[libvirt PATCH 14/80] qemu: Keep migration job active after failed post-copy

[Peter Krempa]

On Tue, May 10, 2022 at 17:20:35 +0200, Jiri Denemark wrote:
> When post-copy migration fails, we can't just abort the migration and
> resume the domain on the source host as it is already running on the
> destination host and no host has a complete state of the domain memory.
> Instead of the current approach of just marking the domain on both ends
> as paused/running with a post-copy failed sub state, we will keep the
> migration job active (even though the migration API will return failure)
> so that the state is more visible and we can better control what APIs
> can be called on the domains and even allow for resuming the migration.
> 
> Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
> ---
>  src/qemu/qemu_migration.c | 94 ++++++++++++++++++++++++++++-----------
>  1 file changed, 68 insertions(+), 26 deletions(-)



> @@ -5445,11 +5479,12 @@ qemuMigrationSrcPerformPhase(virQEMUDriver *driver,
>          goto endjob;
>  
>   endjob:
> -    if (ret < 0) {
> +    if (ret < 0 && !virDomainObjIsFailedPostcopy(vm)) {
>          qemuMigrationParamsReset(driver, vm, VIR_ASYNC_JOB_MIGRATION_OUT,
>                                   jobPriv->migParams, priv->job.apiFlags);
>          qemuMigrationJobFinish(vm);
>      } else {
> +        qemuDomainCleanupAdd(vm, qemuProcessCleanupMigrationJob);
>          qemuMigrationJobContinue(vm);
>      }


This logic change is a bit obscure and IMO would benefit from a comment
stating that we want to continue all post-copy migration jobs and all
successful other migrations.


Reviewed-by: Peter Krempa <pkrempa at redhat.com>