btrfs: split btrfs_alloc_ordered_extent to allocation and insertion helpers

Split two low-level helpers out of btrfs_alloc_ordered_extent to allocate
and insert the logic extent.  The pure alloc helper will be used to
improve btrfs_split_ordered_extent.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ordered-data.c

@@ -146,35 +146,11 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
 	return ret;
 }
 
-/*
- * Add an ordered extent to the per-inode tree.
- *
- * @inode:           Inode that this extent is for.
- * @file_offset:     Logical offset in file where the extent starts.
- * @num_bytes:       Logical length of extent in file.
- * @ram_bytes:       Full length of unencoded data.
- * @disk_bytenr:     Offset of extent on disk.
- * @disk_num_bytes:  Size of extent on disk.
- * @offset:          Offset into unencoded data where file data starts.
- * @flags:           Flags specifying type of extent (1 << BTRFS_ORDERED_*).
- * @compress_type:   Compression algorithm used for data.
- *
- * Most of these parameters correspond to &struct btrfs_file_extent_item. The
- * tree is given a single reference on the ordered extent that was inserted, and
- * the returned pointer is given a second reference.
- *
- * Return: the new ordered extent or error pointer.
- */
-struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
-			struct btrfs_inode *inode, u64 file_offset,
-			u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
-			u64 disk_num_bytes, u64 offset, unsigned long flags,
-			int compress_type)
+static struct btrfs_ordered_extent *alloc_ordered_extent(
+			struct btrfs_inode *inode, u64 file_offset, u64 num_bytes,
+			u64 ram_bytes, u64 disk_bytenr, u64 disk_num_bytes,
+			u64 offset, unsigned long flags, int compress_type)
 {
-	struct btrfs_root *root = inode->root;
-	struct btrfs_fs_info *fs_info = root->fs_info;
-	struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree;
-	struct rb_node *node;
 	struct btrfs_ordered_extent *entry;
 	int ret;
 
@@ -184,7 +160,6 @@ struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
 		ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes);
 		if (ret < 0)
 			return ERR_PTR(ret);
-		ret = 0;
 	} else {
 		/*
 		 * The ordered extent has reserved qgroup space, release now
@@ -209,14 +184,7 @@ struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
 	entry->compress_type = compress_type;
 	entry->truncated_len = (u64)-1;
 	entry->qgroup_rsv = ret;
-
-	ASSERT((flags & ~BTRFS_ORDERED_TYPE_FLAGS) == 0);
 	entry->flags = flags;
-
-	percpu_counter_add_batch(&fs_info->ordered_bytes, num_bytes,
-				 fs_info->delalloc_batch);
-
-	/* one ref for the tree */
 	refcount_set(&entry->refs, 1);
 	init_waitqueue_head(&entry->wait);
 	INIT_LIST_HEAD(&entry->list);
@@ -225,15 +193,40 @@ struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
 	INIT_LIST_HEAD(&entry->work_list);
 	init_completion(&entry->completion);
 
+	/*
+	 * We don't need the count_max_extents here, we can assume that all of
+	 * that work has been done at higher layers, so this is truly the
+	 * smallest the extent is going to get.
+	 */
+	spin_lock(&inode->lock);
+	btrfs_mod_outstanding_extents(inode, 1);
+	spin_unlock(&inode->lock);
+
+	return entry;
+}
+
+static void insert_ordered_extent(struct btrfs_ordered_extent *entry)
+{
+	struct btrfs_inode *inode = BTRFS_I(entry->inode);
+	struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct rb_node *node;
+
 	trace_btrfs_ordered_extent_add(inode, entry);
 
+	percpu_counter_add_batch(&fs_info->ordered_bytes, entry->num_bytes,
+				 fs_info->delalloc_batch);
+
+	/* One ref for the tree. */
+	refcount_inc(&entry->refs);
+
 	spin_lock_irq(&tree->lock);
-	node = tree_insert(&tree->tree, file_offset,
-			   &entry->rb_node);
+	node = tree_insert(&tree->tree, entry->file_offset, &entry->rb_node);
 	if (node)
 		btrfs_panic(fs_info, -EEXIST,
 				"inconsistency in ordered tree at offset %llu",
-				file_offset);
+				entry->file_offset);
 	spin_unlock_irq(&tree->lock);
 
 	spin_lock(&root->ordered_extent_lock);
@@ -247,19 +240,42 @@ struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
 		spin_unlock(&fs_info->ordered_root_lock);
 	}
 	spin_unlock(&root->ordered_extent_lock);
+}
 
-	/*
-	 * We don't need the count_max_extents here, we can assume that all of
-	 * that work has been done at higher layers, so this is truly the
-	 * smallest the extent is going to get.
-	 */
-	spin_lock(&inode->lock);
-	btrfs_mod_outstanding_extents(inode, 1);
-	spin_unlock(&inode->lock);
+/*
+ * Add an ordered extent to the per-inode tree.
+ *
+ * @inode:           Inode that this extent is for.
+ * @file_offset:     Logical offset in file where the extent starts.
+ * @num_bytes:       Logical length of extent in file.
+ * @ram_bytes:       Full length of unencoded data.
+ * @disk_bytenr:     Offset of extent on disk.
+ * @disk_num_bytes:  Size of extent on disk.
+ * @offset:          Offset into unencoded data where file data starts.
+ * @flags:           Flags specifying type of extent (1 << BTRFS_ORDERED_*).
+ * @compress_type:   Compression algorithm used for data.
+ *
+ * Most of these parameters correspond to &struct btrfs_file_extent_item. The
+ * tree is given a single reference on the ordered extent that was inserted, and
+ * the returned pointer is given a second reference.
+ *
+ * Return: the new ordered extent or error pointer.
+ */
+struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
+			struct btrfs_inode *inode, u64 file_offset,
+			u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
+			u64 disk_num_bytes, u64 offset, unsigned long flags,
+			int compress_type)
+{
+	struct btrfs_ordered_extent *entry;
 
-	/* One ref for the returned entry to match semantics of lookup. */
-	refcount_inc(&entry->refs);
+	ASSERT((flags & ~BTRFS_ORDERED_TYPE_FLAGS) == 0);
 
+	entry = alloc_ordered_extent(inode, file_offset, num_bytes, ram_bytes,
+				     disk_bytenr, disk_num_bytes, offset, flags,
+				     compress_type);
+	if (!IS_ERR(entry))
+		insert_ordered_extent(entry);
 	return entry;
 }