vvfat: do not fail if the disk has spare sectors If the number of "faked sectors" + the number of sectors that are part of a cluster does not sum up to the total number of sectors, qemu-img convert fails. Read these spare sectors as all zeros. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>