[libvirt] [PATCH 18/25] qemu: blockjob: Add modern block job event handler

[Ján Tomko]

On Fri, Jul 12, 2019 at 06:05:59PM +0200, Peter Krempa wrote:
>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 | 168 ++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 167 insertions(+), 1 deletion(-)
>
>diff --git a/src/qemu/qemu_blockjob.c b/src/qemu/qemu_blockjob.c
>index dd6071dae1..8b142f1aba 100644
>--- a/src/qemu/qemu_blockjob.c
>+++ b/src/qemu/qemu_blockjob.c
>+static void
>+qemuBlockJobEventProcessConcluded(qemuBlockJobDataPtr job,
>+                                  virQEMUDriverPtr driver,
>+                                  virDomainObjPtr vm,
>+                                  qemuDomainAsyncJob asyncJob)
>+{
>+    qemuMonitorJobInfoPtr *jobinfo = NULL;
>+    size_t njobinfo = 0;
>+    size_t i;
>+    int rc = 0;
>+    bool dismissed = false;
>+    bool refreshed = false;
>+
>+    if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
>+        goto cleanup;
>+
>+    /* we need to fetch the error state as the event does not propagate it */
>+    if (job->newstate == QEMU_BLOCKJOB_STATE_CONCLUDED &&
>+        (rc = qemuMonitorGetJobInfo(qemuDomainGetMonitor(vm), &jobinfo, &njobinfo)) == 0) {
>+
>+        for (i = 0; i < njobinfo; i++) {
>+            if (STRNEQ_NULLABLE(job->name, jobinfo[i]->id))
>+                continue;
>+
>+            if (VIR_STRDUP(job->errmsg, jobinfo[i]->error) < 0)
>+                rc = -1;
>+
>+            if (job->errmsg)
>+                job->newstate = QEMU_BLOCKJOB_STATE_FAILED;
>+            else
>+                job->newstate = QEMU_BLOCKJOB_STATE_COMPLETED;
>+
>+            refreshed = true;
>+
>+            break;
>+        }
>+
>+        if (i == njobinfo) {
>+            VIR_WARN("failed to refresh job '%s'", job->name);
>+            rc = -1;
>+        }
>+    }
>+
>+    /* dismiss job in qemu */
>+    if (rc >= 0) {
>+        if ((rc = qemuMonitorJobDismiss(qemuDomainGetMonitor(vm), job->name)) >= 0)
>+            dismissed = true;
>+    }
>+
>+    if (job->invalidData) {
>+        VIR_WARN("terminating job '%s' with invalid data", job->name);
>+        goto cleanup;
>+    }
>+
>+    if (qemuDomainObjExitMonitor(driver, vm) < 0 || rc < 0)
>+        goto cleanup;
>+
>+    if (refreshed)
>+        qemuDomainSaveStatus(vm);
>+
>+    VIR_DEBUG("handling job '%s' state '%d' newstate '%d'", job->name, job->state, job->newstate);
>+
>+    qemuBlockJobEventProcessConcludedTransition(job, driver, vm, asyncJob);
>+
>+ cleanup:
>+    if (dismissed) {
>+        qemuBlockJobUnregister(job, vm);
>+        job = NULL;

job is a local parameter here so this statement has no real effect.
Moreover, I'd expect that the caller of the function still holds a
reference.

>+        qemuDomainSaveConfig(vm);
>+    }
>+
>+    for (i = 0; i < njobinfo; i++)
>+        qemuMonitorJobInfoFree(jobinfo[i]);
>+    VIR_FREE(jobinfo);
>+}
>+
>+

Reviewed-by: Ján Tomko <jtomko at redhat.com>

Jano
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