test: use librados API to retrieve config params

The CephContext object is not ABI-stable, so it is necessary to
use the "conf_get" librados methods to safely retrieve a setting.

Fixes: http://tracker.ceph.com/issues/18617
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit 2ed02f3)

Conflicts:
	src/test/librbd/test_librbd.cc (jewel does not have
            006138e or
            cb3712e)

src/test/librbd/test_librbd.cc

@@ -179,6 +179,12 @@ class TestLibRBD : public ::testing::Test {
     ASSERT_NE("", m_pool_name = create_pool());
   }
 
+  bool is_skip_partial_discard_enabled() {
+    std::string value;
+    EXPECT_EQ(0, _rados.conf_get("rbd_skip_partial_discard", value));
+    return value == "true";
+  }
+
   void validate_object_map(rbd_image_t image, bool *passed) {
     uint64_t flags;
     ASSERT_EQ(0, rbd_get_flags(image, &flags));
@@ -1250,8 +1256,7 @@ TEST_F(TestLibRBD, TestIO)
   rados_ioctx_t ioctx;
   rados_ioctx_create(_cluster, m_pool_name.c_str(), &ioctx);
 
-  CephContext* cct = reinterpret_cast<CephContext*>(_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = is_skip_partial_discard_enabled();
 
   rbd_image_t image;
   int order = 0;
@@ -1329,8 +1334,7 @@ TEST_F(TestLibRBD, TestIOWithIOHint)
   rados_ioctx_t ioctx;
   rados_ioctx_create(_cluster, m_pool_name.c_str(), &ioctx);
 
-  CephContext* cct = reinterpret_cast<CephContext*>(_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = is_skip_partial_discard_enabled();
 
   rbd_image_t image;
   int order = 0;
@@ -1543,8 +1547,7 @@ TEST_F(TestLibRBD, TestIOPP)
   librados::IoCtx ioctx;
   ASSERT_EQ(0, _rados.ioctx_create(m_pool_name.c_str(), ioctx));
 
-  CephContext* cct = reinterpret_cast<CephContext*>(_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = is_skip_partial_discard_enabled();
 
   {
     librbd::RBD rbd;
@@ -2578,8 +2581,7 @@ TYPED_TEST(DiffIterateTest, DiffIterate)
   librados::IoCtx ioctx;
   ASSERT_EQ(0, this->_rados.ioctx_create(this->m_pool_name.c_str(), ioctx));
 
-  CephContext* cct = reinterpret_cast<CephContext*>(this->_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = this->is_skip_partial_discard_enabled();
 
   {
     librbd::RBD rbd;
@@ -2729,8 +2731,7 @@ TYPED_TEST(DiffIterateTest, DiffIterateStress)
   librados::IoCtx ioctx;
   ASSERT_EQ(0, this->_rados.ioctx_create(this->m_pool_name.c_str(), ioctx));
 
-  CephContext* cct = reinterpret_cast<CephContext*>(this->_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = this->is_skip_partial_discard_enabled();
 
   librbd::RBD rbd;
   librbd::Image image;
@@ -2851,8 +2852,7 @@ TYPED_TEST(DiffIterateTest, DiffIterateIgnoreParent)
   librados::IoCtx ioctx;
   ASSERT_EQ(0, this->_rados.ioctx_create(this->m_pool_name.c_str(), ioctx));
 
-  CephContext* cct = reinterpret_cast<CephContext*>(this->_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = this->is_skip_partial_discard_enabled();
 
   librbd::RBD rbd;
   librbd::Image image;
@@ -2903,8 +2903,7 @@ TYPED_TEST(DiffIterateTest, DiffIterateCallbackError)
   librados::IoCtx ioctx;
   ASSERT_EQ(0, this->_rados.ioctx_create(this->m_pool_name.c_str(), ioctx));
 
-  CephContext* cct = reinterpret_cast<CephContext*>(this->_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = this->is_skip_partial_discard_enabled();
 
   {
     librbd::RBD rbd;
@@ -2936,8 +2935,7 @@ TYPED_TEST(DiffIterateTest, DiffIterateParentDiscard)
   librados::IoCtx ioctx;
   ASSERT_EQ(0, this->_rados.ioctx_create(this->m_pool_name.c_str(), ioctx));
 
-  CephContext* cct = reinterpret_cast<CephContext*>(this->_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = this->is_skip_partial_discard_enabled();
 
   librbd::RBD rbd;
   librbd::Image image;
@@ -3893,8 +3891,7 @@ TEST_F(TestLibRBD, BlockingAIO)
   librados::IoCtx ioctx;
   ASSERT_EQ(0, _rados.ioctx_create(m_pool_name.c_str(), ioctx));
 
-  CephContext* cct = reinterpret_cast<CephContext*>(_rados.cct());
-  bool skip_discard = cct->_conf->rbd_skip_partial_discard;
+  bool skip_discard = is_skip_partial_discard_enabled();
 
   librbd::RBD rbd;
   std::string name = get_temp_image_name();
@@ -4449,8 +4446,7 @@ TEST_F(TestLibRBD, FlushCacheWithCopyupOnExternalSnapshot) {
 
 TEST_F(TestLibRBD, DiscardAfterWrite)
 {
-  CephContext* cct = reinterpret_cast<CephContext*>(_rados.cct());
-  REQUIRE(!cct->_conf->rbd_skip_partial_discard);
+  REQUIRE(!is_skip_partial_discard_enabled());
 
   librados::IoCtx ioctx;
   ASSERT_EQ(0, _rados.ioctx_create(m_pool_name.c_str(), ioctx));