block: Add BdrvChildRole.get_parent_desc()

For meaningful error messages in the permission system, we need to get
some human-readable description of the parent of a BdrvChild.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/block.c b/block.c
index 5f2dd6fa47..e03cc5da42 100644
--- a/block.c
+++ b/block.c
@@ -707,6 +707,12 @@ int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
     return 0;
 }
 
+static char *bdrv_child_get_parent_desc(BdrvChild *c)
+{
+    BlockDriverState *parent = c->opaque;
+    return g_strdup(bdrv_get_device_or_node_name(parent));
+}
+
 static void bdrv_child_cb_drained_begin(BdrvChild *child)
 {
     BlockDriverState *bs = child->opaque;
@@ -774,6 +780,7 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options,
 }
 
 const BdrvChildRole child_file = {
+    .get_parent_desc = bdrv_child_get_parent_desc,
     .inherit_options = bdrv_inherited_options,
     .drained_begin   = bdrv_child_cb_drained_begin,
     .drained_end     = bdrv_child_cb_drained_end,
@@ -794,6 +801,7 @@ static void bdrv_inherited_fmt_options(int *child_flags, QDict *child_options,
 }
 
 const BdrvChildRole child_format = {
+    .get_parent_desc = bdrv_child_get_parent_desc,
     .inherit_options = bdrv_inherited_fmt_options,
     .drained_begin   = bdrv_child_cb_drained_begin,
     .drained_end     = bdrv_child_cb_drained_end,
@@ -824,6 +832,7 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
 }
 
 const BdrvChildRole child_backing = {
+    .get_parent_desc = bdrv_child_get_parent_desc,
     .inherit_options = bdrv_backing_options,
     .drained_begin   = bdrv_child_cb_drained_begin,
     .drained_end     = bdrv_child_cb_drained_end,