[PATCH RFC] qapi: Allow getting flat output from 'query-named-block-nodes'

[Peter Krempa <pkrempa@redhat.com>]

When a management application manages node names there's no reason to
recurse into backing images in the output of query-named-block-nodes.

Add a parameter to the command which will return just the top level
structs.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
 block.c               |  5 +++--
 block/qapi.c          | 10 ++++++++--
 blockdev.c            | 12 ++++++++++--
 include/block/block.h |  2 +-
 include/block/qapi.h  |  4 +++-
 monitor/hmp-cmds.c    |  2 +-
 qapi/block-core.json  |  6 +++++-
 7 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/block.c b/block.c
index 473eb6eeaa..b30bdfa0d3 100644
--- a/block.c
+++ b/block.c
@@ -4766,14 +4766,15 @@ BlockDriverState *bdrv_find_node(const char *node_name)
 }

 /* Put this QMP function here so it can access the static graph_bdrv_states. */
-BlockDeviceInfoList *bdrv_named_nodes_list(Error **errp)
+BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
+                                           Error **errp)
 {
     BlockDeviceInfoList *list, *entry;
     BlockDriverState *bs;

     list = NULL;
     QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
-        BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, errp);
+        BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
         if (!info) {
             qapi_free_BlockDeviceInfoList(list);
             return NULL;
diff --git a/block/qapi.c b/block/qapi.c
index 9a5d0c9b27..84048e1a57 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -42,7 +42,9 @@
 #include "qemu/cutils.h"

 BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
-                                        BlockDriverState *bs, Error **errp)
+                                        BlockDriverState *bs,
+                                        bool flat,
+                                        Error **errp)
 {
     ImageInfo **p_image_info;
     BlockDriverState *bs0;
@@ -156,6 +158,10 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
             return NULL;
         }

+        /* stop gathering data for flat output */
+        if (flat)
+            break;
+
         if (bs0->drv && bs0->backing) {
             info->backing_file_depth++;
             bs0 = bs0->backing->bs;
@@ -389,7 +395,7 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,

     if (bs && bs->drv) {
         info->has_inserted = true;
-        info->inserted = bdrv_block_device_info(blk, bs, errp);
+        info->inserted = bdrv_block_device_info(blk, bs, false, errp);
         if (info->inserted == NULL) {
             goto err;
         }
diff --git a/blockdev.c b/blockdev.c
index 8e029e9c01..5f9c5e258f 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3707,9 +3707,17 @@ void qmp_drive_backup(DriveBackup *arg, Error **errp)
     }
 }

-BlockDeviceInfoList *qmp_query_named_block_nodes(Error **errp)
+BlockDeviceInfoList *qmp_query_named_block_nodes(bool has_flat,
+                                                 bool flat,
+                                                 Error **errp)
 {
-    return bdrv_named_nodes_list(errp);
+    bool return_flat = false;
+
+    if (has_flat) {
+        return_flat = flat;
+    }
+
+    return bdrv_named_nodes_list(return_flat, errp);
 }

 XDbgBlockGraph *qmp_x_debug_query_block_graph(Error **errp)
diff --git a/include/block/block.h b/include/block/block.h
index 1df9848e74..177ba09e3f 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -468,7 +468,7 @@ void bdrv_lock_medium(BlockDriverState *bs, bool locked);
 void bdrv_eject(BlockDriverState *bs, bool eject_flag);
 const char *bdrv_get_format_name(BlockDriverState *bs);
 BlockDriverState *bdrv_find_node(const char *node_name);
-BlockDeviceInfoList *bdrv_named_nodes_list(Error **errp);
+BlockDeviceInfoList *bdrv_named_nodes_list(bool flat, Error **errp);
 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp);
 BlockDriverState *bdrv_lookup_bs(const char *device,
                                  const char *node_name,
diff --git a/include/block/qapi.h b/include/block/qapi.h
index cd9410dee3..22c7807c89 100644
--- a/include/block/qapi.h
+++ b/include/block/qapi.h
@@ -29,7 +29,9 @@
 #include "block/snapshot.h"

 BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
-                                        BlockDriverState *bs, Error **errp);
+                                        BlockDriverState *bs,
+                                        bool flat,
+                                        Error **errp);
 int bdrv_query_snapshot_info_list(BlockDriverState *bs,
                                   SnapshotInfoList **p_list,
                                   Error **errp);
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index b2551c16d1..651969819b 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -620,7 +620,7 @@ void hmp_info_block(Monitor *mon, const QDict *qdict)
     }

     /* Print node information */
-    blockdev_list = qmp_query_named_block_nodes(NULL);
+    blockdev_list = qmp_query_named_block_nodes(false, false, NULL);
     for (blockdev = blockdev_list; blockdev; blockdev = blockdev->next) {
         assert(blockdev->value->has_node_name);
         if (device && strcmp(device, blockdev->value->node_name)) {
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 0cf68fea14..bd651106bd 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1752,6 +1752,8 @@
 #
 # Get the named block driver list
 #
+# @flat: don't recurse into backing images if true. Default is false (Since 5.0)
+#
 # Returns: the list of BlockDeviceInfo
 #
 # Since: 2.0
@@ -1805,7 +1807,9 @@
 #                    } } ] }
 #
 ##
-{ 'command': 'query-named-block-nodes', 'returns': [ 'BlockDeviceInfo' ] }
+{ 'command': 'query-named-block-nodes',
+  'returns': [ 'BlockDeviceInfo' ],
+  'data': { '*flat': 'bool' } }

 ##
 # @XDbgBlockGraphNodeType:
-- 
2.23.0