Comment 124 for bug 330824

@Derek - that patch is already in Jaunty.

static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac)
...
        list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order],
                                                pa_inode_list) {
                spin_lock(&tmp_pa->pa_lock);
                if (tmp_pa->pa_deleted) {
 ....