On 11/14/2014 06:06 AM, Max Reitz wrote: > Add a refcount_order parameter to qcow2_create2(), use that value for > the image header and for calculating the size required for > preallocation. > > For now, always pass 4. > > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > block/qcow2.c | 41 ++++++++++++++++++++++++++++++----------- > 1 file changed, 30 insertions(+), 11 deletions(-) >
> @@ -1811,6 +1811,13 @@ static int qcow2_create2(const char *filename, int64_t > total_size, > int64_t meta_size = 0; > uint64_t nreftablee, nrefblocke, nl1e, nl2e; > int64_t aligned_total_size = align_offset(total_size, cluster_size); > + int refblock_bits, refblock_size; > + /* refcount entry size in bytes */ > + double rces = (1 << refcount_order) / 8.; > + Maybe worth a comment that absolute precision is not necessary, and that we are okay that the result gets us to within a fraction of a percent of the right value. Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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