[Qemu-devel] [PULL 05/17] block: unblock backup operations in backing file

[Stefan Hajnoczi]

From: Wen Congyang <address@hidden>

Signed-off-by: Wen Congyang <address@hidden>
Signed-off-by: Changlong Xie <address@hidden>
Signed-off-by: Wang WeiWei <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
Kashyap Chamarthy <address@hidden>
Message-id: address@hidden
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 block.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/block.c b/block.c
index 101f8c6..66ed1c0 100644
--- a/block.c
+++ b/block.c
@@ -1312,6 +1312,23 @@ 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, neither the source nor the target is the backing file.
+     * 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);
 }
-- 
2.7.4