Re: [Qemu-devel] [PATCH v4 10/14] blockdev: make BlockJobTxn available to qmp 'transaction'

[Max Reitz <mreitz@redhat.com>]

On 30.07.2015 08:39, Fam Zheng wrote:
> From: Stefan Hajnoczi <stefanha@redhat.com>
>
> Provide a BlockJobTxn to actions executed in a qmp 'transaction'
> command.  This allows actions to make their block jobs either complete
> as a group or fail/cancel together.
>
> The next patch adds the first user.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Reviewed-by: Fam Zheng <famz@redhat.com>
> Reviewed-by: John Snow <jsnow@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>   blockdev.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/blockdev.c b/blockdev.c
> index 2eb4f34..aba9d78 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1279,6 +1279,7 @@ typedef struct BlkActionOps {
>   struct BlkActionState {
>       TransactionAction *action;
>       const BlkActionOps *ops;
> +    BlockJobTxn *block_job_txn;
>       QSIMPLEQ_ENTRY(BlkActionState) entry;
>   };
>
> @@ -1883,12 +1884,15 @@ static const BlkActionOps actions[] = {
>   void qmp_transaction(TransactionActionList *dev_list, Error **errp)
>   {
>       TransactionActionList *dev_entry = dev_list;
> +    BlockJobTxn *block_job_txn;
>       BlkActionState *state, *next;
>       Error *local_err = NULL;
>
>       QSIMPLEQ_HEAD(snap_bdrv_states, BlkActionState) snap_bdrv_states;
>       QSIMPLEQ_INIT(&snap_bdrv_states);
>
> +    block_job_txn = block_job_txn_new();
> +
>       /* drain all i/o before any operations */
>       bdrv_drain_all();
>
> @@ -1908,6 +1912,7 @@ void qmp_transaction(TransactionActionList *dev_list, Error **errp)
>           state = g_malloc0(ops->instance_size);
>           state->ops = ops;
>           state->action = dev_info;
> +        state->block_job_txn = block_job_txn;
>           QSIMPLEQ_INSERT_TAIL(&snap_bdrv_states, state, entry);
>
>           state->ops->prepare(state, &local_err);
>

And then state->block_job_txn is never used, thus leaked. I guess this 
is fixed for backup jobs in the next patch (by "The transaction is 
automatically freed when the last job completes or is cancelled"), but 
for any transaction which doesn't contain any block job which is added 
to the transaction, it probably remains leaked.

Max