qcow2: add .bdrv_remove_persistent_dirty_bitmap

Realize .bdrv_remove_persistent_dirty_bitmap interface.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20170628120530.31251-29-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

block/qcow2-bitmap.c

@@ -1237,6 +1237,47 @@ static Qcow2Bitmap *find_bitmap_by_name(Qcow2BitmapList *bm_list,
     return NULL;
 }
 
+void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
+                                          const char *name,
+                                          Error **errp)
+{
+    int ret;
+    BDRVQcow2State *s = bs->opaque;
+    Qcow2Bitmap *bm;
+    Qcow2BitmapList *bm_list;
+
+    if (s->nb_bitmaps == 0) {
+        /* Absence of the bitmap is not an error: see explanation above
+         * bdrv_remove_persistent_dirty_bitmap() definition. */
+        return;
+    }
+
+    bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
+                               s->bitmap_directory_size, errp);
+    if (bm_list == NULL) {
+        return;
+    }
+
+    bm = find_bitmap_by_name(bm_list, name);
+    if (bm == NULL) {
+        goto fail;
+    }
+
+    QSIMPLEQ_REMOVE(bm_list, bm, Qcow2Bitmap, entry);
+
+    ret = update_ext_header_and_dir(bs, bm_list);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Failed to update bitmap extension");
+        goto fail;
+    }
+
+    free_bitmap_clusters(bs, &bm->table);
+
+fail:
+    bitmap_free(bm);
+    bitmap_list_free(bm_list);
+}
+
 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
 {
     BdrvDirtyBitmap *bitmap;

block/qcow2.c

@@ -3990,6 +3990,7 @@ BlockDriver bdrv_qcow2 = {
 
     .bdrv_reopen_bitmaps_rw = qcow2_reopen_bitmaps_rw,
     .bdrv_can_store_new_dirty_bitmap = qcow2_can_store_new_dirty_bitmap,
+    .bdrv_remove_persistent_dirty_bitmap = qcow2_remove_persistent_dirty_bitmap,
 };
 
 static void bdrv_qcow2_init(void)

block/qcow2.h

@@ -653,5 +653,8 @@ bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
                                       const char *name,
                                       uint32_t granularity,
                                       Error **errp);
+void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
+                                          const char *name,
+                                          Error **errp);
 
 #endif