[Qemu-devel] [RFC PATCH 5/8] block: add a callback layer for common functions

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

This structure can hold some call back functions, such as
event emit, error printf. By using call back, block layer
can be decoupled with other components.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
---
 block.c               |    7 +++++++
 include/block/block.h |   11 +++++++++++
 2 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/block.c b/block.c
index 07385bf..576b86e 100644
--- a/block.c
+++ b/block.c
@@ -55,6 +55,13 @@ typedef enum {
     BDRV_REQ_ZERO_WRITE   = 0x2,
 } BdrvRequestFlags;
 
+BDRVCommonHooks bdrv_common_hooks;
+
+void bdrv_set_common_hooks(BDRVCommonHooks *hooks)
+{
+    bdrv_common_hooks = *hooks;
+}
+
 static void bdrv_dev_change_media_cb(BlockDriverState *bs, bool load);
 static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
diff --git a/include/block/block.h b/include/block/block.h
index 728ec1a..7913f48 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -119,6 +119,17 @@ typedef struct BDRVReopenState {
     void *opaque;
 } BDRVReopenState;
 
+/*
+ * Now all block layer use same hooks, If needed it can be changed as per
+ * bds.
+ */
+typedef struct BDRVCommonHooks {
+    void (*hooks)(void *);
+} BDRVCommonHooks;
+
+extern BDRVCommonHooks bdrv_common_hooks;
+
+void bdrv_set_common_hooks(BDRVCommonHooks *hooks);
 
 void bdrv_iostatus_enable(BlockDriverState *bs);
 void bdrv_iostatus_reset(BlockDriverState *bs);
-- 
1.7.1