COLO caches all device states in a buffer channel `fb'. Add some comments
explaining the flush, that (1) it's the `fb' not the main channel, (2) on
what it updates.
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/colo.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/migration/colo.c b/migration/colo.c
index f92803dd29..1b94e0f0ee 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -472,12 +472,14 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
qemu_savevm_state_complete_precopy_iterable(s->to_dst_file, false);
qemu_put_byte(s->to_dst_file, QEMU_VM_EOF);
- qemu_fflush(fb);
-
/*
* We need the size of the VMstate data in Secondary side,
* With which we can decide how much data should be read.
+ *
+ * Flush the qemufile cache to make sure both bioc->usage and
+ * bioc->data contains the latest info.
*/
+ qemu_fflush(fb);
colo_send_message_value(s->to_dst_file, COLO_MESSAGE_VMSTATE_SIZE,
bioc->usage, &local_err);
if (local_err) {
--
2.50.1