[PATCH 3/5] repair: phase 6 is trivially parallelisable

[Christoph Hellwig]

>  static void
>  add_dotdot_update(
> @@ -64,12 +65,14 @@ add_dotdot_update(
>  		do_error(_("malloc failed add_dotdot_update (%zu bytes)\n"),
>  			sizeof(dotdot_update_t));
>  
> +	pthread_mutex_lock(&dotdot_lock);
>  	dir->next = dotdot_update_list;
>  	dir->irec = irec;
>  	dir->agno = agno;
>  	dir->ino_offset = ino_offset;
>  
>  	dotdot_update_list = dir;
> +	pthread_mutex_unlock(&dotdot_lock);

Would be nice to make this use a list_head if you touch it anyway.
(As a separate patch)

>  static void
>  traverse_ags(
> -	xfs_mount_t 		*mp)
> +	xfs_mount_t		*mp)

Not quite sure what actually changed here, but if you touch it anyway
you might as well use the struct version..

> +	if (!ag_stride) {
> +		work_queue_t	queue;
> +
> +		queue.mp = mp;
> +		pf_args[0] = start_inode_prefetch(0, 1, NULL);
> +		for (i = 0; i < glob_agcount; i++) {
> +			pf_args[(~i) & 1] = start_inode_prefetch(i + 1, 1,
> +					pf_args[i & 1]);
> +			traverse_function(&queue, i, pf_args[i & 1]);
> +		}
> +		return;
>  	}
> +
> +	/*
> +	 * create one worker thread for each segment of the volume
> +	 */
> +	queues = malloc(thread_count * sizeof(work_queue_t));
> +	for (i = 0, agno = 0; i < thread_count; i++) {
> +		create_work_queue(&queues[i], mp, 1);
> +		pf_args[0] = NULL;
> +		for (j = 0; j < ag_stride && agno < glob_agcount; j++, agno++) {
> +			pf_args[0] = start_inode_prefetch(agno, 1, pf_args[0]);
> +			queue_work(&queues[i], traverse_function, agno,
> +				   pf_args[0]);
> +		}
> +	}
> +
> +	/*
> +	 * wait for workers to complete
> +	 */
> +	for (i = 0; i < thread_count; i++)
> +		destroy_work_queue(&queues[i]);
> +	free(queues);


This is the third copy of this code block, might make sense to
consolidate it.

Btw, does anyone remember why we have the libxfs_bcache_overflowed()
special case in phase4, but not anywhere else?