Re: [Qemu-devel] [PATCH 1/4] block/parallels: extend parallels format header with actual data values

[Denis V. Lunev]

On 24/07/14 22:34, Jeff Cody wrote:
> On Tue, Jul 22, 2014 at 05:19:34PM +0400, Denis V. Lunev wrote:
> > Parallels image format has several additional fields inside:
> > - nb_sectors is actually 64 bit wide. Upper 32bits are not used for
> >    images with signature "WithoutFreeSpace" and must be explicitely
> s/explicitely/explicitly
>
> >    zeroed according to Parallels. They will be used for images with
> >    signature "WithouFreSpacExt"
> > - inuse is magic which means that the image is currently opened for
> >    read/write or was not closed correctly, the magic is 0x746f6e59
> > - data_off is the location of the first data block. It can be zero
> >    and in this case
> I think you may have forgotten to finish this sentence :)
ok
> > This patch adds these values to struct parallels_header and adds
> > proper handling of nb_sectors for currently supported WithoutFreeSpace
> > images.
> >
> > WithouFreSpacExt will be covered in the next patch.
> >
> > Signed-off-by: Denis V. Lunev <address@hidden>
> > CC: Kevin Wolf <address@hidden>
> > CC: Stefan Hajnoczi <address@hidden>
> > ---
> >   block/parallels.c | 8 +++++---
> >   1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/block/parallels.c b/block/parallels.c
> > index 1a5bd35..c44df87 100644
> > --- a/block/parallels.c
> > +++ b/block/parallels.c
> > @@ -41,8 +41,10 @@ struct parallels_header {
> >       uint32_t cylinders;
> >       uint32_t tracks;
> >       uint32_t catalog_entries;
> > -    uint32_t nb_sectors;
> > -    char padding[24];
> > +    uint64_t nb_sectors;
> > +    uint32_t inuse;
> > +    uint32_t data_off;
> > +    char padding[12];
> >   } QEMU_PACKED;
> >   
> >   typedef struct BDRVParallelsState {
> > @@ -90,7 +92,7 @@ static int parallels_open(BlockDriverState *bs, QDict 
> > *options, int flags,
> >           goto fail;
> >       }
> >   
> > -    bs->total_sectors = le32_to_cpu(ph.nb_sectors);
> > +    bs->total_sectors = (uint32_t)le64_to_cpu(ph.nb_sectors);
> I think an explicit bit mask on the upper 32 bits would fit better
> here than a cast, especially since neither 'bs->total_sectors' nor
> 'ph.nb_sectors' is a uint32_t. E.g.:
>
>      bs->total_sectors = 0xffffffff & le64_to_cpu(ph.nb_sectors);
ok, will do