[libvirt] [PATCH RFC 50/51] qemu: blockjob: Add modern block job event handler

[Peter Krempa]

Add the infrastructure to handle block job events in the -blockdev era.

Some complexity is required as qemu does not bother to notify whether
the job was concluded successfully or failed. Thus it's necessary to
re-query the monitor.

To minimize the possibility of stuck jobs save the state into the XML
prior to handling everything so that the reconnect code can potentially
continue with the cleanup.

Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
 src/qemu/qemu_blockjob.c | 123 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 122 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_blockjob.c b/src/qemu/qemu_blockjob.c
index 020e7b3994..6aa8b1df51 100644
--- a/src/qemu/qemu_blockjob.c
+++ b/src/qemu/qemu_blockjob.c
@@ -390,6 +390,124 @@ qemuBlockJobEventProcessLegacy(virQEMUDriverPtr driver,
 }


+static int
+qemuBlockJobEventProcessConcluded(qemuBlockJobDataPtr job,
+                                  virQEMUDriverPtr driver,
+                                  virDomainObjPtr vm,
+                                  qemuDomainAsyncJob asyncJob,
+                                  virQEMUDriverConfigPtr cfg)
+{
+    qemuMonitorJobInfoPtr *jobinfo = NULL;
+    size_t njobinfo = 0;
+    size_t i;
+    int ret = -1;
+    int rc = 0;
+    bool refreshstate = job->state == QEMU_BLOCKJOB_STATE_CONCLUDED;
+
+    if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
+        goto cleanup;
+
+    /* fetch job state */
+    if (refreshstate)
+        rc = qemuMonitorGetJobInfo(qemuDomainGetMonitor(vm), &jobinfo, &njobinfo);
+    /* dismiss job in qemu */
+    if (rc >= 0)
+        rc = qemuMonitorJobDismiss(qemuDomainGetMonitor(vm), job->name);
+
+    if (qemuDomainObjExitMonitor(driver, vm) < 0 || rc < 0)
+        goto cleanup;
+
+    /* we need to fetch the error state as the event does not propagate it */
+    if (refreshstate) {
+        for (i = 0; i < njobinfo; i++) {
+            if (STRNEQ_NULLABLE(job->name, jobinfo[i]->id))
+                continue;
+
+            if (VIR_STRDUP(job->errmsg, jobinfo[i]->error) < 0)
+                goto cleanup;
+        }
+
+        if (i == njobinfo) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, _("failed to refresh job '%s'"),
+                           job->name);
+            goto cleanup;
+        }
+
+        if (job->errmsg)
+            job->state = QEMU_BLOCKJOB_STATE_FAILED;
+        else
+            job->state = QEMU_BLOCKJOB_STATE_COMPLETED;
+
+        /* write status XML */
+        if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm, driver->caps) < 0)
+            VIR_WARN("Unable to save status on vm %s after block job", vm->def->name);
+    }
+
+    /* TODO: implement handlers for job types */
+    switch (job->type) {
+    case QEMU_BLOCKJOB_TYPE_PULL:
+    case QEMU_BLOCKJOB_TYPE_COPY:
+    case QEMU_BLOCKJOB_TYPE_COMMIT:
+    case QEMU_BLOCKJOB_TYPE_ACTIVE_COMMIT:
+    case QEMU_BLOCKJOB_TYPE_NONE:
+    case QEMU_BLOCKJOB_TYPE_INTERNAL:
+    case QEMU_BLOCKJOB_TYPE_LAST:
+        break;
+    }
+
+    ret = 0;
+
+ cleanup:
+    for (i = 0; i < njobinfo; i++)
+        qemuMonitorJobInfoFree(jobinfo[i]);
+    VIR_FREE(jobinfo);
+
+    return ret;
+}
+
+
+static void
+qemuBlockJobEventProcess(virQEMUDriverPtr driver,
+                         virDomainObjPtr vm,
+                         qemuBlockJobDataPtr job,
+                         qemuDomainAsyncJob asyncJob)
+
+{
+    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+
+    switch (job->newstate) {
+    case QEMU_BLOCKJOB_STATE_COMPLETED:
+    case QEMU_BLOCKJOB_STATE_FAILED:
+    case QEMU_BLOCKJOB_STATE_CANCELLED:
+    case QEMU_BLOCKJOB_STATE_CONCLUDED:
+        qemuBlockJobEventProcessConcluded(job, driver, vm, asyncJob, cfg);
+        break;
+
+    case QEMU_BLOCKJOB_STATE_READY:
+        if (job->disk && job->disk->mirror) {
+            job->disk->mirrorState = VIR_DOMAIN_BLOCK_JOB_READY;
+            qemuBlockJobEmitEvents(driver, vm, job->disk, job->type, job->newstate);
+        }
+        job->state = job->newstate;
+        break;
+
+    case QEMU_BLOCKJOB_STATE_NEW:
+    case QEMU_BLOCKJOB_STATE_RUNNING:
+    case QEMU_BLOCKJOB_STATE_LAST:
+        goto cleanup;
+    }
+
+    /* write status XML */
+    if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm, driver->caps) < 0)
+        VIR_WARN("Unable to save status on vm %s after block job", vm->def->name);
+
+ cleanup:
+    job->newstate = -1;
+    virObjectUnref(cfg);
+    return;
+}
+
+
 /**
  * qemuBlockJobUpdateDisk:
  * @vm: domain
@@ -411,7 +529,10 @@ qemuBlockJobUpdate(virDomainObjPtr vm,
     if (job->newstate == -1)
         return -1;

-    qemuBlockJobEventProcessLegacy(priv->driver, vm, job, asyncJob);
+    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV))
+        qemuBlockJobEventProcess(priv->driver, vm, job, asyncJob);
+    else
+        qemuBlockJobEventProcessLegacy(priv->driver, vm, job, asyncJob);

     return job->state;
 }
-- 
2.19.2