Re: [Qemu-devel] [PATCH 2/8] block: add driver operation callbacks

[Benoît Canet]

The Monday 01 Sep 2014 à 17:19:19 (+0800), Liu Yuan wrote :
> On Mon, Sep 01, 2014 at 10:28:54AM +0200, Benoît Canet wrote:
> > The Monday 01 Sep 2014 à 15:43:08 (+0800), Liu Yuan wrote :
> > > Driver operations are defined as callbacks passed from block upper 
> > > drivers to
> > > lower drivers and are supposed to be called by lower drivers.
> > > 
> > > Requests handling(queuing, submitting, etc.) are done in protocol tier in 
> > > the
> > > block layer and connection states are also maintained down there. Driver
> > > operations are supposed to notify the upper tier (such as quorum) of the 
> > > states
> > > changes.
> > > 
> > > For now only two operation are added:
> > > 
> > > driver_disconnect: called when connection is off
> > > driver_reconnect: called when connection is on after disconnection
> > > 
> > > Which are used to notify upper tier of the connection state.
> > > 
> > > Cc: Eric Blake <address@hidden>
> > > Cc: Benoit Canet <address@hidden>
> > > Cc: Kevin Wolf <address@hidden>
> > > Cc: Stefan Hajnoczi <address@hidden>
> > > Signed-off-by: Liu Yuan <address@hidden>
> > > ---
> > >  block.c                   | 7 +++++++
> > >  include/block/block.h     | 7 +++++++
> > >  include/block/block_int.h | 3 +++
> > >  3 files changed, 17 insertions(+)
> > > 
> > > diff --git a/block.c b/block.c
> > > index c12b8de..22eb3e4 100644
> > > --- a/block.c
> > > +++ b/block.c
> > > @@ -2152,6 +2152,13 @@ void bdrv_set_dev_ops(BlockDriverState *bs, const 
> > > BlockDevOps *ops,
> > >      bs->dev_opaque = opaque;
> > >  }
> > >  
> > > +void bdrv_set_drv_ops(BlockDriverState *bs, const BlockDrvOps *ops,
> > > +                      void *opaque)
> > > +{
> > > +    bs->drv_ops = ops;
> > > +    bs->drv_opaque = opaque;
> > 
> > We need to be very carefull of the mix between these fields and the infamous
> > bdrv_swap function.
> > 
> > Also I don't know if "driver operations" is the right name since the 
> > BlockDriver structure's
> > callback could also be named "driver operations".
> > 
> 
> BlockDrvierState has a "device operation" for callbacks from devices. So I
> choose "driver operation". So any sugguestion for better name?

>From what I see in this series the job of these callbacks is to send a message 
>or a signal to
the upper BDS.

Also the name must reflect it goes from the child to the parent.

child_signals ?
child_messages ?

Best regards

Benoît

> 
> Thanks
> Yuan
>