[Qemu-devel] [PATCH 2/4] qcow2: handle reopening bitmaps on bdrv_invalidate_cache

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Consider migration with shared storage. Persistent bitmaps are stored
on bdrv_inactivate. Then, on destination
process_incoming_migration_bh() calls bdrv_invalidate_cache_all() which
leads to qcow2_load_autoloading_dirty_bitmaps() which fails if bitmaps
are already loaded on destination start. In this case we should call
qcow2_reopen_bitmaps_rw instead.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/qcow2.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 1914a940e5..f5f205e1b7 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1450,7 +1450,13 @@ static int qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
         s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
     }
 
-    if (qcow2_load_autoloading_dirty_bitmaps(bs, &local_err)) {
+    if (bdrv_has_readonly_bitmaps(bs)) {
+        if (!bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE)) {
+            bool header_updated = false;
+            qcow2_reopen_bitmaps_rw_hint(bs, &header_updated, &local_err);
+            update_header = update_header && !header_updated;
+        }
+    } else if (qcow2_load_autoloading_dirty_bitmaps(bs, &local_err)) {
         update_header = false;
     }
     if (local_err != NULL) {
-- 
2.11.1