qmp: add persistent flag to block-dirty-bitmap-add

Add optional 'persistent' flag to qmp command block-dirty-bitmap-add.
Default is false.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20170628120530.31251-24-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

blockdev.c

@@ -1983,6 +1983,7 @@ static void block_dirty_bitmap_add_prepare(BlkActionState *common,
     /* AIO context taken and released within qmp_block_dirty_bitmap_add */
     qmp_block_dirty_bitmap_add(action->node, action->name,
                                action->has_granularity, action->granularity,
+                               action->has_persistent, action->persistent,
                                &local_err);
 
     if (!local_err) {
@@ -2708,9 +2709,11 @@ out:
 
 void qmp_block_dirty_bitmap_add(const char *node, const char *name,
                                 bool has_granularity, uint32_t granularity,
+                                bool has_persistent, bool persistent,
                                 Error **errp)
 {
     BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
 
     if (!name || name[0] == '\0') {
         error_setg(errp, "Bitmap name cannot be empty");
@@ -2733,7 +2736,20 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
         granularity = bdrv_get_default_bitmap_granularity(bs);
     }
 
-    bdrv_create_dirty_bitmap(bs, granularity, name, errp);
+    if (!has_persistent) {
+        persistent = false;
+    }
+
+    if (persistent &&
+        !bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp))
+    {
+        return;
+    }
+
+    bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
+    if (bitmap != NULL) {
+        bdrv_dirty_bitmap_set_persistance(bitmap, persistent);
+    }
 }
 
 void qmp_block_dirty_bitmap_remove(const char *node, const char *name,

qapi/block-core.json

@@ -1553,10 +1553,16 @@
 # @granularity: the bitmap granularity, default is 64k for
 #               block-dirty-bitmap-add
 #
+# @persistent: the bitmap is persistent, i.e. it will be saved to the
+#              corresponding block device image file on its close. For now only
+#              Qcow2 disks support persistent bitmaps. Default is false for
+#              block-dirty-bitmap-add. (Since: 2.10)
+#
 # Since: 2.4
 ##
 { 'struct': 'BlockDirtyBitmapAdd',
-  'data': { 'node': 'str', 'name': 'str', '*granularity': 'uint32' } }
+  'data': { 'node': 'str', 'name': 'str', '*granularity': 'uint32',
+            '*persistent': 'bool' } }
 
 ##
 # @block-dirty-bitmap-add: