Re: [PATCH v3 6/9] qemu-img: Add bitmap sub-command

[Eric Blake]

On 5/11/20 6:10 AM, Max Reitz wrote:
> On 08.05.20 20:03, Eric Blake wrote:
> > Include actions for --add, --remove, --clear, --enable, --disable, and
> > --merge (note that --clear is a bit of fluff, because the same can be
> > accomplished by removing a bitmap and then adding a new one in its
> > place, but it matches what QMP commands exist).  Listing is omitted,
> > because it does not require a bitmap name and because it was already
> > possible with 'qemu-img info'.  A single command line can play one or
> > more bitmap commands in sequence on the same bitmap name (although all
> > added bitmaps share the same granularity, and and all merged bitmaps
> > come from the same source file).  Merge defaults to other bitmaps in
> > the primary image, but can also be told to merge bitmaps from a
> > distinct image.
>
> For the record: Yes, my comment was mostly about my confusion around the
> {}.  So just replacing them by () would have pacified me.
>
> But this is more fun, of course.

> > +++ b/docs/tools/qemu-img.rst
> > @@ -281,6 +281,29 @@ Command description:
>
> [...]
>
> > +  Additional options ``-g`` set a non-default *GRANULARITY* for
>
> sets?

Or maybe:

Additional options include ``-g`` which sets a non-default *GRANULARITY* 
for ``--add``, and ``-b`` and ``-F`` which select an alternative source 
file for all *SOURCE* bitmaps used by ``--merge``.

And in writing this, I just realized - even though you _can_ use --add 
more than once in a command line, the command is still limited to 
operating on a single bitmap name, so unless you write contortions like:

qemu-img bitmap --add --remove --add -g 1024 file.qcow2 bitmapname

there will normally be at most one --add operation for a -g to be used 
with (because otherwise the second --add will fail when attempting to 
create an already-existing bitmap name).

> With that fixed (or maybe not, you know that better than me):
>
> Reviewed-by: Max Reitz <address@hidden>


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