Re: [Qemu-devel] [PATCH v7 05/10] block: Introduce "drained begin/end" API

[Fam Zheng]

On Fri, 10/23 16:24, Stefan Hajnoczi wrote:
> On Fri, Oct 23, 2015 at 11:08:09AM +0800, Fam Zheng wrote:
> > +/**
> > + * bdrv_drained_begin:
> > + *
> > + * Begin a quiesced section for exclusive access to the BDS, by disabling
> > + * external request sources including NBD server and device model. Note 
> > that
> > + * this doesn't block timers or coroutines from submitting more requests, 
> > which
> > + * means block_job_pause is still necessary.
> 
> How is the 'transaction' command protected from block jobs?  Maybe I
> missed a block_job_pause() call that you added in this series...

There is no block job that can change guest visible data now, and we don't
support multiple block jobs on one BDS. That's why a call wasn't added in this
series. The comment actually is speaking generally for potential callers other
than qmp_transaction.

Fam