[PATCH v2 03/33] block: Add BdrvChildRole

[Max Reitz]

This enum will supplement BdrvChildClass when it comes to what role (or
combination of roles) a child takes for its parent.

Because empty enums are not allowed, let us just start with it filled.

Signed-off-by: Max Reitz <address@hidden>
---
 include/block/block.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/include/block/block.h b/include/block/block.h
index 38963ef203..0f7e8caa5b 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -279,6 +279,33 @@ enum {
     DEFAULT_PERM_UNCHANGED      = BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH,
 };
 
+typedef enum BdrvChildRole {
+    /* Child stores data */
+    BDRV_CHILD_DATA         = (1 << 0),
+
+    /* Child stores metadata */
+    BDRV_CHILD_METADATA     = (1 << 1),
+
+    /* Filtered child */
+    BDRV_CHILD_FILTERED     = (1 << 2),
+
+    /* Child to COW from (backing child) */
+    BDRV_CHILD_COW          = (1 << 3),
+
+    /*
+     * The primary child.  For most drivers, this is the child whose
+     * filename applies best to the parent node.
+     * Each parent must give this flag to no more than one child at a
+     * time.
+     */
+    BDRV_CHILD_PRIMARY      = (1 << 4),
+
+    /* Useful combination of flags */
+    BDRV_CHILD_IMAGE        = BDRV_CHILD_DATA
+                              | BDRV_CHILD_METADATA
+                              | BDRV_CHILD_PRIMARY,
+} BdrvChildRole;
+
 char *bdrv_perm_names(uint64_t perm);
 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm);
 
-- 
2.24.1