btrfs: Open-code add_delayed_tree_ref

Now that the initialization part and the critical section code have been
split it's a lot easier to open code add_delayed_tree_ref. Do so in the
following manner:

1. The comming init code is put immediately after memory-to-be-initialized
   is allocated, followed by the ref-specific member initialization.

2. The only piece of code that remains in the critical section is
   insert_delayed_ref call.

3. Tracing and memory freeing code is put outside of the critical
   section as well.

The only real change here is an overall shorter critical section when
dealing with delayed tree refs. From functional point of view - the code
is unchanged.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/delayed-ref.c

@@ -695,49 +695,6 @@ static void init_delayed_ref_common(struct btrfs_fs_info *fs_info,
 	INIT_LIST_HEAD(&ref->add_list);
 }
 
-/*
- * helper to insert a delayed tree ref into the rbtree.
- */
-static noinline void
-add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
-		     struct btrfs_trans_handle *trans,
-		     struct btrfs_delayed_ref_head *head_ref,
-		     struct btrfs_delayed_ref_node *ref, u64 bytenr,
-		     u64 num_bytes, u64 parent, u64 ref_root, int level,
-		     int action)
-{
-	struct btrfs_delayed_tree_ref *full_ref;
-	struct btrfs_delayed_ref_root *delayed_refs;
-	u8 ref_type;
-	int ret;
-
-	delayed_refs = &trans->transaction->delayed_refs;
-	full_ref = btrfs_delayed_node_to_tree_ref(ref);
-	if (parent)
-	        ref_type = BTRFS_SHARED_BLOCK_REF_KEY;
-	else
-	        ref_type = BTRFS_TREE_BLOCK_REF_KEY;
-
-	init_delayed_ref_common(fs_info, ref, bytenr, num_bytes, ref_root,
-				action, ref_type);
-	full_ref->root = ref_root;
-	full_ref->parent = parent;
-	full_ref->level = level;
-
-	trace_add_delayed_tree_ref(fs_info, ref, full_ref,
-				   action == BTRFS_ADD_DELAYED_EXTENT ?
-				   BTRFS_ADD_DELAYED_REF : action);
-
-	ret = insert_delayed_ref(trans, delayed_refs, head_ref, ref);
-
-	/*
-	 * XXX: memory should be freed at the same level allocated.
-	 * But bad practice is anywhere... Follow it now. Need cleanup.
-	 */
-	if (ret > 0)
-		kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref);
-}
-
 /*
  * helper to insert a delayed data ref into the rbtree.
  */
@@ -794,12 +751,24 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 	struct btrfs_qgroup_extent_record *record = NULL;
 	int qrecord_inserted;
 	int is_system = (ref_root == BTRFS_CHUNK_TREE_OBJECTID);
+	int ret;
+	u8 ref_type;
 
 	BUG_ON(extent_op && extent_op->is_data);
 	ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 	if (!ref)
 		return -ENOMEM;
 
+	if (parent)
+		ref_type = BTRFS_SHARED_BLOCK_REF_KEY;
+	else
+		ref_type = BTRFS_TREE_BLOCK_REF_KEY;
+	init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
+				ref_root, action, ref_type);
+	ref->root = ref_root;
+	ref->parent = parent;
+	ref->level = level;
+
 	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 	if (!head_ref)
 		goto free_ref;
@@ -825,10 +794,16 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 					is_system, &qrecord_inserted,
 					old_ref_mod, new_ref_mod);
 
-	add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,
-			     num_bytes, parent, ref_root, level, action);
+
+	ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
 	spin_unlock(&delayed_refs->lock);
 
+	trace_add_delayed_tree_ref(fs_info, &ref->node, ref,
+				   action == BTRFS_ADD_DELAYED_EXTENT ?
+				   BTRFS_ADD_DELAYED_REF : action);
+	if (ret > 0)
+		kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
+
 	if (qrecord_inserted)
 		btrfs_qgroup_trace_extent_post(fs_info, record);