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-rw-r--r--block.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/block.c b/block.c
index 9f866e8676..b162142609 100644
--- a/block.c
+++ b/block.c
@@ -7034,3 +7034,65 @@ BdrvChild *bdrv_primary_child(BlockDriverState *bs)
return found;
}
+
+static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs,
+ bool stop_on_explicit_filter)
+{
+ BdrvChild *c;
+
+ if (!bs) {
+ return NULL;
+ }
+
+ while (!(stop_on_explicit_filter && !bs->implicit)) {
+ c = bdrv_filter_child(bs);
+ if (!c) {
+ /*
+ * A filter that is embedded in a working block graph must
+ * have a child. Assert this here so this function does
+ * not return a filter node that is not expected by the
+ * caller.
+ */
+ assert(!bs->drv || !bs->drv->is_filter);
+ break;
+ }
+ bs = c->bs;
+ }
+ /*
+ * Note that this treats nodes with bs->drv == NULL as not being
+ * filters (bs->drv == NULL should be replaced by something else
+ * anyway).
+ * The advantage of this behavior is that this function will thus
+ * always return a non-NULL value (given a non-NULL @bs).
+ */
+
+ return bs;
+}
+
+/*
+ * Return the first BDS that has not been added implicitly or that
+ * does not have a filtered child down the chain starting from @bs
+ * (including @bs itself).
+ */
+BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
+{
+ return bdrv_do_skip_filters(bs, true);
+}
+
+/*
+ * Return the first BDS that does not have a filtered child down the
+ * chain starting from @bs (including @bs itself).
+ */
+BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
+{
+ return bdrv_do_skip_filters(bs, false);
+}
+
+/*
+ * For a backing chain, return the first non-filter backing image of
+ * the first non-filter image.
+ */
+BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
+{
+ return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));
+}