qcow2: store bitmaps on reopening image as read-only

Store bitmaps and mark them read-only on reopening image as read-only.
Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Message-id: 20170628120530.31251-21-vsementsov@virtuozzo.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>

block/qcow2-bitmap.c

@@ -1366,3 +1366,25 @@ fail:
 
     bitmap_list_free(bm_list);
 }
+
+int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp)
+{
+    BdrvDirtyBitmap *bitmap;
+    Error *local_err = NULL;
+
+    qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return -EINVAL;
+    }
+
+    for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap != NULL;
+         bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
+    {
+        if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
+            bdrv_dirty_bitmap_set_readonly(bitmap, true);
+        }
+    }
+
+    return 0;
+}

block/qcow2.c

@@ -1555,6 +1555,11 @@ static int qcow2_reopen_prepare(BDRVReopenState *state,
 
     /* We need to write out any unwritten data if we reopen read-only. */
     if ((state->flags & BDRV_O_RDWR) == 0) {
+        ret = qcow2_reopen_bitmaps_ro(state->bs, errp);
+        if (ret < 0) {
+            goto fail;
+        }
+
         ret = bdrv_flush(state->bs);
         if (ret < 0) {
             goto fail;

block/qcow2.h

@@ -648,5 +648,6 @@ int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
 bool qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp);
 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp);
 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp);
+int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp);
 
 #endif