Re: [Qemu-devel] [PATCH V4 1/3] block: Add bdrv_are_busy()

[Luiz Capitulino <lcapitulino@redhat.com>]

On Tue, 24 Jul 2012 12:10:39 +0200
Benoît Canet <benoit.canet@irqsave.net> wrote:

> Le Monday 23 Jul 2012 à 14:15:01 (-0300), Luiz Capitulino a écrit :
> > On Mon, 23 Jul 2012 16:22:58 +0200
> > benoit.canet@gmail.com wrote:
> > 
> > > From: Benoît Canet <benoit@irqsave.net>
> > > 
> > > bdrv_are_busy will be used to check if any of the bs are in use
> > > or if one of them have a running block job.
> > > 
> > > The first user will be qmp_migrate().
> > > 
> > > Signed-off-by: Benoit Canet <benoit@irqsave.net>
> > > ---
> > >  block.c |   13 +++++++++++++
> > >  block.h |    2 ++
> > >  2 files changed, 15 insertions(+)
> > > 
> > > diff --git a/block.c b/block.c
> > > index ce7eb8f..bc8f160 100644
> > > --- a/block.c
> > > +++ b/block.c
> > > @@ -4027,6 +4027,19 @@ out:
> > >      return ret;
> > >  }
> > >  
> > > +int bdrv_are_busy(void)
> > > +{
> > > +    BlockDriverState *bs;
> > > +
> > > +    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > > +        if (bs->job || bdrv_in_use(bs)) {
> > > +            return -EBUSY;
> > > +        }
> > > +    }
> > 
> > IMO, this should return true/false. The name is a bit misleading too, as it
> > gives the impression that are existing bdrvs are busy. I'd call it
> > bdrv_any_busy() or bdrv_any_in_use().
> 
> Hello Anthony,
> 
> Stefanha is in favor of returning -EBUSY and Luiz Capitulino would prefer
> the function to return a boolean.
> Could you decide which option is the best ?

Stefan's opnion certainly has precedence over mine on block layer stuff,
this was just an IMO.

Stefan, did you consider returning a boolean?

> 
> Regards
> 
> Benoît
> 
> > 
> > > +
> > > +    return 0;
> > > +}
> > > +
> > >  void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
> > >                         int64_t speed, BlockDriverCompletionFunc *cb,
> > >                         void *opaque, Error **errp)
> > > diff --git a/block.h b/block.h
> > > index c89590d..0a3de2f 100644
> > > --- a/block.h
> > > +++ b/block.h
> > > @@ -337,6 +337,8 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs);
> > >  void bdrv_set_in_use(BlockDriverState *bs, int in_use);
> > >  int bdrv_in_use(BlockDriverState *bs);
> > >  
> > > +int bdrv_are_busy(void);
> > > +
> > >  enum BlockAcctType {
> > >      BDRV_ACCT_READ,
> > >      BDRV_ACCT_WRITE,
> > 
>