> -----Original Message----- > From: Paolo Bonzini [mailto:pbonz...@redhat.com] > Sent: Wednesday, September 21, 2016 6:37 PM > To: Pavel Dovgalyuk; qemu-devel@nongnu.org > Cc: peter.mayd...@linaro.org; jasow...@redhat.com; quint...@redhat.com; > m...@redhat.com > Subject: Re: [PATCH v4 3/8] block: don't make snapshots for filters > > > > On 21/09/2016 13:33, Pavel Dovgalyuk wrote: > > This patch disables snapshotting for block driver filters. > > It is needed, because snapshots should be created > > in underlying disk images, not in filters itself. > > I don't understand this patch. Who would take care of doing the > bdrv_snapshot_goto on the underlying image?
loadvm needs to make bdrv_snapshot_goto. It discovers top-level replay driver and tries to perform bdrv_snapshot_goto for it. Patches 3 and 4 fix that. They allow passing through the replay driver and make saving/restoring of the actual image. Pavel Dovgalyuk > > > Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru> > > --- > > block/snapshot.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/block/snapshot.c b/block/snapshot.c > > index bf5c2ca..8998b8b 100644 > > --- a/block/snapshot.c > > +++ b/block/snapshot.c > > @@ -184,6 +184,9 @@ int bdrv_snapshot_goto(BlockDriverState *bs, > > if (!drv) { > > return -ENOMEDIUM; > > } > > + if (drv->is_filter) { > > + return 0; > > + } > > if (drv->bdrv_snapshot_goto) { > > return drv->bdrv_snapshot_goto(bs, snapshot_id); > > } > >