Re: [Qemu-devel] [PATCH 06/11] qmp: Add an implementation wrapper for qmp_drive_backup

[John Snow <jsnow@redhat.com>]

On 03/17/2015 02:51 PM, Max Reitz wrote:
> On 2015-03-04 at 23:15, John Snow wrote:
>> We'd like to be able to specify the callback given to backup_start
>> manually in the case of transactions, so split apart qmp_drive_backup
>> into an implementation and a wrapper.
>>
>> Switch drive_backup_prepare to use the new wrapper, but don't overload
>> the callback and closure yet.
>>
>> This is kind of gross, but we need to forward-declare the wrapper for
>> the drive_backup transaction to be able to use. I could try moving
>> the transaction blocks lower instead, but I wanted (for v1, at least)
>> to minimize code movement so that the core changes were easiest to see.
>>
>> If anyone has suggestions on organization, please suggest them.
>>
>> Signed-off-by: John Snow <jsnow@redhat.com>
>> ---
>>   blockdev.c | 77
>> ++++++++++++++++++++++++++++++++++++++++++++++----------------
>>   1 file changed, 58 insertions(+), 19 deletions(-)
>>
>> diff --git a/blockdev.c b/blockdev.c
>> index 3153ee7..9e3b9e9 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
>> @@ -1449,6 +1449,19 @@ void
>> undo_transaction_wrapper(BlkTransactionState *common)
>>       blk_put_transaction_state(common);
>>   }
>> +static void _drive_backup(const char *device, const char *target,
>
> Please don't use leading underscores. (Please.)
>
> Just call it do_drive_backup() or something.
>
> Other than that, I'm okay with a forward-declaration; if you want to
> move it, but I'd be fine with moving the code, too.
>
> With _drive_backup() being called do_drive_backup():
>
> Reviewed-by: Max Reitz <mreitz@redhat.com>
>

Moving the code around might be better, it just makes for a much noisier 
patch. I made my decisions for v1 to keep code disturbed the least.

Once more critiques roll in I will decide what to do.

I'll replace with "do_drive_backup" unless you can think of a nice 
three-letter word to replace "do" so that I don't even have to perturb 
the alignment context ;)

>> +                          bool has_format, const char *format,
>> +                          enum MirrorSyncMode sync,
>> +                          bool has_mode, enum NewImageMode mode,
>> +                          bool has_speed, int64_t speed,
>> +                          bool has_bitmap, const char *bitmap,
>> +                          bool has_on_source_error,
>> +                          BlockdevOnError on_source_error,
>> +                          bool has_on_target_error,
>> +                          BlockdevOnError on_target_error,
>> +                          BlockCompletionFunc *cb, void *opaque,
>> +                          Error **errp);
>> +
>>   /* internal snapshot private data */
>>   typedef struct InternalSnapshotState {
>>       BlkTransactionState common;
>> @@ -1768,15 +1781,16 @@ static void
>> drive_backup_prepare(BlkTransactionState *common, Error **errp)
>>       state->aio_context = bdrv_get_aio_context(bs);
>>       aio_context_acquire(state->aio_context);
>> -    qmp_drive_backup(backup->device, backup->target,
>> -                     backup->has_format, backup->format,
>> -                     backup->sync,
>> -                     backup->has_mode, backup->mode,
>> -                     backup->has_speed, backup->speed,
>> -                     backup->has_bitmap, backup->bitmap,
>> -                     backup->has_on_source_error,
>> backup->on_source_error,
>> -                     backup->has_on_target_error,
>> backup->on_target_error,
>> -                     &local_err);
>> +    _drive_backup(backup->device, backup->target,
>> +                  backup->has_format, backup->format,
>> +                  backup->sync,
>> +                  backup->has_mode, backup->mode,
>> +                  backup->has_speed, backup->speed,
>> +                  backup->has_bitmap, backup->bitmap,
>> +                  backup->has_on_source_error, backup->on_source_error,
>> +                  backup->has_on_target_error, backup->on_target_error,
>> +                  NULL, NULL,
>> +                  &local_err);
>>       if (local_err) {
>>           error_propagate(errp, local_err);
>>           return;
>> @@ -2717,15 +2731,18 @@ out:
>>       aio_context_release(aio_context);
>>   }
>> -void qmp_drive_backup(const char *device, const char *target,
>> -                      bool has_format, const char *format,
>> -                      enum MirrorSyncMode sync,
>> -                      bool has_mode, enum NewImageMode mode,
>> -                      bool has_speed, int64_t speed,
>> -                      bool has_bitmap, const char *bitmap,
>> -                      bool has_on_source_error, BlockdevOnError
>> on_source_error,
>> -                      bool has_on_target_error, BlockdevOnError
>> on_target_error,
>> -                      Error **errp)
>> +static void _drive_backup(const char *device, const char *target,
>> +                          bool has_format, const char *format,
>> +                          enum MirrorSyncMode sync,
>> +                          bool has_mode, enum NewImageMode mode,
>> +                          bool has_speed, int64_t speed,
>> +                          bool has_bitmap, const char *bitmap,
>> +                          bool has_on_source_error,
>> +                          BlockdevOnError on_source_error,
>> +                          bool has_on_target_error,
>> +                          BlockdevOnError on_target_error,
>> +                          BlockCompletionFunc *cb, void *opaque,
>> +                          Error **errp)
>>   {
>>       BlockDriverState *bs;
>>       BlockDriverState *target_bs;
>> @@ -2837,9 +2854,15 @@ void qmp_drive_backup(const char *device, const
>> char *target,
>>           }
>>       }
>> +    if (cb == NULL) {
>> +        cb = block_job_cb;
>> +    }
>> +    if (opaque == NULL) {
>> +        opaque = bs;
>> +    }
>>       backup_start(bs, target_bs, speed, sync, bmap,
>>                    on_source_error, on_target_error,
>> -                 block_job_cb, bs, &local_err);
>> +                 cb, opaque, &local_err);
>>       if (local_err != NULL) {
>>           bdrv_unref(target_bs);
>>           error_propagate(errp, local_err);
>> @@ -2850,6 +2873,22 @@ out:
>>       aio_context_release(aio_context);
>>   }
>> +void qmp_drive_backup(const char *device, const char *target,
>> +                      bool has_format, const char *format,
>> +                      enum MirrorSyncMode sync,
>> +                      bool has_mode, enum NewImageMode mode,
>> +                      bool has_speed, int64_t speed,
>> +                      bool has_bitmap, const char *bitmap,
>> +                      bool has_on_source_error, BlockdevOnError
>> on_source_error,
>> +                      bool has_on_target_error, BlockdevOnError
>> on_target_error,
>> +                      Error **errp)
>> +{
>> +    _drive_backup(device, target, has_format, format, sync, has_mode,
>> mode,
>> +                  has_speed, speed, has_bitmap, bitmap,
>> has_on_source_error,
>> +                  on_source_error, has_on_target_error, on_target_error,
>> +                  NULL, NULL, errp);
>> +}
>> +
>>   BlockDeviceInfoList *qmp_query_named_block_nodes(Error **errp)
>>   {
>>       return bdrv_named_nodes_list();
>