[Qemu-devel] [PATCH v20 12/15] block: Allow backup on referenced named BlockDriverState

[Fam Zheng <famz@redhat.com>]

Drive backup is a read only operation on source bs. We want to allow
this specific case to enable image-fleecing. Note that when
image-fleecing job starts, the job still add its blocker to source bs,
and any other operation on it will be blocked by that.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block.c b/block.c
index e0d7984..2aebf45 100644
--- a/block.c
+++ b/block.c
@@ -1120,6 +1120,8 @@ 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(bs->backing_hd, BLOCK_OP_TYPE_COMMIT,
                     bs->backing_blocker);
+    bdrv_op_unblock(bs->backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
+                    bs->backing_blocker);
 out:
     bdrv_refresh_limits(bs);
 }
-- 
1.9.2