Re: [Qemu-devel] [PATCH 5/5] qemu-nbd: Add --bitmap=NAME option

[Eric Blake <eblake@redhat.com>]

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On 1/8/19 10:14 PM, Eric Blake wrote:
> Having to fire up qemu, then use QMP commands for nbd-server-start
> and nbd-server-add, just to expose a persistent dirty bitmap, is
> rather tedious.  Make it possible to expose a dirty bitmap using
> just qemu-nbd (of course, for now this only works when qemu-nbd is
> visiting a BDS formatted as qcow2).
> 
> For now, I play it safe and only allow a bitmap to be exposed on
> a read-only image.  We may relax it in the future.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  qemu-nbd.texi |  5 +++++
>  qemu-nbd.c    | 16 ++++++++++++++--
>  2 files changed, 19 insertions(+), 2 deletions(-)
> 

> @@ -1015,7 +1027,7 @@ int main(int argc, char **argv)
>          }
>      }
> 
> -    exp = nbd_export_new(bs, dev_offset, fd_size, export_name, NULL, NULL,
> +    exp = nbd_export_new(bs, dev_offset, fd_size, export_name, bitmap, NULL,
>                           export_description, nbdflags, nbd_export_closed,
>                           writethrough, NULL, &error_fatal);

The cover letter DID warn that this was only lightly tested.  For it to
even work, you have to s/bitmap, NULL/NULL, bitmap/ or else swap the
meaning of the --bitmap and --description command line options.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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