commit 5669b44de5b3b607a3a4749e0c8c5ddfd723e76b
author Kevin Wolf <kwolf@redhat.com> Fri Apr 11 21:36:45 2014 +0200
committer Kevin Wolf <kwolf@redhat.com> Wed Apr 30 11:05:00 2014 +0200
tree 40acd9208df98e76a8f7d09c776f2603f244c1a9
parent 317fc44ef2bfa87e96adecf035ed136ed9d78c8f

block: Remove BDRV_O_COPY_ON_READ for bs->file

Copy on Read makes sense on the format level where backing files are
implemented, but it's not required on the protocol level. While it
shouldn't actively break anything to have COR enabled on both layers,
needless serialisation and allocation checks may impact performance.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

block.c

diff --git a/block.c b/block.c
index c6d5ab9..9f88bcc 100644
--- a/block.c
+++ b/block.c
@@ -793,7 +793,7 @@
     }
 
     /* Clear flags that only apply to the top layer */
-    flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
+    flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
 
     return flags;
 }