qemu: monitor: Extract call of 'query-blockstats' and add new API for it

Allow getting the raw data from query-blockstats, so that we can use it
to detect the backing chain later on.
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_monitor.c

@@ -2241,6 +2241,21 @@ qemuMonitorGetBlockInfo(qemuMonitorPtr mon)
 }
 
 
+/**
+ * qemuMonitorQueryBlockstats:
+ * @mon: monitor object
+ *
+ * Returns data from a call to 'query-blockstats'.
+ */
+virJSONValuePtr
+qemuMonitorQueryBlockstats(qemuMonitorPtr mon)
+{
+    QEMU_CHECK_MONITOR_JSON_NULL(mon);
+
+    return qemuMonitorJSONQueryBlockstats(mon);
+}
+
+
 /**
  * qemuMonitorGetAllBlockStatsInfo:
  * @mon: monitor object

src/qemu/qemu_monitor.h

@@ -523,6 +523,8 @@ int qemuMonitorSetMemoryStatsPeriod(qemuMonitorPtr mon,
 int qemuMonitorBlockIOStatusToError(const char *status);
 virHashTablePtr qemuMonitorGetBlockInfo(qemuMonitorPtr mon);
 
+virJSONValuePtr qemuMonitorQueryBlockstats(qemuMonitorPtr mon);
+
 typedef struct _qemuBlockStats qemuBlockStats;
 typedef qemuBlockStats *qemuBlockStatsPtr;
 struct _qemuBlockStats {

src/qemu/qemu_monitor_json.c

@@ -2061,34 +2061,49 @@ qemuMonitorJSONGetOneBlockStatsInfo(virJSONValuePtr dev,
 }
 
 
-int
-qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitorPtr mon,
-                                    virHashTablePtr hash,
-                                    bool backingChain)
+virJSONValuePtr
+qemuMonitorJSONQueryBlockstats(qemuMonitorPtr mon)
 {
-    int ret = -1;
-    int nstats = 0;
-    int rc;
-    size_t i;
     virJSONValuePtr cmd;
     virJSONValuePtr reply = NULL;
-    virJSONValuePtr devices;
+    virJSONValuePtr ret = NULL;
 
     if (!(cmd = qemuMonitorJSONMakeCommand("query-blockstats", NULL)))
-        return -1;
+        return NULL;
 
-    if ((rc = qemuMonitorJSONCommand(mon, cmd, &reply)) < 0)
+    if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
         goto cleanup;
 
     if (qemuMonitorJSONCheckError(cmd, reply) < 0)
         goto cleanup;
 
-    if (!(devices = virJSONValueObjectGetArray(reply, "return"))) {
+    if (!(ret = virJSONValueObjectStealArray(reply, "return"))) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("blockstats reply was missing device list"));
+                       _("query-blockstats reply was missing device list"));
         goto cleanup;
     }
 
+ cleanup:
+    virJSONValueFree(cmd);
+    virJSONValueFree(reply);
+    return ret;
+}
+
+
+int
+qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitorPtr mon,
+                                    virHashTablePtr hash,
+                                    bool backingChain)
+{
+    int ret = -1;
+    int nstats = 0;
+    int rc;
+    size_t i;
+    virJSONValuePtr devices;
+
+    if (!(devices = qemuMonitorJSONQueryBlockstats(mon)))
+        return -1;
+
     for (i = 0; i < virJSONValueArraySize(devices); i++) {
         virJSONValuePtr dev = virJSONValueArrayGet(devices, i);
         const char *dev_name;
@@ -2120,8 +2135,7 @@ qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitorPtr mon,
     ret = nstats;
 
  cleanup:
-    virJSONValueFree(cmd);
-    virJSONValueFree(reply);
+    virJSONValueFree(devices);
     return ret;
 }
 

src/qemu/qemu_monitor_json.h

@@ -81,6 +81,8 @@ int qemuMonitorJSONSetMemoryStatsPeriod(qemuMonitorPtr mon,
                                         int period);
 int qemuMonitorJSONGetBlockInfo(qemuMonitorPtr mon,
                                 virHashTablePtr table);
+
+virJSONValuePtr qemuMonitorJSONQueryBlockstats(qemuMonitorPtr mon);
 int qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitorPtr mon,
                                         virHashTablePtr hash,
                                         bool backingChain);