Re: [Qemu-devel] [PATCH 5/6] Add blkmirror block driver

[Eric Blake]

On 02/29/2012 06:37 AM, Paolo Bonzini wrote:
> From: Marcelo Tosatti <address@hidden>
> 
> Mirrored writes are used by live block copy.
> 
> The blkmirror driver is for internal use only, because it requires
> bdrv_append to set up a backing_hd for it.  It relies on a quirk
> of bdrv_append, which leaves the old image open for writes.
> 
> The source is hardcoded as the backing_hd for the destination, so that
> copy-on-write functions properly.  Since the source is not yet available
> at the time blkmirror_open is called, the backing_hd is set later.
> 

> +++ b/block/blkmirror.c
> @@ -0,0 +1,153 @@
> +/*
> + * Block driver for mirrored writes.
> + *
> + * Copyright (C) 2011 Red Hat, Inc.

It's now 2012; should this be expanded?

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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