mon/OSDMonitor: fix improper input/testing range of crush somke testing

CrushTester::test() will reset testing range to [0, 1023] whenever
min_x or max_x is negative and the constructor of CrushTester will
always default min_x and max_x to -1.

Thus to set the test range correctly, you have to specify both min_x and max_x.
Local test shows this patch shall decrease the time consumed by the crush
smoke testing to approximate 1/20 of those without this.

For exmaple:
crush somke test duration: 0.668354 seconds ->
crush somke test duration: 0.012592 seconds

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>

src/mon/OSDMonitor.cc

@@ -5800,15 +5800,20 @@ int OSDMonitor::prepare_new_pool(string& name, uint64_t auid,
     _get_pending_crush(newcrush);
     ostringstream err;
     CrushTester tester(newcrush, err);
+    tester.set_min_x(0);
     tester.set_max_x(50);
     tester.set_rule(crush_rule);
+    auto start = ceph_clock_now();
     r = tester.test_with_fork(g_conf->mon_lease);
+    auto duration = ceph_clock_now() - start;
     if (r < 0) {
       dout(10) << " tester.test_with_fork returns " << r
 	       << ": " << err.str() << dendl;
       *ss << "crush test failed with " << r << ": " << err.str();
       return r;
     }
+    dout(10) << __func__ << " crush somke test duration: "
+             << duration << " seconds" << dendl;
   }
   unsigned size, min_size;
   r = prepare_pool_size(pool_type, erasure_code_profile, &size, &min_size, ss);
@@ -7375,16 +7380,20 @@ bool OSDMonitor::prepare_command_impl(MonOpRequestRef op,
       dout(10) << " testing map" << dendl;
       stringstream ess;
       CrushTester tester(crush, ess);
+      tester.set_min_x(0);
       tester.set_max_x(50);
+      auto start = ceph_clock_now();
       int r = tester.test_with_fork(g_conf->mon_lease);
+      auto duration = ceph_clock_now() - start;
       if (r < 0) {
 	dout(10) << " tester.test_with_fork returns " << r
 		 << ": " << ess.str() << dendl;
 	ss << "crush smoke test failed with " << r << ": " << ess.str();
 	err = r;
 	goto reply;
       }
-      dout(10) << " crush test result " << ess.str() << dendl;
+      dout(10) << __func__ << " crush somke test duration: "
+               << duration << " seconds" << dendl;
     }
 
     pending_inc.crush = data;