On 06/07/2017 08:55 AM, Jeff Cody wrote: > In external_snapshot_abort(), we try to undo what was done in > external_snapshot_prepare() calling bdrv_replace_node() to swap the > nodes back. However, we receive a permissions error as writers are > blocked on the old node, which is now the new node backing file. > > An easy fix (initially suggested by Kevin Wolf) is to call > bdrv_set_backing_hd() on the new node, to set the backing node to NULL. > > Signed-off-by: Jeff Cody <jc...@redhat.com> > --- > blockdev.c | 4 ++++ > 1 file changed, 4 insertions(+) >
Reviewed-by: Eric Blake <ebl...@redhat.com>
> diff --git a/blockdev.c b/blockdev.c
> index 892d768..6472548 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1803,7 +1803,11 @@ static void external_snapshot_abort(BlkActionState
> *common)
> DO_UPCAST(ExternalSnapshotState, common,
> common);
> if (state->new_bs) {
> if (state->overlay_appended) {
> + bdrv_ref(state->old_bs); /* we can't let bdrv_set_backind_hd()
> + close state->old_bs; we need it */
> + bdrv_set_backing_hd(state->new_bs, NULL, &error_abort);
> bdrv_replace_node(state->new_bs, state->old_bs, &error_abort);
> + bdrv_unref(state->old_bs); /* bdrv_replace_node() ref'ed old_bs
> */
> }
> }
> }
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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