2 files changed, 30 insertions, 1 deletions
diff --git a/include/block/block.h b/include/block/block.h
index f6fb8c497b..07bb724f7d 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -12,6 +12,7 @@
 /* block.c */
 typedef struct BlockDriver BlockDriver;
 typedef struct BlockJob BlockJob;
+typedef struct BdrvChildRole BdrvChildRole;
 
 typedef struct BlockDriverInfo {
     /* in bytes, 0 if irrelevant */
@@ -90,6 +91,14 @@ typedef struct HDGeometry {
 
 #define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
 
+
+/* Option names of options parsed by the block layer */
+
+#define BDRV_OPT_CACHE_WB       "cache.writeback"
+#define BDRV_OPT_CACHE_DIRECT   "cache.direct"
+#define BDRV_OPT_CACHE_NO_FLUSH "cache.no-flush"
+
+
 #define BDRV_SECTOR_BITS   9
 #define BDRV_SECTOR_SIZE   (1ULL << BDRV_SECTOR_BITS)
 #define BDRV_SECTOR_MASK   ~(BDRV_SECTOR_SIZE - 1)
@@ -196,7 +205,8 @@ void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top);
 int bdrv_parse_cache_flags(const char *mode, int *flags);
 int bdrv_parse_discard_flags(const char *mode, int *flags);
 int bdrv_open_image(BlockDriverState **pbs, const char *filename,
-                    QDict *options, const char *bdref_key, int flags,
+                    QDict *options, const char *bdref_key,
+                    BlockDriverState* parent, const BdrvChildRole *child_role,
                     bool allow_none, Error **errp);
 void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd);
 int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index b174852099..888ec09e96 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -330,6 +330,19 @@ typedef struct BdrvAioNotifier {
     QLIST_ENTRY(BdrvAioNotifier) list;
 } BdrvAioNotifier;
 
+struct BdrvChildRole {
+    int (*inherit_flags)(int parent_flags);
+};
+
+extern const BdrvChildRole child_file;
+extern const BdrvChildRole child_format;
+
+typedef struct BdrvChild {
+    BlockDriverState *bs;
+    const BdrvChildRole *role;
+    QLIST_ENTRY(BdrvChild) next;
+} BdrvChild;
+
 /*
  * Note: the function bdrv_append() copies and swaps contents of
  * BlockDriverStates, so if you add new fields to this struct, please
@@ -429,6 +442,12 @@ struct BlockDriverState {
     /* long-running background operation */
     BlockJob *job;
 
+    /* The node that this node inherited default options from (and a reopen on
+     * which can affect this node by changing these defaults). This is always a
+     * parent node of this node. */
+    BlockDriverState *inherits_from;
+    QLIST_HEAD(, BdrvChild) children;
+
     QDict *options;
     BlockdevDetectZeroesOptions detect_zeroes;