Re: [Qemu-devel] [PULL 39/42] block: look for zero blocks in bs->file

[Peter Lieven]

On 13.09.2013 10:00, Peter Lieven wrote:
> On 06.09.2013 17:39, Stefan Hajnoczi wrote:
> > From: Paolo Bonzini <address@hidden>
> >
> > Reviewed-by: Eric Blake <address@hidden>
> > Signed-off-by: Paolo Bonzini <address@hidden>
> > Signed-off-by: Stefan Hajnoczi <address@hidden>
> > ---
> >   block.c | 16 +++++++++++++++-
> >   1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/block.c b/block.c
> > index 3c39769..a325efc 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -3075,7 +3075,7 @@ static int64_t coroutine_fn 
> > bdrv_co_get_block_status(BlockDriverState *bs,
> >   {
> >       int64_t length;
> >       int64_t n;
> > -    int64_t ret;
> > +    int64_t ret, ret2;
> >         length = bdrv_getlength(bs);
> >       if (length < 0) {
> > @@ -3117,6 +3117,20 @@ static int64_t coroutine_fn 
> > bdrv_co_get_block_status(BlockDriverState *bs,
> >               }
> >           }
> >       }
> > +
> > +    if (bs->file &&
> > +        (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
> > +        (ret & BDRV_BLOCK_OFFSET_VALID)) {
> > +        ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
> > +                                        *pnum, pnum);
> > +        if (ret2 >= 0) {
> > +            /* Ignore errors.  This is just providing extra information, it
> > +             * is useful but not necessary.
> > +             */
> > +            ret |= (ret2 & BDRV_BLOCK_ZERO);
> > +        }
> > +    }
> > +
> >       return ret;
> >   }
> for allocated blocks in iscsi this actually leads to 2 call outs to 
> iscsi_get_block_status.
>
> because the raw driver passes the get_block_status request to bs->file.
correct patch?

@@ -3119,9 +3167,8 @@ static int64_t coroutine_fn 
bdrv_co_get_block_status(BlockDriverState *bs,
         }
     }

-    if (bs->file &&
-        (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
-        (ret & BDRV_BLOCK_OFFSET_VALID)) {
+    if (bs->file && (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
+        (ret & BDRV_BLOCK_OFFSET_VALID) && bs->drv != bdrv_find_format("raw")) 
{
         ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
                                         *pnum, pnum);
         if (ret2 >= 0) {