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Date: Tue, 26 May 2015 11:30:14 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 1/8] block: Add "base" option to
	bdrv_get_block_status
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, Jeff Cody <jcody@redhat.com>, qemu-devel@nongnu.org, qemu-stable@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, jsnow@redhat.com, wangxiaolong@ucloud.cn

On Mon, 05/25 16:43, Paolo Bonzini wrote:
> 
> 
> On 22/05/2015 05:40, Fam Zheng wrote:
> > +{
> > +    BlockDriverState *p;
> > +    int64_t ret;
> > +
> > +    assert(bs != base);
> > +    for (p = bs; p != base; p = p->backing_hd) {
> > +        ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum);
> 
> It's a bit ugly to have different parameters for bdrv_get_block_status
> and bdrv_co_get_block_status.

I'll add bdrv_get_block_status_above and rewrite bdrv_get_block_status body on
top.

> 
> > +        if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
> > +            break;
> > +        }
> > +    }
> > +    return ret;
> > +}
> > +
> 
> I think BDRV_BLOCK_ALLOCATED will always be true if passing NULL as the
> base, so patch 3 still needs a tweak.

OK, will use BDRV_BLOCK_DATA there.

> 
> But, more important, you need extra logic to correct the output value of
> pnum, as in bdrv_is_allocated_above.

bdrv_co_get_block_status should fix pnum.

Fam