Re: [Qemu-devel] [PATCH V3 2/7] qemu-nbd: support internal snapshot export

[Eric Blake <eblake@redhat.com>]

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On 09/25/2013 06:16 PM, Wenchao Xia wrote:
> Now it is possible to directly export an internal snapshot, which
> can be used to probe the snapshot's contents without qemu-img
> convert.
> 
> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
> ---
>  block/snapshot.c         |   18 ++++++++++++++++++
>  include/block/snapshot.h |    6 ++++++
>  qemu-nbd.c               |   35 ++++++++++++++++++++++++++++++++++-
>  3 files changed, 58 insertions(+), 1 deletions(-)

Woo-hoo!  Long desired.  It would be even cooler if we could set up the
export directly from a running qemu instance, rather than having to
spawn an external qemu-nbd process (after all, we've already documented
that having more than one process directly using the same qcow2 file is
not safe), but this is a step in the right direction.

> @@ -328,6 +331,8 @@ int main(int argc, char **argv)
>          { "connect", 1, NULL, 'c' },
>          { "disconnect", 0, NULL, 'd' },
>          { "snapshot", 0, NULL, 's' },
> +        { "load-snapshot", 1, NULL, 'l' },
> +        { "load-snapshot1", 1, NULL, 'L' },

Uggh.  This makes getopt_long's unambiguous-prefix handling very hard to
use.  For example, --dis is recognized as short for --disconnect; but
here --load is NOT short for --load-snapshot, because it could also be
short for --load-snapshot1.  And why the 1 suffix?  Can you come up with
a better name that distinguishes why you have to have two different long
options, and which doesn't overlap on as much of a common prefix?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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