btrfs: backref: rename and move drop_backref_node()

With extra comment for drop_backref_node() as it has some similarity
with remove_backref_node(), thus we need extra comment explaining the
difference.

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.h b/fs/btrfs/backref.h
index 0a1f296..a14c79b 100644 (file)
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -311,4 +311,43 @@ static inline void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
        }
 }
 
+static inline void btrfs_backref_unlock_node_buffer(
+               struct btrfs_backref_node *node)
+{
+       if (node->locked) {
+               btrfs_tree_unlock(node->eb);
+               node->locked = 0;
+       }
+}
+
+static inline void btrfs_backref_drop_node_buffer(
+               struct btrfs_backref_node *node)
+{
+       if (node->eb) {
+               btrfs_backref_unlock_node_buffer(node);
+               free_extent_buffer(node->eb);
+               node->eb = NULL;
+       }
+}
+
+/*
+ * Drop the backref node from cache without cleaning up its children
+ * edges.
+ *
+ * This can only be called on node without parent edges.
+ * The children edges are still kept as is.
+ */
+static inline void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
+                                          struct btrfs_backref_node *node)
+{
+       BUG_ON(!list_empty(&node->upper));
+
+       btrfs_backref_drop_node_buffer(node);
+       list_del(&node->list);
+       list_del(&node->lower);
+       if (!RB_EMPTY_NODE(&node->rb_node))
+               rb_erase(&node->rb_node, &tree->rb_root);
+       btrfs_backref_free_node(tree, node);
+}
+
 #endif

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index ec35348..d23b9a5 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -268,37 +268,6 @@ static struct btrfs_backref_node *walk_down_backref(
        *index = 0;
        return NULL;
 }
-
-static void unlock_node_buffer(struct btrfs_backref_node *node)
-{
-       if (node->locked) {
-               btrfs_tree_unlock(node->eb);
-               node->locked = 0;
-       }
-}
-
-static void drop_node_buffer(struct btrfs_backref_node *node)
-{
-       if (node->eb) {
-               unlock_node_buffer(node);
-               free_extent_buffer(node->eb);
-               node->eb = NULL;
-       }
-}
-
-static void drop_backref_node(struct btrfs_backref_cache *tree,
-                             struct btrfs_backref_node *node)
-{
-       BUG_ON(!list_empty(&node->upper));
-
-       drop_node_buffer(node);
-       list_del(&node->list);
-       list_del(&node->lower);
-       if (!RB_EMPTY_NODE(&node->rb_node))
-               rb_erase(&node->rb_node, &tree->rb_root);
-       btrfs_backref_free_node(tree, node);
-}
-
 /*
  * remove a backref node from the backref cache
  */
@@ -322,7 +291,7 @@ static void remove_backref_node(struct btrfs_backref_cache *cache,
 
                if (RB_EMPTY_NODE(&upper->rb_node)) {
                        BUG_ON(!list_empty(&node->upper));
-                       drop_backref_node(cache, node);
+                       btrfs_backref_drop_node(cache, node);
                        node = upper;
                        node->lowest = 1;
                        continue;
@@ -337,7 +306,7 @@ static void remove_backref_node(struct btrfs_backref_cache *cache,
                }
        }
 
-       drop_backref_node(cache, node);
+       btrfs_backref_drop_node(cache, node);
 }
 
 static void update_backref_node(struct btrfs_backref_cache *cache,
@@ -2859,7 +2828,7 @@ static int do_relocation(struct btrfs_trans_handle *trans,
                                if (node->eb->start == bytenr)
                                        goto next;
                        }
-                       drop_node_buffer(upper);
+                       btrfs_backref_drop_node_buffer(upper);
                }
 
                if (!upper->eb) {
@@ -2958,15 +2927,15 @@ static int do_relocation(struct btrfs_trans_handle *trans,
                }
 next:
                if (!upper->pending)
-                       drop_node_buffer(upper);
+                       btrfs_backref_drop_node_buffer(upper);
                else
-                       unlock_node_buffer(upper);
+                       btrfs_backref_unlock_node_buffer(upper);
                if (err)
                        break;
        }
 
        if (!err && node->pending) {
-               drop_node_buffer(node);
+               btrfs_backref_drop_node_buffer(node);
                list_move_tail(&node->list, &rc->backref_cache.changed);
                node->pending = 0;
        }
@@ -4591,7 +4560,7 @@ int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
                BUG_ON(node->bytenr != buf->start &&
                       node->new_bytenr != buf->start);
 
-               drop_node_buffer(node);
+               btrfs_backref_drop_node_buffer(node);
                atomic_inc(&cow->refs);
                node->eb = cow;
                node->new_bytenr = cow->start;