[Qemu-block] [PATCH v7 11/20] block: Don't lock drive-backup target image in none mode

[Fam Zheng]

As a very special case, in sync=none mode, the source is the backing image of
the target, which will be RO opened again. This won't work with image locking
because the first open could be exclusive.

Signed-off-by: Fam Zheng <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
---
 blockdev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/blockdev.c b/blockdev.c
index a9032b9..55b0fde 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3233,6 +3233,11 @@ static void do_drive_backup(const char *job_id, const 
char *device,
         }
     }
     if (sync == MIRROR_SYNC_MODE_NONE) {
+        /* XXX: bs will be open second time as the backing file of target,
+         * disable image locking. Once block layer allows sharing backing BDS,
+         * change below to BDRV_O_NO_BACKING and assign it after bdrv_open().
+         **/
+        flags |= BDRV_O_NO_LOCK;
         source = bs;
     }
 
-- 
2.7.4