[Qemu-devel] [PATCH for-2.5 3/6] Add new block driver interface to add/delete a BDS's child

[Wen Congyang <wency@cn.fujitsu.com>]

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

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
---
 block.c                   | 52 +++++++++++++++++++++++++++++++++++++++++++++++
 include/block/block.h     |  4 ++++
 include/block/block_int.h |  5 +++++
 3 files changed, 61 insertions(+)

diff --git a/block.c b/block.c
index d088ee0..934a32d 100644
--- a/block.c
+++ b/block.c
@@ -4251,3 +4251,55 @@ BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
 {
     return &bs->stats;
 }
+
+static const char *bdrv_get_id_or_node_name(BlockDriverState *bs)
+{
+    if (bs->blk) {
+        return blk_name(bs->blk);
+    }
+
+    return bs->node_name ? bs->node_name : "";
+}
+
+/*
+ * 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 *bs, QDict *options, Error **errp)
+{
+
+    if (!bs->drv || !bs->drv->bdrv_add_child) {
+        error_setg(errp, "The BDS %s doesn't support adding a child",
+                   bdrv_get_id_or_node_name(bs));
+        return;
+    }
+
+    bs->drv->bdrv_add_child(bs, options, errp);
+}
+
+void bdrv_del_child(BlockDriverState *bs, BlockDriverState *child_bs,
+                    Error **errp)
+{
+    BdrvChild *child;
+
+    if (!bs->drv || !bs->drv->bdrv_del_child) {
+        error_setg(errp, "The BDS %s doesn't support removing a child",
+                   bdrv_get_id_or_node_name(bs));
+        return;
+    }
+
+    QLIST_FOREACH(child, &bs->children, next) {
+        if (child->bs == child_bs) {
+            break;
+        }
+    }
+
+    if (!child) {
+        error_setg(errp, "The BDS %s is not the BDS %s's child",
+                   bdrv_get_id_or_node_name(child_bs),
+                   bdrv_get_id_or_node_name(bs));
+        return;
+    }
+
+    bs->drv->bdrv_del_child(bs, child_bs, errp);
+}
diff --git a/include/block/block.h b/include/block/block.h
index 37916f7..4a03fb6 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -616,4 +616,8 @@ void bdrv_flush_io_queue(BlockDriverState *bs);
 
 BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
 
+void bdrv_add_child(BlockDriverState *bs, QDict *options, Error **errp);
+void bdrv_del_child(BlockDriverState *bs, BlockDriverState *child,
+                    Error **errp);
+
 #endif
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 14ad4c3..b6f2905 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -288,6 +288,11 @@ struct BlockDriver {
      */
     int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
 
+    void (*bdrv_add_child)(BlockDriverState *bs, QDict *options,
+                           Error **errp);
+    void (*bdrv_del_child)(BlockDriverState *bs, BlockDriverState *child,
+                           Error **errp);
+
     QLIST_ENTRY(BlockDriver) list;
 };
 
-- 
2.4.3