Re: [Qemu-devel] [PATCH v1 0/6] Report format specific info for LUKS block driver

[Daniel P. Berrange]

On Tue, Jun 14, 2016 at 03:56:30PM +0200, Max Reitz wrote:
> On 07.06.2016 12:11, Daniel P. Berrange wrote:
> > The 'qemu-img info' tool has ability to print format specific
> > information, eg with qcow2 it reports two extra items:
> > 
> >   $ qemu-img info ~/VirtualMachines/demo.qcow2
> >   image: /home/berrange/VirtualMachines/demo.qcow2
> >   file format: qcow2
> >   virtual size: 3.0G (3221225472 bytes)
> >   disk size: 140K
> >   cluster_size: 65536
> >   Format specific information:
> >       compat: 0.10
> >       refcount bits: 16
> > 
> > 
> > This is not currently wired up for the LUKS driver. This patch
> > series adds that support so that we can report useful data about
> > the LUKS volume such as the crypto algorithm choices, key slot
> > usage and other volume metadata.
> > 
> > The first patch extends the crypto API to allow querying of the
> > format specific metadata
> > 
> > The second patches extends the block API to allow the LUKS driver
> > to report the format specific metadata.
> > 
> >     $ qemu-img info ~/VirtualMachines/demo.luks
> >     image: /home/berrange/VirtualMachines/demo.luks
> >     file format: luks
> >     virtual size: 98M (102760448 bytes)
> >     disk size: 100M
> >     encrypted: yes
> >     Format specific information:
> >         cipher-alg: aes-128
> >         cipher-mode: xts
> >         ivgen-alg: plain64
> >         hash-alg: sha1
> >         payload-offset: 2097152
> >         master-key-iters: 142375
> >         uuid: 6ddee74b-3a22-408c-8909-6789d4fa2594
> >         slots:
> >             [0]:
> >                 active: true
> >                 iters: 572706
> >                 stripes: 4000
> >                 key-offset: 8
> >             [1]:
> >                 active: false
> >                 iters: 0
> >                 stripes: 4000
> >                 key-offset: 264
> >             [2]:
> >                 active: false
> >                 iters: 0
> >                 stripes: 4000
> >                 key-offset: 520
> >             [3]:
> >                 active: false
> >                 iters: 0
> >                 stripes: 4000
> >                 key-offset: 776
> >             [4]:
> >                 active: false
> >                 iters: 0
> >                 stripes: 4000
> >                 key-offset: 1032
> >             [5]:
> >                 active: false
> >                 iters: 0
> >                 stripes: 4000
> >                 key-offset: 1288
> >             [6]:
> >                 active: false
> >                 iters: 0
> >                 stripes: 4000
> >                 key-offset: 1544
> >             [7]:
> >                 active: false
> >                 iters: 0
> >                 stripes: 4000
> >                 key-offset: 1800
> > 
> > The remaining 4 patches are improvements to QAPI and the core
> > block layer to fix a problem whereby struct fields are output
> > in (apparently) random ordering. This is because the QAPI type
> > is converted into a QObject for pretty-printing, thus throwing
> > away any struct field ordering information.
> > 
> > To address this I created a new TextOutputVisitor which can
> > directly pretty-print QAPI types. I then changed the code
> > generator to create qapi_stringify_TYPENAME() methods for
> > all QAPI types. Finally I changed the block layer over to
> > use this stringify approach instead.
> 
> General nagging: This new approach no longer replaces dashes with spaces
> in the key names. Is it worth doing something about this?

Opps, didn't notice that. Should be pretty easy to deal with that
in the visitor.

Regards,
Daniel
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