btrfs: Open-code add_delayed_data_ref

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

1. The common init function is put immediately after memory-to-be-initialized
   is allocated, followed by the specific data ref 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 moved outside of the critical
   section.

No functional changes, just an overall shorter critical section.

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

@@ -695,44 +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 data ref into the rbtree.
- */
-static noinline void
-add_delayed_data_ref(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, u64 owner,
-		     u64 offset, int action)
-{
-	struct btrfs_delayed_data_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_data_ref(ref);
-	if (parent)
-	        ref_type = BTRFS_SHARED_DATA_REF_KEY;
-	else
-	        ref_type = BTRFS_EXTENT_DATA_REF_KEY;
-
-	init_delayed_ref_common(trans->fs_info, ref, bytenr, num_bytes,
-				ref_root, action, ref_type);
-	full_ref->root = ref_root;
-	full_ref->parent = parent;
-	full_ref->objectid = owner;
-	full_ref->offset = offset;
-
-	trace_add_delayed_data_ref(trans->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);
-	if (ret > 0)
-		kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref);
-}
-
 /*
  * add a delayed tree ref.  This does all of the accounting required
  * to make sure the delayed ref is eventually processed before this
@@ -832,11 +794,25 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 	struct btrfs_delayed_ref_root *delayed_refs;
 	struct btrfs_qgroup_extent_record *record = NULL;
 	int qrecord_inserted;
+	int ret;
+	u8 ref_type;
 
 	ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
 	if (!ref)
 		return -ENOMEM;
 
+	if (parent)
+	        ref_type = BTRFS_SHARED_DATA_REF_KEY;
+	else
+	        ref_type = BTRFS_EXTENT_DATA_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->objectid = owner;
+	ref->offset = offset;
+
+
 	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 	if (!head_ref) {
 		kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
@@ -868,10 +844,16 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 					action, 1, 0, &qrecord_inserted,
 					old_ref_mod, new_ref_mod);
 
-	add_delayed_data_ref(trans, head_ref, &ref->node, bytenr, num_bytes,
-			     parent, ref_root, owner, offset, action);
+	ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
 	spin_unlock(&delayed_refs->lock);
 
+	trace_add_delayed_data_ref(trans->fs_info, &ref->node, ref,
+				   action == BTRFS_ADD_DELAYED_EXTENT ?
+				   BTRFS_ADD_DELAYED_REF : action);
+	if (ret > 0)
+		kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
+
+
 	if (qrecord_inserted)
 		return btrfs_qgroup_trace_extent_post(fs_info, record);
 	return 0;