btrfs: backref: rename and move remove_backref_node()
Also add comment explaining the cleanup progress, to differ it from
btrfs_backref_drop_node().
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 4837dcf..daac20c 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -2514,3 +2514,48 @@ struct btrfs_backref_edge *btrfs_backref_alloc_edge(
cache->nr_edges++;
return edge;
}
+
+/*
+ * Drop the backref node from cache, also cleaning up all its
+ * upper edges and any uncached nodes in the path.
+ *
+ * This cleanup happens bottom up, thus the node should either
+ * be the lowest node in the cache or a detached node.
+ */
+void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
+ struct btrfs_backref_node *node)
+{
+ struct btrfs_backref_node *upper;
+ struct btrfs_backref_edge *edge;
+
+ if (!node)
+ return;
+
+ BUG_ON(!node->lowest && !node->detached);
+ while (!list_empty(&node->upper)) {
+ edge = list_entry(node->upper.next, struct btrfs_backref_edge,
+ list[LOWER]);
+ upper = edge->node[UPPER];
+ list_del(&edge->list[LOWER]);
+ list_del(&edge->list[UPPER]);
+ btrfs_backref_free_edge(cache, edge);
+
+ if (RB_EMPTY_NODE(&upper->rb_node)) {
+ BUG_ON(!list_empty(&node->upper));
+ btrfs_backref_drop_node(cache, node);
+ node = upper;
+ node->lowest = 1;
+ continue;
+ }
+ /*
+ * Add the node to leaf node list if no other child block
+ * cached.
+ */
+ if (list_empty(&upper->lower)) {
+ list_add_tail(&upper->lower, &cache->leaves);
+ upper->lowest = 1;
+ }
+ }
+
+ btrfs_backref_drop_node(cache, node);
+}