else
                btrfs_set_header_owner(cow, new_root_objectid);
 
-       write_extent_buffer(cow, root->fs_info->fsid, btrfs_header_fsid(),
-                           BTRFS_FSID_SIZE);
+       write_extent_buffer_fsid(cow, root->fs_info->fsid);
 
        WARN_ON(btrfs_header_generation(buf) > trans->transid);
        if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
        else
                btrfs_set_header_owner(cow, root->root_key.objectid);
 
-       write_extent_buffer(cow, root->fs_info->fsid, btrfs_header_fsid(),
-                           BTRFS_FSID_SIZE);
+       write_extent_buffer_fsid(cow, root->fs_info->fsid);
 
        ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
        if (ret) {
        btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
        btrfs_set_header_owner(c, root->root_key.objectid);
 
-       write_extent_buffer(c, root->fs_info->fsid, btrfs_header_fsid(),
-                           BTRFS_FSID_SIZE);
-
-       write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
-                           btrfs_header_chunk_tree_uuid(c), BTRFS_UUID_SIZE);
+       write_extent_buffer_fsid(c, root->fs_info->fsid);
+       write_extent_buffer_chunk_tree_uuid(c, root->fs_info->chunk_tree_uuid);
 
        btrfs_set_node_key(c, &lower_key, 0);
        btrfs_set_node_blockptr(c, 0, lower->start);
        btrfs_set_header_generation(split, trans->transid);
        btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
        btrfs_set_header_owner(split, root->root_key.objectid);
-       write_extent_buffer(split, root->fs_info->fsid,
-                           btrfs_header_fsid(), BTRFS_FSID_SIZE);
-       write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
-                           btrfs_header_chunk_tree_uuid(split),
-                           BTRFS_UUID_SIZE);
+       write_extent_buffer_fsid(split, root->fs_info->fsid);
+       write_extent_buffer_chunk_tree_uuid(split,
+                       root->fs_info->chunk_tree_uuid);
 
        ret = tree_mod_log_eb_copy(root->fs_info, split, c, 0,
                                   mid, c_nritems - mid);
        btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
        btrfs_set_header_owner(right, root->root_key.objectid);
        btrfs_set_header_level(right, 0);
-       write_extent_buffer(right, fs_info->fsid,
-                           btrfs_header_fsid(), BTRFS_FSID_SIZE);
-
-       write_extent_buffer(right, fs_info->chunk_tree_uuid,
-                           btrfs_header_chunk_tree_uuid(right),
-                           BTRFS_UUID_SIZE);
+       write_extent_buffer_fsid(right, fs_info->fsid);
+       write_extent_buffer_chunk_tree_uuid(right, fs_info->chunk_tree_uuid);
 
        if (split == 0) {
                if (mid <= slot) {
 
        btrfs_set_header_owner(leaf, objectid);
        root->node = leaf;
 
-       write_extent_buffer(leaf, fs_info->fsid, btrfs_header_fsid(),
-                           BTRFS_FSID_SIZE);
-       write_extent_buffer(leaf, fs_info->chunk_tree_uuid,
-                           btrfs_header_chunk_tree_uuid(leaf),
-                           BTRFS_UUID_SIZE);
+       write_extent_buffer_fsid(leaf, fs_info->fsid);
+       write_extent_buffer_chunk_tree_uuid(leaf, fs_info->chunk_tree_uuid);
        btrfs_mark_buffer_dirty(leaf);
 
        root->commit_root = btrfs_root_node(root);
        btrfs_set_header_owner(leaf, BTRFS_TREE_LOG_OBJECTID);
        root->node = leaf;
 
-       write_extent_buffer(root->node, root->fs_info->fsid,
-                           btrfs_header_fsid(), BTRFS_FSID_SIZE);
+       write_extent_buffer_fsid(root->node, root->fs_info->fsid);
        btrfs_mark_buffer_dirty(root->node);
        btrfs_tree_unlock(root->node);
        return root;
 
        btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
        btrfs_set_header_owner(leaf, objectid);
 
-       write_extent_buffer(leaf, root->fs_info->fsid, btrfs_header_fsid(),
-                           BTRFS_FSID_SIZE);
-       write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
-                           btrfs_header_chunk_tree_uuid(leaf),
-                           BTRFS_UUID_SIZE);
+       write_extent_buffer_fsid(leaf, root->fs_info->fsid);
+       write_extent_buffer_chunk_tree_uuid(leaf,
+                       root->fs_info->chunk_tree_uuid);
        btrfs_mark_buffer_dirty(leaf);
 
        inode_item = &root_item->inode;
 
        btrfs_set_dev_extent_chunk_objectid(leaf, extent, chunk_objectid);
        btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);
 
-       write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
-                   btrfs_dev_extent_chunk_tree_uuid(extent), BTRFS_UUID_SIZE);
+       write_extent_buffer_chunk_tree_uuid(leaf,
+                       root->fs_info->chunk_tree_uuid);
 
        btrfs_set_dev_extent_length(leaf, extent, num_bytes);
        btrfs_mark_buffer_dirty(leaf);