@@ -1462,7 +1462,10 @@ void qmp_drive_backup(const char *device, const char *target,
}
if (!has_format) {
- format = mode == NEW_IMAGE_MODE_EXISTING ? NULL : bs->drv->format_name;
+ format = NULL;
+ if (mode != NEW_IMAGE_MODE_EXISTING) {
+ format = sync == MIRROR_SYNC_MODE_NONE ? "qcow2" : bs->drv->format_name;
+ }
}
if (format) {
drv = bdrv_find_format(format);
@@ -1806,6 +1806,7 @@
#
# @format: #optional the format of the new destination, default is to
# probe if @mode is 'existing', else the format of the source
+# drive. If @sync is 'none' then the default is qcow2.
#
# @sync: what parts of the disk image should be copied to the destination
# (all the disk, only the sectors allocated in the topmost image, or
qcow2 supports backing files so it makes sense to default to qcow2 for MIRROR_SYNC_MODE_NONE so that we can use the source as a backing drive and export it via nbd. Defaulting FULL and TOP to SYNC_MODE_NONE breaks tests but that could be fixed if we wanted it. Signed-off-by: Ian Main <imain@redhat.com> --- blockdev.c | 5 ++++- qapi-schema.json | 1 + 2 files changed, 5 insertions(+), 1 deletion(-)