[Qemu-devel] [PATCH V3 6/7] block: Add backing file loop check in qcow2_change_backing_file()

[Xu Wang <cngesaint@gmail.com>]

Add backing file loop check before execute change backing file for
qcow2 format.

Signed-off-by: Xu Wang <cngesaint@gmail.com>
---
 block/qcow2.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/block/qcow2.c b/block/qcow2.c
index 0eceefe..01bd7d5 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1195,6 +1195,12 @@ fail:
 static int qcow2_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt)
 {
+    /* Check if loop exists in backing files chain after changed */
+    if (bdrv_backing_file_loop_check(bs->filename,
+                                     bs->drv ? bs->drv->format_name : NULL,
+                                     backing_file, backing_fmt)) {
+        return -EIO;
+    }
     pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
     pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
 
-- 
1.8.1.4