Re: [PATCH v2 2/4] blk-mq-debugfs: Show requeue list

[Ming Lei <ming.lei@redhat.com>]

On Wed, May 31, 2017 at 02:30:48PM -0700, Bart Van Assche wrote:
> When verifying whether or not a blk-mq driver forgot to kick the
> requeue list after having requeued a request it is important to
> be able to verify the contents of the requeue list. Hence export
> that list through debugfs.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Reviewed-by: Hannes Reinecke <hare@suse.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Omar Sandoval <osandov@fb.com>
> Cc: Ming Lei <ming.lei@redhat.com>
> ---
>  block/blk-mq-debugfs.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> index d56ddd7a1285..8b06a12c1461 100644
> --- a/block/blk-mq-debugfs.c
> +++ b/block/blk-mq-debugfs.c
> @@ -308,6 +308,37 @@ int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
>  }
>  EXPORT_SYMBOL_GPL(blk_mq_debugfs_rq_show);
>  
> +static void *queue_requeue_list_start(struct seq_file *m, loff_t *pos)
> +	__acquires(&q->requeue_lock)
> +{
> +	struct request_queue *q = m->private;
> +
> +	spin_lock_irq(&q->requeue_lock);
> +	return seq_list_start(&q->requeue_list, *pos);
> +}
> +
> +static void *queue_requeue_list_next(struct seq_file *m, void *v, loff_t *pos)
> +{
> +	struct request_queue *q = m->private;
> +
> +	return seq_list_next(v, &q->requeue_list, pos);
> +}
> +
> +static void queue_requeue_list_stop(struct seq_file *m, void *v)
> +	__releases(&q->requeue_lock)
> +{
> +	struct request_queue *q = m->private;
> +
> +	spin_unlock_irq(&q->requeue_lock);
> +}
> +
> +static const struct seq_operations queue_requeue_list_seq_ops = {
> +	.start	= queue_requeue_list_start,
> +	.next	= queue_requeue_list_next,
> +	.stop	= queue_requeue_list_stop,
> +	.show	= blk_mq_debugfs_rq_show,
> +};
> +
>  static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
>  	__acquires(&hctx->lock)
>  {
> @@ -665,6 +696,7 @@ const struct file_operations blk_mq_debugfs_fops = {
>  
>  static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
>  	{"poll_stat", 0400, queue_poll_stat_show},
> +	{"requeue_list", 0400, .seq_ops = &queue_requeue_list_seq_ops},
>  	{"state", 0600, queue_state_show, queue_state_write},
>  	{},
>  };
> -- 
> 2.12.2
> 

Reviewed-by: Ming Lei <ming.lei@redhat.com>

thanks,
Ming