qemu: bulk stats: add block allocation information

Management software wants to be able to allocate disk space on demand.
To support this they need keep track of the space occupation of the
block device.  This information is reported by qemu as part of block
stats.

This patch extend the block information in the bulk stats with the
allocation information.

To keep the same behaviour a helper is extracted from
qemuMonitorJSONGetBlockExtent in order to get per-device allocation
information.

Signed-off-by: Francesco Romani <fromani@redhat.com>
Signed-off-by: Peter Krempa <pkrempa@redhat.com>

src/libvirt.c

@@ -21656,6 +21656,12 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  *                          unsigned long long.
  * "block.<num>.errors" - Xen only: the 'oo_req' value as
  *                        unsigned long long.
+ * "block.<num>.allocation" - offset of the highest written sector
+ *                            as unsigned long long.
+ * "block.<num>.capacity" - logical size in bytes of the block device backing
+ *                          image as unsigned long long.
+ * "block.<num>.physical" - physical size in bytes of the container of the
+ *                          backing image as unsigned long long.
  *
  * Note that entire stats groups or individual stat fields may be missing from
  * the output in case they are not supported by the given hypervisor, are not

src/qemu/qemu_driver.c

@@ -17907,6 +17907,19 @@ do { \
         goto cleanup; \
 } while (0)
 
+#define QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, num, name, value) \
+do { \
+    char param_name[VIR_TYPED_PARAM_FIELD_LENGTH]; \
+    snprintf(param_name, VIR_TYPED_PARAM_FIELD_LENGTH, \
+             "block.%zu.%s", num, name); \
+    if (virTypedParamsAddULLong(&(record)->params, \
+                                &(record)->nparams, \
+                                maxparams, \
+                                param_name, \
+                                value) < 0) \
+        goto cleanup; \
+} while (0)
+
 static int
 qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
                         virDomainObjPtr dom,
@@ -17925,6 +17938,7 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
 
     qemuDomainObjEnterMonitor(driver, dom);
     rc = qemuMonitorGetAllBlockStatsInfo(priv->mon, &stats);
+    ignore_value(qemuMonitorBlockStatsUpdateCapacity(priv->mon, stats));
     qemuDomainObjExitMonitor(driver, dom);
 
     if (rc < 0) {
@@ -17961,6 +17975,17 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
                                 "fl.reqs", entry->flush_req);
         QEMU_ADD_BLOCK_PARAM_LL(record, maxparams, i,
                                 "fl.times", entry->flush_total_times);
+
+        QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, i,
+                                 "allocation", entry->wr_highest_offset);
+
+        if (entry->capacity)
+            QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, i,
+                                     "capacity", entry->capacity);
+        if (entry->physical)
+            QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, i,
+                                     "physical", entry->physical);
+
     }
 
     ret = 0;
@@ -17972,6 +17997,8 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
 
 #undef QEMU_ADD_BLOCK_PARAM_LL
 
+#undef QEMU_ADD_BLOCK_PARAM_ULL
+
 #undef QEMU_ADD_NAME_PARAM
 
 #undef QEMU_ADD_COUNT_PARAM

src/qemu/qemu_monitor.h

@@ -360,6 +360,7 @@ struct _qemuBlockStats {
     long long flush_total_times;
     unsigned long long capacity;
     unsigned long long physical;
+    unsigned long long wr_highest_offset;
 };
 
 int qemuMonitorGetAllBlockStatsInfo(qemuMonitorPtr mon,

src/qemu/qemu_monitor_json.c

@@ -1782,6 +1782,40 @@ int qemuMonitorJSONGetBlockStatsInfo(qemuMonitorPtr mon,
 }
 
