On Wed, Oct 17, 2018 at 02:56:04PM +0800, Qu Wenruo wrote:
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -7261,6 +7261,115 @@ struct find_free_extent_ctl {
> u64 found_offset;
> };
>
> +
No extra newlines.
> +/*
> + * Helper function for find_free_extent().
> + *
> + * Return -ENOENT to inform caller that we need fallback to unclustered mode.
> + * Return -EAGAIN to inform caller that we need to re-search this block group
> + * Return >0 to inform caller that we find nothing
> + * Return 0 means we have found a location and set ffe_ctl->found_offset.
> + */
> +static int find_free_extent_clustered(struct btrfs_block_group_cache *bg,
> + struct btrfs_free_cluster *last_ptr,
> + struct find_free_extent_ctl *ffe_ctl,
> + struct btrfs_block_group_cache **cluster_bg_ret)
> +{
> + struct btrfs_fs_info *fs_info = bg->fs_info;
> + struct btrfs_block_group_cache *cluster_bg;
> + u64 aligned_cluster;
> + u64 offset;
> + int ret;
> +
> + cluster_bg = btrfs_lock_cluster(bg, last_ptr, ffe_ctl->delalloc);
> + if (!cluster_bg)
> + goto refill_cluster;
> + if (cluster_bg != bg && (cluster_bg->ro ||
> + !block_group_bits(cluster_bg, ffe_ctl->flags)))
> + goto release_cluster;
> +
> + offset = btrfs_alloc_from_cluster(cluster_bg, last_ptr,
> + ffe_ctl->num_bytes, cluster_bg->key.objectid,
> + &ffe_ctl->max_extent_size);
> + if (offset) {
> + /* we have a block, we're done */
> + spin_unlock(&last_ptr->refill_lock);
> + trace_btrfs_reserve_extent_cluster(cluster_bg,
> + ffe_ctl->search_start, ffe_ctl->num_bytes);
> + *cluster_bg_ret = cluster_bg;
> + ffe_ctl->found_offset = offset;
> + return 0;
> + }
> + WARN_ON(last_ptr->block_group != cluster_bg);
> +release_cluster:
> + /* If we are on LOOP_NO_EMPTY_SIZE, we can't set up a new clusters, so
If you move or update comment that does not follow our preferred style,
please fix it.
I'll fix both and maybe more that I find while committing the patches.
> + * lets just skip it and let the allocator find whatever block it can
> + * find. If we reach this point, we will have tried the cluster
> + * allocator plenty of times and not have found anything, so we are
> + * likely way too fragmented for the clustering stuff to find anything.
> + *
> + * However, if the cluster is taken from the current block group,
> + * release the cluster first, so that we stand a better chance of
> + * succeeding in the unclustered allocation.
> + */
