[libvirt] [PATCH 1/2] qemu: Cancel migration if guest encoutners I/O error while migrating

[Michal Privoznik]

On 11.06.2013 11:49, Peter Krempa wrote:
> During a live migration the guest may receive a disk access I/O error.
I'd reword this: ... may receive an I/O error while accessing a disk.

> In this state the guest is unable to continue running on a remote host
> after migration as some state may be present in the kernel and not
> migrated.
> 
> With this patch, the migration is canceled in such case so it can either
> continue on the source if the I/O issues are recovered or has to be
> destroyed anyways.
> ---
>  src/qemu/qemu_migration.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index ca79bc2..8e57521 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -1686,6 +1686,7 @@ qemuMigrationWaitForCompletion(virQEMUDriverPtr driver, virDomainObjPtr vm,
>  {
>      qemuDomainObjPrivatePtr priv = vm->privateData;
>      const char *job;
> +    int pauseReason;
> 
>      switch (priv->job.asyncJob) {
>      case QEMU_ASYNC_JOB_MIGRATION_OUT:
> @@ -1707,6 +1708,12 @@ qemuMigrationWaitForCompletion(virQEMUDriverPtr driver, virDomainObjPtr vm,
>          /* Poll every 50ms for progress & to allow cancellation */
>          struct timespec ts = { .tv_sec = 0, .tv_nsec = 50 * 1000 * 1000ull };
> 
> +        /* cancel migration if disk I/O error is emitted while migrating */
> +        if (priv->job.asyncJob == QEMU_ASYNC_JOB_MIGRATION_OUT &&
> +            virDomainObjGetState(vm, &pauseReason) == VIR_DOMAIN_PAUSED &&
> +            pauseReason == VIR_DOMAIN_PAUSED_IOERROR)
> +            goto cancel;
> +
>          if (qemuMigrationUpdateJobStatus(driver, vm, job, asyncJob) < 0)
>              goto cleanup;
> 
> @@ -1728,6 +1735,20 @@ cleanup:
>          return 0;
>      else
>          return -1;
> +
> +cancel:
> +    if (virDomainObjIsActive(vm)) {
> +        if (qemuDomainObjEnterMonitorAsync(driver, vm,
> +                                           priv->job.asyncJob) == 0) {
> +            qemuMonitorMigrateCancel(priv->mon);
> +            qemuDomainObjExitMonitor(driver, vm);
> +        }
> +    }
> +
> +    priv->job.info.type = VIR_DOMAIN_JOB_FAILED;
> +    virReportError(VIR_ERR_OPERATION_FAILED,
> +                   _("%s: %s"), job, _("failed due to I/O error"));
> +    return -1;
>  }
> 
> 

ACK

Michal