[PULL 14/24] migration/block-dirty-bitmap: simplify dirty_bitmap_load_complete

[Eric Blake <eblake@redhat.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

bdrv_enable_dirty_bitmap_locked() call does nothing, as if we are in
postcopy, bitmap successor must be enabled, and reclaim operation will
enable the bitmap.

So, actually we need just call _reclaim_ in both if branches, and
making differences only to add an assertion seems not really good. The
logic becomes simple: on load complete we do reclaim and that's all.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-14-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 9194807b54f1..405a259296d9 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -603,6 +603,10 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)

     qemu_mutex_lock(&s->lock);

+    if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
+        bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
+    }
+
     for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;

@@ -612,27 +616,6 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
         }
     }

-    if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
-        bdrv_dirty_bitmap_lock(s->bitmap);
-        if (s->enabled_bitmaps == NULL) {
-            /* in postcopy */
-            bdrv_reclaim_dirty_bitmap_locked(s->bitmap, &error_abort);
-            bdrv_enable_dirty_bitmap_locked(s->bitmap);
-        } else {
-            /* target not started, successor must be empty */
-            int64_t count = bdrv_get_dirty_count(s->bitmap);
-            BdrvDirtyBitmap *ret = bdrv_reclaim_dirty_bitmap_locked(s->bitmap,
-                                                                    NULL);
-            /* bdrv_reclaim_dirty_bitmap can fail only on no successor (it
-             * must be) or on merge fail, but merge can't fail when second
-             * bitmap is empty
-             */
-            assert(ret == s->bitmap &&
-                   count == bdrv_get_dirty_count(s->bitmap));
-        }
-        bdrv_dirty_bitmap_unlock(s->bitmap);
-    }
-
     qemu_mutex_unlock(&s->lock);
 }

-- 
2.27.0