 
+typedef enum {
+    QEMU_MONITOR_BLOCK_EXTENT_ERROR_OK,
+    QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOPARENT,
+    QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOSTATS,
+    QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOOFFSET,
+} qemuMonitorBlockExtentError;
+
+
+static int
+qemuMonitorJSONDevGetBlockExtent(virJSONValuePtr dev,
+                                 unsigned long long *extent)
+{
+    virJSONValuePtr stats;
+    virJSONValuePtr parent;
+
+    if ((parent = virJSONValueObjectGet(dev, "parent")) == NULL ||
+        parent->type != VIR_JSON_TYPE_OBJECT) {
+        return QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOPARENT;
+    }
+
+    if ((stats = virJSONValueObjectGet(parent, "stats")) == NULL ||
+        stats->type != VIR_JSON_TYPE_OBJECT) {
+        return QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOSTATS;
+    }
+
+    if (virJSONValueObjectGetNumberUlong(stats, "wr_highest_offset",
+                                         extent) < 0) {
+        return QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOOFFSET;
+    }
+
+    return QEMU_MONITOR_BLOCK_EXTENT_ERROR_OK;
+}
+
+
 int qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitorPtr mon,
                                         virHashTablePtr *ret_stats)
 {
@@ -1907,6 +1941,9 @@ int qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitorPtr mon,
             goto cleanup;
         }
 
+        /* it's ok to not have this information here. Just skip silently. */
+        qemuMonitorJSONDevGetBlockExtent(dev, &bstats->wr_highest_offset);
+
         if (virHashAddEntry(hash, dev_name, bstats) < 0)
             goto cleanup;
         bstats = NULL;
@@ -2076,6 +2113,36 @@ int qemuMonitorJSONGetBlockStatsParamsNumber(qemuMonitorPtr mon,
     return ret;
 }
 
+
+static int
+qemuMonitorJSONReportBlockExtentError(qemuMonitorBlockExtentError error)
+{
+    switch (error) {
+    case QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOPARENT:
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("blockstats parent entry was not in "
+                         "expected format"));
+        break;
+
+    case QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOSTATS:
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("blockstats stats entry was not in "
+                         "expected format"));
+
+    case QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOOFFSET:
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("cannot read %s statistic"),
+                         "wr_highest_offset");
+        break;
+
+    case QEMU_MONITOR_BLOCK_EXTENT_ERROR_OK:
+        return 0;
+    }
+
+    return -1;
+}
+
+
 int qemuMonitorJSONGetBlockExtent(qemuMonitorPtr mon,
                                   const char *dev_name,
                                   unsigned long long *extent)
@@ -2110,9 +2177,8 @@ int qemuMonitorJSONGetBlockExtent(qemuMonitorPtr mon,
 
     for (i = 0; i < virJSONValueArraySize(devices); i++) {
         virJSONValuePtr dev = virJSONValueArrayGet(devices, i);
-        virJSONValuePtr stats;
-        virJSONValuePtr parent;
         const char *thisdev;
+        int err;
         if (!dev || dev->type != VIR_JSON_TYPE_OBJECT) {
             virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                            _("blockstats device entry was not in expected format"));
@@ -2136,24 +2202,9 @@ int qemuMonitorJSONGetBlockExtent(qemuMonitorPtr mon,
             continue;
 
         found = true;
-        if ((parent = virJSONValueObjectGet(dev, "parent")) == NULL ||
+        if ((err = qemuMonitorJSONDevGetBlockExtent(dev, extent)) !=
-            parent->type != VIR_JSON_TYPE_OBJECT) {
+             QEMU_MONITOR_BLOCK_EXTENT_ERROR_OK) {
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+            qemuMonitorJSONReportBlockExtentError(err);
-                           _("blockstats parent entry was not in expected format"));
-            goto cleanup;
-        }
-
-        if ((stats = virJSONValueObjectGet(parent, "stats")) == NULL ||
-            stats->type != VIR_JSON_TYPE_OBJECT) {
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("blockstats stats entry was not in expected format"));
-            goto cleanup;
-        }
-
-        if (virJSONValueObjectGetNumberUlong(stats, "wr_highest_offset", extent) < 0) {
-            virReportError(VIR_ERR_INTERNAL_ERROR,
-                           _("cannot read %s statistic"),
-                           "wr_highest_offset");
             goto cleanup;
         }
     }