Re: [Qemu-devel] [PATCH v3 00/12] block/json: Add JSON protocol driver

[Max Reitz]

On 06.05.2014 10:10, Stefan Hajnoczi wrote:
> On Mon, May 05, 2014 at 06:19:07PM +0200, Max Reitz wrote:
> > On 10.04.2014 20:43, Max Reitz wrote:
> > > This series adds a passthrough JSON protocol block driver. Its filenames
> > > are JSON objects prefixed by "json:". The objects are used as options
> > > for opening another block device which will be the child of the JSON
> > > device. Regarding this child device, the JSON driver behaves nearly the
> > > same as raw_bsd in that it is just a passthrough driver. The only
> > > difference is probably that the JSON driver identifies itself as a block
> > > filter, in contrast to raw_bsd.
> > >
> > > The purpose of this driver is that it may sometimes be desirable to
> > > specify options for a block device where only a filename can be given,
> > > e.g., for backing files. Using this should obviously be the exception,
> > > but it is nice to have if actually needed.
> > Ping – I do understand that Kevin has reservations against this
> > series, but as long as he doesn't explicitly ask me to reimplement
> > this in bdrv_open() without an own block driver (which I'd more or
> > less gladly do), I do not see issues why this series should not be
> > merged.
> I haven't reviewed it further because it seems like a kludge (that we
> have to keep supporting once it's merged).  Was hoping you and Kevin
> will come up with a long-term fix instead.

Okay, if you think the same, I guess I'll have to rewrite this series. I 
agree that including this functionality in bdrv_open() is the nicer 
alternative from the user's point of view, whereas I think using a 
separate block driver results in nicer code.

I'll rewrite this series and then we'll see how bad it actually looks. ;-)

Max