Re: [Qemu-devel] [PATCH 1/3] block: add resize monitor command

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, Jan 14, 2011 at 4:20 PM, Christoph Hellwig <hch@lst.de> wrote:
> +STEXI
> +@item resize
> +@findex resize
> +Resize a block image while a guest is running.  Usuaully requires guest

s/Usuaully/Usually/

> +action to see the updated size.  Resize to a lower size is supported,
> +but should be used with extreme caution.

This resizes the image files.  Resizing an LVM volume is a useful case
too.  One way to integrate that feature is to implement a host_device
.bdrv_truncate() that checks the underlying device size and returns
success if it matches the new value and failure otherwise.  Or perhaps
allow the QEMU resize command without an argument to fetch the size
from the underlying device (aka refresh the size).

> +    if (bdrv_get_type_hint(bs) == BDRV_TYPE_CDROM) {
> +        error_report("Can not resize CDROM devices\n");
> +        return -1;
> +    }

Hrm...BDRV_TYPE_FLOPPY probably too?

Stefan