Re: [Qemu-devel] [PATCH V15 03/13] quorum: Add quorum_aio_writev and its dependencies.

["Benoît Canet" <benoit.canet@irqsave.net>]

Le Tuesday 04 Feb 2014 à 14:57:22 (+0100), Kevin Wolf a écrit :
> Am 03.02.2014 um 22:51 hat Benoît Canet geschrieben:
> > From: Benoît Canet <benoit@irqsave.net>
> > 
> > Signed-off-by: Benoit Canet <benoit@irqsave.net>
> > ---
> >  block/quorum.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 104 insertions(+)
> 
> Starting with writes before the driver can even open an image is a weird
> order to do things in. It also doesn't make the review any easier when
> you don't know how things are initialised.
I have done it in this way for better git bisectability: if the driver cannot
open the quorum the commit is a preparation work that should be excluded of git
bisect commit range.

For the write before read order it's this way because quorum writes are simpler.

Best regards

Benoît

> 
> > diff --git a/block/quorum.c b/block/quorum.c
> > index 157efdf..81bffdd 100644
> > --- a/block/quorum.c
> > +++ b/block/quorum.c
> > @@ -64,11 +64,115 @@ struct QuorumAIOCB {
> >      int vote_ret;
> >  };
> >  
> > +static void quorum_aio_cancel(BlockDriverAIOCB *blockacb)
> > +{
> > +    QuorumAIOCB *acb = container_of(blockacb, QuorumAIOCB, common);
> > +    BDRVQuorumState *s = acb->bqs;
> > +    int i;
> > +
> > +    /* cancel all callback */
> 
> "callbacks"
> 
> > +    for (i = 0; i < s->total; i++) {
> > +        bdrv_aio_cancel(acb->aios[i].aiocb);
> > +    }
> > +}
> 
> Don't you want to free acb and similar cleanup?
> 
> > +
> > +static AIOCBInfo quorum_aiocb_info = {
> > +    .aiocb_size         = sizeof(QuorumAIOCB),
> > +    .cancel             = quorum_aio_cancel,
> > +};
> > +
> > +static void quorum_aio_finalize(QuorumAIOCB *acb)
> > +{
> > +    BDRVQuorumState *s = acb->bqs;
> 
> block/quorum.c: In function 'quorum_aio_finalize':
> block/quorum.c:86:22: error: unused variable 's' [-Werror=unused-variable]
> 
> > +    int ret = 0;
> > +
> > +    acb->common.cb(acb->common.opaque, ret);
> > +    if (acb->finished) {
> > +        *acb->finished = true;
> > +    }
> > +    g_free(acb->aios);
> > +    qemu_aio_release(acb);
> > +}
> > +
> > +static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s,
> > +                                   BlockDriverState *bs,
> > +                                   QEMUIOVector *qiov,
> > +                                   uint64_t sector_num,
> > +                                   int nb_sectors,
> > +                                   BlockDriverCompletionFunc *cb,
> > +                                   void *opaque)
> > +{
> > +    QuorumAIOCB *acb = qemu_aio_get(&quorum_aiocb_info, bs, cb, opaque);
> > +    int i;
> > +
> > +    acb->bqs = s;
> 
> Noticed it only here, but it's really in patch 2 (and should be in
> patch 1):
> 
> What is acb->bqs good for? Isn't it always the same as
> acb->common.bs->opaque?
> 
> > +    acb->sector_num = sector_num;
> > +    acb->nb_sectors = nb_sectors;
> > +    acb->qiov = qiov;
> > +    acb->aios = g_new0(QuorumSingleAIOCB, s->total);
> > +    acb->count = 0;
> > +    acb->success_count = 0;
> > +    acb->finished = NULL;
> > +    acb->is_read = false;
> > +    acb->vote_ret = 0;
> > +
> > +    for (i = 0; i < s->total; i++) {
> > +        acb->aios[i].buf = NULL;
> > +        acb->aios[i].ret = 0;
> > +        acb->aios[i].parent = acb;
> > +    }
> >
> > +
> > +    return acb;
> > +}
> 
> Kevin