[Qemu-devel] [PATCH v11 01/12] unblock backup operations in backing file

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

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 block.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/block.c b/block.c
index 9a2ab68..1d6c115 100644
--- a/block.c
+++ b/block.c
@@ -1161,6 +1161,24 @@ void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
     /* Otherwise we won't be able to commit due to check in bdrv_commit */
     bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
                     bs->backing_blocker);
+    /*
+     * We do backup in 3 ways:
+     * 1. drive backup
+     *    The target bs is new opened, and the source is top BDS
+     * 2. blockdev backup
+     *    Both the source and the target are top BDSes.
+     * 3. internal backup(used for block replication)
+     *    Both the source and the target are backing file
+     *
+     * In case 1, and 2, the backing file is neither the source nor
+     * the target.
+     * In case 3, we will block the top BDS, so there is only one block
+     * job for the top BDS and its backing chain.
+     */
+    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
+                    bs->backing_blocker);
+    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
+                    bs->backing_blocker);
 out:
     bdrv_refresh_limits(bs, NULL);
 }
-- 
2.4.3