On Wed, Feb 13, 2013 at 02:22:09PM +0100, Kevin Wolf wrote:
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 57552aa..2819336 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -774,11 +774,33 @@ static void coroutine_fn process_l2meta(void *opaque)
> m->sleeping = false;
> }
>
> +again:
> qemu_co_mutex_lock(&s->lock);
>
> ret = qcow2_alloc_cluster_link_l2(bs, m);
> if (ret < 0) {
> - /* FIXME */
> + /*
> + * This is a nasty situation: We have already completed the
> allocation
> + * write request and returned success, so just failing it isn't
> + * possible. We need to make sure to return an error during the next
> + * flush.
> + *
> + * However, we still can't drop the l2meta because we want I/O errors
> + * to be recoverable e.g. after the block device has been grown or
> the
> + * network connection restored. Sleep until the next flush comes and
> + * then retry.
> + */
A failed flush is live migrated by hw/virtio-blk.c but what happens when
we fail during drain?
