qcow2: Allow lazy refcounts to be enabled on the command line

qcow2 images now accept a boolean lazy_refcounts options. Use it like
this:

  -drive file=test.qcow2,lazy_refcounts=on

If the option is specified on the command line, it overrides the default
specified by the qcow2 header flags that were set when creating the
image.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/block/qcow2.h b/block/qcow2.h
index 718b52baca..103abdb2c0 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -173,6 +173,7 @@ typedef struct BDRVQcowState {
 
     int flags;
     int qcow_version;
+    bool use_lazy_refcounts;
 
     uint64_t incompatible_features;
     uint64_t compatible_features;