cephfs: allow creating mount with an id

The ceph api function supports passing a string to identify the
client doing the mount. Expose that aspect of the api with a
new function CreateMountWithId.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

cephfs/cephfs.go

@@ -38,16 +38,28 @@ type MountInfo struct {
 	mount *C.struct_ceph_mount_info
 }
 
-// CreateMount creates a mount handle for interacting with Ceph.
-func CreateMount() (*MountInfo, error) {
+func createMount(id *C.char) (*MountInfo, error) {
 	mount := &MountInfo{}
-	ret := C.ceph_create(&mount.mount, nil)
+	ret := C.ceph_create(&mount.mount, id)
 	if ret != 0 {
 		return nil, getError(ret)
 	}
 	return mount, nil
 }
 
+// CreateMount creates a mount handle for interacting with Ceph.
+func CreateMount() (*MountInfo, error) {
+	return createMount(nil)
+}
+
+// CreateMountWithId creates a mount handle for interacting with Ceph.
+// The caller can specify a unique id that will identify this client.
+func CreateMountWithId(id string) (*MountInfo, error) {
+	cid := C.CString(id)
+	defer C.free(unsafe.Pointer(cid))
+	return createMount(cid)
+}
+
 // CreateFromRados creates a mount handle using an existing rados cluster
 // connection.
 //

cephfs/cephfs_test.go

@@ -221,3 +221,18 @@ func TestCreateFromRados(t *testing.T) {
 	assert.NoError(t, err)
 	assert.NotNil(t, mount)
 }
+
+func TestCreateMountWithId(t *testing.T) {
+	// TODO: the entity_id is visible w/in the 'session ls' output
+	// of mds. Consider running the equivalent api call and checking
+	// that the string is set.
+	mount, err := CreateMountWithId("bob")
+	assert.NoError(t, err)
+	assert.NotNil(t, mount)
+
+	err = mount.ReadDefaultConfigFile()
+	assert.NoError(t, err)
+
+	err = mount.Mount()
+	assert.NoError(t, err)
+}