[Qemu-block] [PATCH v2 2/9] block: User BdrvChild callback for device name

[Kevin Wolf]

In order to get rid of bs->blk for bdrv_get_device_name() and
bdrv_get_device_or_node_name(), ask all parents for their name and
simply pick the first one.

Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
---
 block.c                   | 22 ++++++++++++++++++++--
 block/block-backend.c     |  6 ++++++
 include/block/block_int.h |  5 +++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index 69ee791..a8df72f 100644
--- a/block.c
+++ b/block.c
@@ -2896,10 +2896,28 @@ const char *bdrv_get_node_name(const BlockDriverState 
*bs)
     return bs->node_name;
 }
 
+static const char *bdrv_get_parent_name(const BlockDriverState *bs)
+{
+    BdrvChild *c;
+    const char *name;
+
+    /* If multiple parents have a name, just pick the first one. */
+    QLIST_FOREACH(c, &bs->parents, next_parent) {
+        if (c->role->get_name) {
+            name = c->role->get_name(c);
+            if (name && *name) {
+                return name;
+            }
+        }
+    }
+
+    return NULL;
+}
+
 /* TODO check what callers really want: bs->node_name or blk_name() */
 const char *bdrv_get_device_name(const BlockDriverState *bs)
 {
-    return bs->blk ? blk_name(bs->blk) : "";
+    return bdrv_get_parent_name(bs) ?: "";
 }
 
 /* This can be used to identify nodes that might not have a device
@@ -2908,7 +2926,7 @@ const char *bdrv_get_device_name(const BlockDriverState 
*bs)
  * absent, then this returns an empty (non-null) string. */
 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
 {
-    return bs->blk ? blk_name(bs->blk) : bs->node_name;
+    return bdrv_get_parent_name(bs) ?: bs->node_name;
 }
 
 int bdrv_get_flags(BlockDriverState *bs)
diff --git a/block/block-backend.c b/block/block-backend.c
index 7f507ba..34f747e 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -97,11 +97,17 @@ static void blk_root_drained_end(BdrvChild *child);
 static void blk_root_change_media(BdrvChild *child, bool load);
 static void blk_root_resize(BdrvChild *child);
 
+static const char *blk_root_get_name(BdrvChild *child)
+{
+    return blk_name(child->opaque);
+}
+
 static const BdrvChildRole child_root = {
     .inherit_options    = blk_root_inherit_options,
 
     .change_media       = blk_root_change_media,
     .resize             = blk_root_resize,
+    .get_name           = blk_root_get_name,
 
     .drained_begin      = blk_root_drained_begin,
     .drained_end        = blk_root_drained_end,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 9938a3d..f4a0941 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -365,6 +365,11 @@ struct BdrvChildRole {
     void (*change_media)(BdrvChild *child, bool load);
     void (*resize)(BdrvChild *child);
 
+    /* Returns a name that is supposedly more useful for human users than the
+     * node name for identifying the node in question (in particular, a BB
+     * name), or NULL if the parent can't provide a better name. */
+    const char* (*get_name)(BdrvChild *child);
+
     void (*drained_begin)(BdrvChild *child);
     void (*drained_end)(BdrvChild *child);
 };
-- 
1.8.3.1