A missing space makes for poor error messages, and sizes can't go negative. Also, we missed diagnosing a server that sends a maximum block size less than the minimum. Fixes:081dd1feCC: qemu-stable@nongnu.org Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20180501154654.943782-1-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> (cherry picked from commite475d108f1) Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>