[PATCH for 7.10] qemu: monitor: Fix usage of 'query-blockstats'

[Peter Krempa]

Commit bc24810c2cab modified code querying blockstats to use the
'query-nodes' parameter so that we can fetch stats also for images which
are not attached to a frontend such as block copy and backup scratch
images.

Unfortunately that broke the old blockstats because if 'query-nodes' is
enabled qemu doesn't output the 'qdev' parameter which our code used for
matching to the disk and also qemu neglects to populate the frontend
stats at all so we can't even switch to using nodenema for matching.

To fix this we need to do two calls, one with 'query-nodes' disabled
using the old logic to populate everything and then an aditional one
which populates all the remaining images.

Closes: https://gitlab.com/libvirt/libvirt/-/issues/246
Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
 src/qemu/qemu_monitor_json.c | 52 +++++++++++++++++++++++++++++++++---
 tests/qemumonitorjsontest.c  |  2 ++
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 3030cff664..56f0b22b2a 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -2446,6 +2446,30 @@ qemuMonitorJSONGetOneBlockStatsInfo(virJSONValue *dev,
 }


+static int
+qemuMonitorJSONGetOneBlockStatsNodeInfo(virJSONValue *dev,
+                                        GHashTable *hash)
+{
+    qemuBlockStats *bstats = NULL;
+    int nstats = 0;
+    const char *nodename = NULL;
+
+    if (!(nodename = virJSONValueObjectGetString(dev, "node-name")))
+        return 0;
+
+    /* we already have the stats */
+    if (g_hash_table_contains(hash, nodename))
+        return 0;
+
+    if (!(bstats = qemuMonitorJSONBlockStatsCollectData(dev, &nstats)))
+        return -1;
+
+    g_hash_table_insert(hash, g_strdup(nodename), bstats);
+
+    return nstats;
+}
+
+
 virJSONValue *
 qemuMonitorJSONQueryBlockstats(qemuMonitor *mon,
                                bool queryNodes)
@@ -2475,13 +2499,14 @@ qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitor *mon,
     int nstats = 0;
     int rc;
     size_t i;
-    g_autoptr(virJSONValue) devices = NULL;
+    g_autoptr(virJSONValue) blockstatsDevices = NULL;
+    g_autoptr(virJSONValue) blockstatsNodes = NULL;

-    if (!(devices = qemuMonitorJSONQueryBlockstats(mon, true)))
+    if (!(blockstatsDevices = qemuMonitorJSONQueryBlockstats(mon, false)))
         return -1;

-    for (i = 0; i < virJSONValueArraySize(devices); i++) {
-        virJSONValue *dev = virJSONValueArrayGet(devices, i);
+    for (i = 0; i < virJSONValueArraySize(blockstatsDevices); i++) {
+        virJSONValue *dev = virJSONValueArrayGet(blockstatsDevices, i);
         const char *dev_name;

         if (!dev || virJSONValueGetType(dev) != VIR_JSON_TYPE_OBJECT) {
@@ -2505,6 +2530,25 @@ qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitor *mon,
             nstats = rc;
     }

+    if (!(blockstatsNodes = qemuMonitorJSONQueryBlockstats(mon, true)))
+        return -1;
+
+    for (i = 0; i < virJSONValueArraySize(blockstatsNodes); i++) {
+        virJSONValue *dev = virJSONValueArrayGet(blockstatsNodes, i);
+
+        if (!dev || virJSONValueGetType(dev) != VIR_JSON_TYPE_OBJECT) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("blockstats device entry was not in expected format"));
+            return -1;
+        }
+
+        if ((rc = qemuMonitorJSONGetOneBlockStatsNodeInfo(dev, hash)) < 0)
+            return -1;
+
+        if (rc > nstats)
+            nstats = rc;
+    }
+
     return nstats;
 }

diff --git a/tests/qemumonitorjsontest.c b/tests/qemumonitorjsontest.c
index 0de523007b..bcf5caa9a4 100644
--- a/tests/qemumonitorjsontest.c
+++ b/tests/qemumonitorjsontest.c
@@ -1615,6 +1615,8 @@ testQemuMonitorJSONqemuMonitorJSONGetAllBlockStatsInfo(const void *opaque)

     if (qemuMonitorTestAddItem(test, "query-blockstats", reply) < 0)
         return -1;
+    if (qemuMonitorTestAddItem(test, "query-blockstats", reply) < 0)
+        return -1;

 #define CHECK0FULL(var, value, varformat, valformat) \
     if (stats->var != value) { \
-- 
2.31.1