[v14,1/3] Add new block driver interface to add/delete a BDS's child

Commit Message

Changlong Xie May 10, 2016, 7:36 a.m. UTC

From: Wen Congyang <[e-mail]>

In some cases, we want to take a quorum child offline, and take
another child online.

Signed-off-by: Wen Congyang <[e-mail]>
Signed-off-by: zhanghailiang <[e-mail]>
Signed-off-by: Gonglei <[e-mail]>
Signed-off-by: Changlong Xie <[e-mail]>
Reviewed-by: Max Reitz <[e-mail]>
Reviewed-by: Alberto Garcia <[e-mail]>
---
 block.c                   | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 include/block/block.h     |  4 ++++
 include/block/block_int.h |  5 +++++
 3 files changed, 58 insertions(+)

Patch

diff --git a/block.c b/block.c
index d4939b4..68cd3b2 100644
--- a/block.c
+++ b/block.c
@@ -3981,3 +3981,52 @@  void bdrv_refresh_filename(BlockDriverState *bs)
         QDECREF(json);
     }
 }
+
+/*
+ * Hot add/remove a BDS's child. So the user can take a child offline when
+ * it is broken and take a new child online
+ */
+void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
+                    Error **errp)
+{
+
+    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
+        error_setg(errp, "The node %s does not support adding a child",
+                   bdrv_get_device_or_node_name(parent_bs));
+        return;
+    }
+
+    if (!QLIST_EMPTY(&child_bs->parents)) {
+        error_setg(errp, "The node %s already has a parent",
+                   child_bs->node_name);
+        return;
+    }
+
+    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
+}
+
+void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
+{
+    BdrvChild *tmp;
+
+    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
+        error_setg(errp, "The node %s does not support removing a child",
+                   bdrv_get_device_or_node_name(parent_bs));
+        return;
+    }
+
+    QLIST_FOREACH(tmp, &parent_bs->children, next) {
+        if (tmp == child) {
+            break;
+        }
+    }
+
+    if (!tmp) {
+        error_setg(errp, "The node %s does not have a child named %s",
+                   bdrv_get_device_or_node_name(parent_bs),
+                   bdrv_get_device_or_node_name(child->bs));
+        return;
+    }
+
+    parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
+}
diff --git a/include/block/block.h b/include/block/block.h
index 3a73137..694ca76 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -541,4 +541,8 @@  void bdrv_drained_begin(BlockDriverState *bs);
  */
 void bdrv_drained_end(BlockDriverState *bs);
 
+void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
+                    Error **errp);
+void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp);
+
 #endif
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 10d8759..7e238a0 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -317,6 +317,11 @@  struct BlockDriver {
      */
     void (*bdrv_drain)(BlockDriverState *bs);
 
+    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
+                           Error **errp);
+    void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child,
+                           Error **errp);
+
     QLIST_ENTRY(BlockDriver) list;
 };