[Qemu-devel] [PATCH V7 3/4] block: Add backing file loop check in change_backing_file()

[Xu Wang]

Backing file loop should be checked before calling change_backing_
file(). If loop appeared, this calling should be stopped and an
error printed.

Signed-off-by: Xu Wang <address@hidden>
---
 block.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block.c b/block.c
index c2ed6ef..861b133 100644
--- a/block.c
+++ b/block.c
@@ -2083,6 +2083,11 @@ int bdrv_change_backing_file(BlockDriverState *bs,
         return -EINVAL;
     }
 
+    /* Check if loop exists in backing files chain after change */
+    if (!bdrv_backing_chain_okay(backing_file, backing_fmt, bs->filename)) {
+        return -EIO;
+    }
+
     if (drv->bdrv_change_backing_file != NULL) {
         ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
     } else {
-- 
1.8.1.4