Re: [Qemu-devel] [PATCH v3 2/2] qemu: use bdrv_flush_all for vm_stop et al

[John Snow <jsnow@redhat.com>]

On 09/15/2016 07:42 PM, John Snow wrote:
> Bypass the usual check to see if we are "allowed" to flush via the
> block model, and manually flush the BDS nodes themselves instead.
>
> This allows us to do things like migrate when we have a device with
> an open tray, but has a node that may need to be flushed.
>
> Specifically, this allows us to migrate when we have a CDROM with
> an open tray.
>

How about:

Reimplement bdrv_flush_all for vm_stop. In contrast to blk_flush_all,
bdrv_flush_all does not have device model restrictions. This allows
us to flush and halt unconditionally without error.

This allows us to do things like migrate when we have a device with
an open tray, but has a node that may need to be flushed.

Specifically, this allows us to migrate when we have a CDROM with
an open tray.

> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  cpus.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/cpus.c b/cpus.c
> index e39ccb7..96d9352 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -751,7 +751,7 @@ static int do_vm_stop(RunState state)
>      }
>
>      bdrv_drain_all();
> -    ret = blk_flush_all();
> +    ret = bdrv_flush_all();
>
>      return ret;
>  }
> @@ -1494,7 +1494,7 @@ int vm_stop_force_state(RunState state)
>          bdrv_drain_all();
>          /* Make sure to return an error if the flush in a previous vm_stop()
>           * failed. */
> -        return blk_flush_all();
> +        return bdrv_flush_all();
>      }
>  }
>
>