Re: [Qemu-devel] [PATCH v3 2/2] qapi: Change BlockDirtyInfo to list

[Wenchao Xia]

于 2013/11/13 22:40, Fam Zheng 写道:
> On Wed, Nov 13, 2013 at 10:19 PM, Kevin Wolf <address@hidden> wrote:
> > Am 13.11.2013 um 11:29 hat Fam Zheng geschrieben:
> > > We have multiple dirty bitmaps in BDS now, switch QAPI to allow query
> > > it (BlockInfo.dirty_bitmaps), and also drop old BlockInfo.dirty.
> > >
> > > Signed-off-by: Fam Zheng <address@hidden>
> >
> > > diff --git a/qapi-schema.json b/qapi-schema.json
> > > index 81a375b..931d710 100644
> > > --- a/qapi-schema.json
> > > +++ b/qapi-schema.json
> > > @@ -948,8 +948,8 @@
> > >   # @tray_open: #optional True if the device has a tray and it is open
> > >   #             (only present if removable is true)
> > >   #
> > > -# @dirty: #optional dirty bitmap information (only present if the dirty
> > > -#         bitmap is enabled)
> > > +# @dirty-bitmaps: #optional dirty bitmaps information (only present if the
> > > +#                 driver has one or more dirty bitmaps)
> > >   #
> > >   # @io-status: #optional @BlockDeviceIoStatus. Only present if the device
> > >   #             supports it and the VM is configured to stop on errors
> > > @@ -963,7 +963,7 @@
> > >     'data': {'device': 'str', 'type': 'str', 'removable': 'bool',
> > >              'locked': 'bool', '*inserted': 'BlockDeviceInfo',
> > >              '*tray_open': 'bool', '*io-status': 'BlockDeviceIoStatus',
> > > -           '*dirty': 'BlockDirtyInfo' } }
> > > +           '*dirty-bitmaps': ['BlockDirtyInfo'] } }
> > >
> > >   ##
> > >   # @query-block:
> >
> > I believe this is of limited use; if you ever have more than one dirty
> > bitmap, we're lacking information to associate it with the job it
> > belongs to. One option would be to extend BlockDirtyInfo to indicate
> > this, but another might be to actually extend other commands like
> > query-block-jobs to return information on the dirty bitmap associated
> > with a specific job.
> >
> > I've applied it to block-next anyway, we still have some time to
> > reconsider for 1.8.
>
> Another case for this may be user enabled external dirty bitmap, which
> could be standalone from any block job. E.g. when we introduce a QMP
> command like:
>
> block-new-dirty-bitmap device=foo file=bar.bitmap
>
> This could be some code in block.c, could be a block job (really
> necessary?), or a block filter. I'm not sure...
>
> Fam
  This command is for sure useful, but not quite a core block fuction,
so hope it would not be in block.c. I think there is another problem
need to solve: how to let user read "bar.bitmap", three options here:
qemu-img dump, a new qmp command, a library. It seems a library is
better(probably qmp interface is also needed).