[Qemu-devel] [PATCH v3 01/25] block/mirror: Small absolute-paths simplification

[Max Reitz]

When invoking drive-mirror in absolute-paths mode, the target's backing
BDS is assigned to it in mirror_complete(). The current logic only does
so if the target does not have that backing BDS already; but it actually
cannot have a backing BDS at all (the BDS is opened with O_NO_BACKING in
qmp_drive_mirror()), so just assert that and assign the new backing BDS
unconditionally.

Signed-off-by: Max Reitz <address@hidden>
---
 block/mirror.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index 301ba92..4ece624 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -888,9 +888,9 @@ static void mirror_complete(BlockJob *job, Error **errp)
 
     if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
         BlockDriverState *backing = s->is_none_mode ? src : s->base;
-        if (backing_bs(target) != backing) {
-            bdrv_set_backing_hd(target, backing);
-        }
+
+        assert(!target->backing);
+        bdrv_set_backing_hd(target, backing);
     }
 
     s->should_complete = true;
-- 
2.10.2