Re: [Qemu-devel] [PATCH 07/24] qcow2: add bitmaps extension

[Vladimir Sementsov-Ogievskiy]

29.01.2017 00:29, Max Reitz wrote:
> On 23.01.2017 13:10, Vladimir Sementsov-Ogievskiy wrote:
> > Add bitmap extension as specified in docs/specs/qcow2.txt.
> > For now, just mirror extension header into Qcow2 state and check
> > constraints.
> >
> > For now, disable image resize if it has bitmaps. It will be fixed later.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > ---
> >   block/qcow2.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> >   block/qcow2.h |  24 ++++++++++++
> >   2 files changed, 141 insertions(+), 2 deletions(-)
> >
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index 96fb8a8f16..a8835988c7 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
> [...]
>
> > @@ -185,6 +265,15 @@ static int qcow2_read_extensions(BlockDriverState *bs, 
> > uint64_t start_offset,
> >           offset += ((ext.len + 7) & ~7);
> >       }
> >   
> > +    if (need_update && !bdrv_is_root_node(bs) &&
> > +        !(bdrv_get_flags(bs) & BDRV_O_INACTIVE))
> > +    {
> > +        ret = qcow2_update_header(bs);
> Good idea, but qcow2_read_extensions() can be called pretty early in
> qcow2_open(). Therefore, some fields in the BDRVQcow2State are not
> necessarily set already.
>
> For instance, it is always called before s->snapshots_offset and
> s->nb_snapshots are set. Thus, this will effectively always discard all
> snapshots.
>
> Max

So, I need to move need_update to qcow2_read_extensions parameters as 
'bool *' and handle it later, in the end of qcow2_open. Ok?



--
Best regards,
Vladimir