On 05/28/2014 08:25 AM, Markus Armbruster wrote: > A call to retrieve the image size converts between bytes and sectors > several times: > > * BlockDriver method bdrv_getlength() returns bytes. > > * refresh_total_sectors() converts to sectors, rounding up, and stores > in total_sectors. > > * bdrv_getlength() converts total_sectors back to bytes (now rounded > up to a multiple of the sector size). > > * Callers wanting sectors rather bytes convert it right back. > Example: bdrv_get_geometry(). > > bdrv_nb_sectors() provides a way to omit the last two conversions. > It's exactly bdrv_getlength() with the conversion to bytes omitted. > It's functionally like bdrv_get_geometry() without its odd error > handling. > > Reimplement bdrv_getlength() and bdrv_get_geometry() on top of > bdrv_nb_sectors(). > > The next patches will convert some users of bdrv_getlength() to > bdrv_nb_sectors(). > > Signed-off-by: Markus Armbruster <arm...@redhat.com> > --- > block.c | 29 +++++++++++++++++++---------- > include/block/block.h | 1 + > 2 files changed, 20 insertions(+), 10 deletions(-)
Reviewed-by: Eric Blake <ebl...@redhat.com> > +/** > + * Return length in bytes on success, -errno on error. > + * The length is always a multiple of BDRV_SECTOR_SIZE. > + */ > +int64_t bdrv_getlength(BlockDriverState *bs) The second sentence might not always be true in the future if we add support for image length not a multiple of sector size; but we can correct it at the point we make such a change. For now, it is worth keeping. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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