[Qemu-devel] [PATCH v2] qapi: Add "backing" to BlockStats

[Fam Zheng <famz@redhat.com>]

Currently there is no way to query BlockStats of the backing chain. This
adds "backing" field into BlockStats to make it possible.

The comment of "parent" is reworded.

Signed-off-by: Fam Zheng <famz@redhat.com>

---
v2: Only add "backing", drop "file".

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/qapi.c     |  5 +++++
 qapi-schema.json | 10 ++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/block/qapi.c b/block/qapi.c
index a32cb79..98b1b83 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -318,6 +318,11 @@ BlockStats *bdrv_query_stats(const BlockDriverState *bs)
         s->parent = bdrv_query_stats(bs->file);
     }
 
+    if (bs->backing_hd) {
+        s->has_backing = true;
+        s->backing = bdrv_query_stats(bs->backing_hd);
+    }
+
     return s;
 }
 
diff --git a/qapi-schema.json b/qapi-schema.json
index f27c48a..0e534d0 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1022,15 +1022,17 @@
 #
 # @stats:  A @BlockDeviceStats for the device.
 #
-# @parent: #optional This may point to the backing block device if this is a
-#          a virtual block device.  If it's a backing block, this will point
-#          to the backing file is one is present.
+# @parent: #optional This describes the file block device if it has one.
+#
+# @backing: #optional This describes the backing block device if it has one.
+#           (Since 2.0)
 #
 # Since: 0.14.0
 ##
 { 'type': 'BlockStats',
   'data': {'*device': 'str', 'stats': 'BlockDeviceStats',
-           '*parent': 'BlockStats'} }
+           '*parent': 'BlockStats',
+           '*backing': 'BlockStats'} }
 
 ##
 # @query-blockstats:
-- 
1.8.5.3