Merge remote-tracking branch 'remotes/jnsnow/tags/bitmaps-pull-request' into staging

Pull request

# gpg: Signature made Wed 04 Jul 2018 07:33:42 BST
# gpg:                using RSA key 7DEF8106AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>"
# Primary key fingerprint: FAEB 9711 A12C F475 812F  18F2 88A9 064D 1835 61EB
#      Subkey fingerprint: F9B7 ABDB BCAC DF95 BE76  CBD0 7DEF 8106 AAFC 390E

* remotes/jnsnow/tags/bitmaps-pull-request:
  dirty-bitmap: fix double lock on bitmap enabling
  block/dirty-bitmap: add bdrv_enable_dirty_bitmap_locked

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block/dirty-bitmap.c

@@ -241,11 +241,18 @@ int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
     return 0;
 }
 
+void bdrv_enable_dirty_bitmap_locked(BdrvDirtyBitmap *bitmap)
+{
+    assert(!bdrv_dirty_bitmap_frozen(bitmap));
+    bitmap->disabled = false;
+}
+
 /* Called with BQL taken. */
 void bdrv_dirty_bitmap_enable_successor(BdrvDirtyBitmap *bitmap)
 {
+    assert(bitmap->mutex == bitmap->successor->mutex);
     qemu_mutex_lock(bitmap->mutex);
-    bdrv_enable_dirty_bitmap(bitmap->successor);
+    bdrv_enable_dirty_bitmap_locked(bitmap->successor);
     qemu_mutex_unlock(bitmap->mutex);
 }
 
@@ -424,8 +431,7 @@ void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
 void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
 {
     bdrv_dirty_bitmap_lock(bitmap);
-    assert(!bdrv_dirty_bitmap_frozen(bitmap));
-    bitmap->disabled = false;
+    bdrv_enable_dirty_bitmap_locked(bitmap);
     bdrv_dirty_bitmap_unlock(bitmap);
 }
 

include/block/dirty-bitmap.h

@@ -32,6 +32,7 @@ void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs,
                                          Error **errp);
 void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
+void bdrv_enable_dirty_bitmap_locked(BdrvDirtyBitmap *bitmap);
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
 uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs);
 uint32_t bdrv_dirty_bitmap_granularity(const BdrvDirtyBitmap *bitmap);

migration/block-dirty-bitmap.c

@@ -511,7 +511,7 @@ void dirty_bitmap_mig_before_vm_start(void)
         DirtyBitmapLoadBitmapState *b = item->data;
 
         if (b->migrated) {
-            bdrv_enable_dirty_bitmap(b->bitmap);
+            bdrv_enable_dirty_bitmap_locked(b->bitmap);
         } else {
             bdrv_dirty_bitmap_enable_successor(b->bitmap);
         }
@@ -547,7 +547,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
         if (enabled_bitmaps == NULL) {
             /* in postcopy */
             bdrv_reclaim_dirty_bitmap_locked(s->bs, s->bitmap, &error_abort);
-            bdrv_enable_dirty_bitmap(s->bitmap);
+            bdrv_enable_dirty_bitmap_locked(s->bitmap);
         } else {
             /* target not started, successor must be empty */
             int64_t count = bdrv_get_dirty_count(s->bitmap);