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

[Peter Lieven]

On 13.09.2013 11:10, Paolo Bonzini wrote:
> Il 13/09/2013 11:08, Peter Lieven ha scritto:
> > 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?
> Correct but a bit hackish... Stefan, Kevin, any ideas?
add a BDRV_BLOCK_RAW flag to the get_block_status flags?