapsed -= priv->job.start;
 
+    if (qemuDomainObjAbortAsyncJobRequested(vm)) {
+        VIR_DEBUG("Migration abort requested. Translating "
+                  "status to MIGRATION_STATUS_CANCELLED");
+        status = QEMU_MONITOR_MIGRATION_STATUS_CANCELLED;
+    }
+
     ret = -1;
     switch (status) {
     case QEMU_MONITOR_MIGRATION_STATUS_INACTIVE:
@@ -1214,6 +1220,35 @@ qemuMigrationUpdateJobStatus(struct qemud_driver *driver,
     return ret;
 }
 
+static int
+qemuMigrationCancel(struct qemud_driver *driver, virDomainObjPtr vm)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    int ret = -1;
+
+    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_ABORT) < 0)
+        goto cleanup;
+
+    if (!virDomainObjIsActive(vm)) {
+        virReportError(VIR_ERR_OPERATION_INVALID,
+                       "%s", _("domain is not running"));
+        goto endjob;
+    }
+
+    qemuDomainObjEnterMonitor(driver, vm);
+    ret = qemuMonitorMigrateCancel(priv->mon);
+    qemuDomainObjExitMonitor(driver, vm);
+
+endjob:
+    if (qemuDomainObjEndJob(driver, vm) == 0) {
+        virReportError(VIR_ERR_OPEN_FAILED, "%s",
+                       _("domain unexpectedly died"));
+        ret = -1;
+    }
+
+cleanup:
+    return ret;
+}
 
 static int
 qemuMigrationWaitForCompletion(struct qemud_driver *driver, virDomainObjPtr vm,
@@ -1262,10 +1297,14 @@ qemuMigrationWaitForCompletion(struct qemud_driver *driver, virDomainObjPtr vm,
     }
 
 cleanup:
-    if (priv->job.info.type == VIR_DOMAIN_JOB_COMPLETED)
+    if (priv->job.info.type == VIR_DOMAIN_JOB_COMPLETED) {
         return 0;
-    else
+    } else {
+        if (priv->job.info.type == VIR_DOMAIN_JOB_CANCELLED &&
+            qemuMigrationCancel(driver, vm) < 0)
+            VIR_DEBUG("Cancelling job at client request");
         return -1;
+    }
 }
 
 
-- 
1.7.8.6