On Tue, Jan 15, 2019 at 04:16:03PM +0800, Qu Wenruo wrote:
> +int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans,
> + struct btrfs_root *root,
> + struct extent_buffer *subv_eb)
> +{
> + struct btrfs_fs_info *fs_info = root->fs_info;
> + struct btrfs_qgroup_swapped_blocks *blocks = &root->swapped_blocks;
> + struct btrfs_qgroup_swapped_block *block;
> + struct extent_buffer *reloc_eb = NULL;
> + struct rb_node *n;
Please don't use single letter variable here
> + bool found = false;
> + bool swapped = false;
> + int level = btrfs_header_level(subv_eb);
> + int ret = 0;
> + int i;
> +
> + if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
> + return 0;
> + if (!is_fstree(root->root_key.objectid) || !root->reloc_root)
> + return 0;
> +
> + spin_lock(&blocks->lock);
> + if (!blocks->swapped) {
> + spin_unlock(&blocks->lock);
> + goto out;
I think you can return here directly, as this is a shortcut and there's
no state that would need to be cleaned up (ret is still 0).
> + }
> + n = blocks->blocks[level].rb_node;
> +
> + while (n) {
> + block = rb_entry(n, struct btrfs_qgroup_swapped_block, node);
> + if (block->subv_bytenr < subv_eb->start)
> + n = n->rb_left;
> + else if (block->subv_bytenr > subv_eb->start)
> + n = n->rb_right;
> + else {
> + found = true;
> + break;
> + }
> + }
> + if (!found) {
> + spin_unlock(&blocks->lock);
> + goto out;
> + }
> + /* Found one, remove it from @blocks first and update blocks->swapped */
> + rb_erase(&block->node, &blocks->blocks[level]);
> + for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
> + if (RB_EMPTY_ROOT(&blocks->blocks[i])) {
> + swapped = true;
> + break;
> + }
> + }
> + blocks->swapped = swapped;
> + spin_unlock(&blocks->lock);
> +
> + /* Read out reloc subtree root */
> + reloc_eb = read_tree_block(fs_info, block->reloc_bytenr,
> + block->reloc_generation, block->level,
> + &block->first_key);
> + if (IS_ERR(reloc_eb)) {
> + ret = PTR_ERR(subv_eb);
> + reloc_eb = NULL;
> + goto free_out;
> + }
> + if (!extent_buffer_uptodate(reloc_eb)) {
> + ret = -EIO;
> + goto free_out;
> + }
> +
> + ret = qgroup_trace_subtree_swap(trans, reloc_eb, subv_eb,
> + block->last_snapshot, block->trace_leaf);
> +free_out:
> + kfree(block);
> + free_extent_buffer(reloc_eb);
> +out:
> + if (ret < 0) {
> + btrfs_err_rl(fs_info,
> + "failed to account subtree at bytenr %llu: %d",
> + subv_eb->start, ret);
> + fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
> + }
> + return ret;
> +}
