Re: [Qemu-devel] [PATCH COLO v3 11/14] Backup: clear all bitmap when doing block checkpoint

[Wen Congyang <wency@cn.fujitsu.com>]

On 04/03/2015 07:09 PM, Paolo Bonzini wrote:
> 
> 
> On 03/04/2015 12:01, Wen Congyang wrote:
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>> Cc: Jeff Cody <jcody@redhat.com>
>> ---
>>  block/backup.c           | 13 +++++++++++++
>>  blockjob.c               | 10 ++++++++++
>>  include/block/blockjob.h | 12 ++++++++++++
>>  3 files changed, 35 insertions(+)
>>
>> diff --git a/block/backup.c b/block/backup.c
>> index 1c535b1..e8b8931 100644
>> --- a/block/backup.c
>> +++ b/block/backup.c
>> @@ -208,11 +208,24 @@ static void backup_iostatus_reset(BlockJob *job)
>>      bdrv_iostatus_reset(s->target);
>>  }
>>  
>> +static void backup_do_checkpoint(BlockJob *job, Error **errp)
>> +{
>> +    BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
>> +
>> +    if (backup_job->sync_mode != MIRROR_SYNC_MODE_NONE) {
>> +        error_setg(errp, "this feature or command is not currently supported");
>> +        return;
>> +    }
>> +
>> +    hbitmap_reset_all(backup_job->bitmap);
>> +}
>> +
>>  static const BlockJobDriver backup_job_driver = {
>>      .instance_size  = sizeof(BackupBlockJob),
>>      .job_type       = BLOCK_JOB_TYPE_BACKUP,
>>      .set_speed      = backup_set_speed,
>>      .iostatus_reset = backup_iostatus_reset,
>> +    .do_checkpoint  = backup_do_checkpoint,
>>  };
>>  
>>  static BlockErrorAction backup_error_action(BackupBlockJob *job,
>> diff --git a/blockjob.c b/blockjob.c
>> index ba2255d..dbac81e 100644
>> --- a/blockjob.c
>> +++ b/blockjob.c
>> @@ -388,3 +388,13 @@ void block_job_defer_to_main_loop(BlockJob *job,
>>  
>>      qemu_bh_schedule(data->bh);
>>  }
>> +
>> +void block_job_do_checkpoint(BlockJob *job, Error **errp)
>> +{
>> +    if (!job->driver->do_checkpoint) {
>> +        error_setg(errp, "this feature or command is not currently supported");
>> +        return;
>> +    }
>> +
>> +    job->driver->do_checkpoint(job, errp);
>> +}
>> diff --git a/include/block/blockjob.h b/include/block/blockjob.h
>> index b6d4ebb..c6f1cad 100644
>> --- a/include/block/blockjob.h
>> +++ b/include/block/blockjob.h
>> @@ -50,6 +50,9 @@ typedef struct BlockJobDriver {
>>       * manually.
>>       */
>>      void (*complete)(BlockJob *job, Error **errp);
>> +
>> +    /** Optional callback for job types that support checkpoint. */
>> +    void (*do_checkpoint)(BlockJob *job, Error **errp);
>>  } BlockJobDriver;
>>  
>>  /**
>> @@ -334,4 +337,13 @@ void block_job_defer_to_main_loop(BlockJob *job,
>>                                    BlockJobDeferToMainLoopFn *fn,
>>                                    void *opaque);
>>  
>> +/**
>> + * block_job_do_checkpoint:
>> + * @job: The job.
>> + * @errp: Error object.
>> + *
>> + * Do block checkpoint on the specified job.
>> + */
>> +void block_job_do_checkpoint(BlockJob *job, Error **errp);
>> +
>>  #endif
>>
> 
> Does this only run on the secondary, or also on the primary?  What
> happens if you use a block job on the primary?

It is only for secondary. This new blockjob API is only called in qcow2+colo,
which is used for secondary qemu. So primary qemu will not come here.
If it happens, it is a bug. Should we check it here?

Thanks
Wen Congyang

> 
> Perhaps a variant of backup_job_driver is needed for COLO, and the
> default behavior of block_job_do_checkpoint should be to do nothing?
> 
> Paolo
> .
>