Re: [Qemu-devel] [PATCH v4 06/11] block: add refcount to Job object

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, May 11, 2015 at 07:04:21PM -0400, John Snow wrote:
> If we want to get at the job after the life of the job,
> we'll need a refcount for this object.
> 
> This may occur for example if we wish to inspect the actions
> taken by a particular job after a transactional group of jobs
> runs, and further actions are required.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>
> ---
>  blockjob.c               | 18 ++++++++++++++++--
>  include/block/blockjob.h | 21 +++++++++++++++++++++
>  2 files changed, 37 insertions(+), 2 deletions(-)

I think the only reason for this refcount is so that
backup_transaction_complete() can be called.  It accesses
BackupBlockJob->sync_bitmap so the BackupBlockJob instance needs to be
alive.

The bitmap refcount is incremented in blockdev.c, not block/backup.c, so
it is fine to drop backup_transaction_complete() and decrement the
bitmap refcount in blockdev.c instead.

If you do that then there is no need to add a refcount to block job.
This would simplify things.

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