Re: [Qemu-devel] [PATCH v4 4/4] migration: Expose 'cancelling' status to user

[Paolo Bonzini <pbonzini@redhat.com>]

On 09/03/2015 07:45, zhanghailiang wrote:
> 'cancelling' status was introduced by commit 51cf4c1a, mainly to avoid a 
> possible start of a new migration process while the previous one still exists.
> But we didn't expose this status to user, instead we returned the 'active' state.
> 
> Here, we expose it to the user (such as libvirt), 'cancelling' status only
> occurs for a short window before the migration aborts, so for users,
> if they cancel a migration process, it will observe 'cancelling' status
> occasionally.
> 
> Testing revealed that with older libvirt (anything 1.2.13 or less) will
> print an odd error message if the state is seen, but that the migration
> is still properly cancelled. Newer libvirt will be patched to recognize
> the new state without the odd error message.
> 
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Cc: libvir-list@redhat.com

Why is this necessary?

Paolo

> ---
>  migration/migration.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 035e005..a57928d 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -179,13 +179,11 @@ MigrationInfo *qmp_query_migrate(Error **errp)
>          break;
>      case MIGRATION_STATUS_SETUP:
>          info->has_status = true;
> -        info->status = MIGRATION_STATUS_SETUP;
>          info->has_total_time = false;
>          break;
>      case MIGRATION_STATUS_ACTIVE:
>      case MIGRATION_STATUS_CANCELLING:
>          info->has_status = true;
> -        info->status = MIGRATION_STATUS_ACTIVE;
>          info->has_total_time = true;
>          info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
>              - s->total_time;
> @@ -221,7 +219,6 @@ MigrationInfo *qmp_query_migrate(Error **errp)
>          get_xbzrle_cache_stats(info);
>  
>          info->has_status = true;
> -        info->status = MIGRATION_STATUS_COMPLETED;
>          info->has_total_time = true;
>          info->total_time = s->total_time;
>          info->has_downtime = true;
> @@ -243,13 +240,12 @@ MigrationInfo *qmp_query_migrate(Error **errp)
>          break;
>      case MIGRATION_STATUS_FAILED:
>          info->has_status = true;
> -        info->status = MIGRATION_STATUS_FAILED;
>          break;
>      case MIGRATION_STATUS_CANCELLED:
>          info->has_status = true;
> -        info->status = MIGRATION_STATUS_CANCELLED;
>          break;
>      }
> +    info->status = s->state;
>  
>      return info;
>  }
>