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

[Max Reitz <mreitz@redhat.com>]

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>

> +                          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();