cephfs admin: add support for running MON commands

Some of the queries we need to make are not mgr commands but (still?)
mon commands. Extend the interface and helper funcs to support issuing
mon commands.

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

cephfs/admin/fsadmin.go

@@ -14,6 +14,7 @@ import (
 // allow the cephfs administrative functions to interact with the Ceph cluster.
 type RadosCommander interface {
 	MgrCommand(buf [][]byte) ([]byte, string, error)
+	MonCommand(buf []byte) ([]byte, string, error)
 }
 
 // FSAdmin is used to administrate CephFS within a ceph cluster.
@@ -76,6 +77,25 @@ func (fsa *FSAdmin) marshalMgrCommand(v interface{}) ([]byte, string, error) {
 	return fsa.rawMgrCommand(b)
 }
 
+// rawMonCommand takes a byte buffer and sends it to the MON as a command.
+// The buffer is expected to contain preformatted JSON.
+func (fsa *FSAdmin) rawMonCommand(buf []byte) ([]byte, string, error) {
+	if err := fsa.validate(); err != nil {
+		return nil, "", err
+	}
+	return fsa.conn.MonCommand(buf)
+}
+
+// marshalMonCommand takes an generic interface{} value, converts it to JSON and
+// sends the json to the MGR as a command.
+func (fsa *FSAdmin) marshalMonCommand(v interface{}) ([]byte, string, error) {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return nil, "", err
+	}
+	return fsa.rawMonCommand(b)
+}
+
 type listNamedResult struct {
 	Name string `json:"name"`
 }

cephfs/admin/fsadmin_test.go

@@ -42,6 +42,7 @@ func tracer(c RadosCommander) RadosCommander {
 }
 
 func (t *tracingCommander) MgrCommand(buf [][]byte) ([]byte, string, error) {
+	fmt.Println("(MGR Command)")
 	for i := range buf {
 		fmt.Println("IN:", string(buf[i]))
 	}
@@ -56,6 +57,20 @@ func (t *tracingCommander) MgrCommand(buf [][]byte) ([]byte, string, error) {
 	return r, s, err
 }
 
+func (t *tracingCommander) MonCommand(buf []byte) ([]byte, string, error) {
+	fmt.Println("(MON Command)")
+	fmt.Println("IN:", string(buf))
+	r, s, err := t.conn.MonCommand(buf)
+	fmt.Println("OUT(result):", string(r))
+	if s != "" {
+		fmt.Println("OUT(status):", s)
+	}
+	if err != nil {
+		fmt.Println("OUT(error):", err.Error())
+	}
+	return r, s, err
+}
+
 func getFSAdmin(t *testing.T) *FSAdmin {
 	if cachedFSAdmin != nil {
 		return cachedFSAdmin