From 11212d8fa08a4e5bd56bb4f6877f9a4c0439a02b Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 4 Sep 2013 19:00:27 +0200
Subject: block: make bdrv_has_zero_init return false for copy-on-write-images

This helps implementing is_allocated on top of get_block_status.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block.c | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'block.c')

diff --git a/block.c b/block.c
index 5df17de5a4..2a90893464 100644
--- a/block.c
+++ b/block.c
@@ -3031,6 +3031,11 @@ int bdrv_has_zero_init(BlockDriverState *bs)
 {
     assert(bs->drv);
 
+    /* If BS is a copy on write image, it is initialized to
+       the contents of the base image, which may not be zeroes.  */
+    if (bs->backing_hd) {
+        return 0;
+    }
     if (bs->drv->bdrv_has_zero_init) {
         return bs->drv->bdrv_has_zero_init(bs);
     }
-- 
cgit v1.2.3