Re: [Qemu-devel] [PATCH v3 01/15] block: Add "file" output parameter to block status query functions

[Stefan Hajnoczi]

On Mon, Nov 30, 2015 at 05:09:49PM +0800, Fam Zheng wrote:
> On Mon, 11/30 16:38, Stefan Hajnoczi wrote:
> > On Thu, Nov 26, 2015 at 01:05:21PM +0800, Fam Zheng wrote:
> > > @@ -1535,13 +1541,14 @@ static int64_t coroutine_fn 
> > > bdrv_co_get_block_status(BlockDriverState *bs,
> > >          }
> > >      }
> > >  
> > > -    if (bs->file &&
> > > +    if (*file && *file != bs &&
> > >          (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
> > >          (ret & BDRV_BLOCK_OFFSET_VALID)) {
> > 
> > What is the purpose of this change?
> 
> The code here is to sensibly detect "zero" by going into the "file" which the
> offset is valid for. Now the "file" is no longer always "bs->file", so we use
> the returned "file" pointer instead.

Thanks for explaining!

Stefan

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