[Qemu-devel] [PATCH v3 18/27] mirror: Disable image locking on target backing chain

[Fam Zheng <famz@redhat.com>]

In sync=none the backing image of s->target is s->common.bs, which could
be exclusively locked, the image locking wouldn't work here.

Later we can update completion code to lock it after the replaced node
has dropped its lock.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 blockdev.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/blockdev.c b/blockdev.c
index e3882d6..9968568 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3617,6 +3617,12 @@ void qmp_drive_mirror(const char *device, const char *target,
      * file.
      */
     target_bs = NULL;
+    if (sync == MIRROR_SYNC_MODE_NONE) {
+        flags |= BDRV_O_NO_LOCK;
+    }
+    /* TODO: in mirror complete, after target_bs is switched to and the
+     * original BDS's lock is dropped, we should enable the lock on target_bs.
+     * */
     ret = bdrv_open(&target_bs, target, NULL, options,
                     flags | BDRV_O_NO_BACKING, &local_err);
     if (ret < 0) {
-- 
2.8.0