If the image version should be upgraded, that is the first we should do;
if it should be downgraded, that is the last we should do. So split the
version change block into an upgrade part at the start and a downgrade
part at the end.
Signed-off-by: Max Reitz <mre...@redhat.com>
Reviewed-by: Eric Blake <ebl...@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
---
block/qcow2.c | 31 ++++++++++++++++---------------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 258e0df..6f9e4c8 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2737,20 +2737,13 @@ static int qcow2_amend_options(BlockDriverState *bs,
QemuOpts *opts,
desc++;
}
- if (new_version != old_version) {
- if (new_version > old_version) {
- /* Upgrade */
- s->qcow_version = new_version;
- ret = qcow2_update_header(bs);
- if (ret < 0) {
- s->qcow_version = old_version;
- return ret;
- }
- } else {
- ret = qcow2_downgrade(bs, new_version, status_cb, cb_opaque);
- if (ret < 0) {
- return ret;
- }
+ /* Upgrade first (some features may require compat=1.1) */
+ if (new_version > old_version) {
+ s->qcow_version = new_version;
+ ret = qcow2_update_header(bs);
+ if (ret < 0) {
+ s->qcow_version = old_version;
+ return ret;
}
}
@@ -2764,7 +2757,7 @@ static int qcow2_amend_options(BlockDriverState *bs,
QemuOpts *opts,
if (s->use_lazy_refcounts != lazy_refcounts) {
if (lazy_refcounts) {
- if (s->qcow_version < 3) {
+ if (new_version < 3) {
error_report("Lazy refcounts only supported with compatibility
"
"level 1.1 and above (use compat=1.1 or
greater)");
return -EINVAL;
@@ -2800,6 +2793,14 @@ static int qcow2_amend_options(BlockDriverState *bs,
QemuOpts *opts,
}
}
+ /* Downgrade last (so unsupported features can be removed before) */
+ if (new_version < old_version) {
+ ret = qcow2_downgrade(bs, new_version, status_cb, cb_opaque);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
return 0;
}
--
1.9.3
