[PATCH v2 3/5] block: improve bdrv_child_get_parent_desc()

[Vladimir Sementsov-Ogievskiy]

We have different types of parents: block nodes, block backends and
jobs. So, it makes sense to specify type together with name.

Next, this handler us used to compose an error message about permission
conflict. And permission conflict occurs in a specific place of block
graph. We shouldn't report name of parent device (as it refers another
place in block graph), but exactly and only the name of the node. So,
use bdrv_get_node_name() directly.

iotest 283 output is updated.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block.c                    | 2 +-
 tests/qemu-iotests/283.out | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index b9df90d61d..54a3da9311 100644
--- a/block.c
+++ b/block.c
@@ -1152,7 +1152,7 @@ int bdrv_parse_cache_mode(const char *mode, int *flags, 
bool *writethrough)
 static char *bdrv_child_get_parent_desc(BdrvChild *c)
 {
     BlockDriverState *parent = c->opaque;
-    return g_strdup(bdrv_get_device_or_node_name(parent));
+    return g_strdup_printf("node '%s'", bdrv_get_node_name(parent));
 }
 
 static void bdrv_child_cb_drained_begin(BdrvChild *child)
diff --git a/tests/qemu-iotests/283.out b/tests/qemu-iotests/283.out
index 97e62a4c94..c9397bfc44 100644
--- a/tests/qemu-iotests/283.out
+++ b/tests/qemu-iotests/283.out
@@ -5,7 +5,7 @@
 {"execute": "blockdev-add", "arguments": {"driver": "blkdebug", "image": 
"base", "node-name": "other", "take-child-perms": ["write"]}}
 {"return": {}}
 {"execute": "blockdev-backup", "arguments": {"device": "source", "sync": 
"full", "target": "target"}}
-{"error": {"class": "GenericError", "desc": "Cannot append backup-top filter: 
Conflicts with use by source as 'image', which does not allow 'write' on base"}}
+{"error": {"class": "GenericError", "desc": "Cannot append backup-top filter: 
Conflicts with use by node 'source' as 'image', which does not allow 'write' on 
base"}}
 
 === backup-top should be gone after job-finalize ===
 
-- 
2.29.2