Re: [PATCH 5/6] blk-mq-debugfs: Show busy requests

[Bart Van Assche]

On Mon, 2017-05-01 at 17:17 -0700, Omar Sandoval wrote:
> On Thu, Apr 27, 2017 at 08:54:36AM -0700, Bart Van Assche wrote:
> > +   if (q->queue_hw_ctx[rq->mq_ctx->index_hw] == ctx->hctx &&
> 
> This doesn't look right. ctx->index_hw is the index into hctx->ctxs for
> this ctx. I think you mean blk_mq_map_queue(q, rq->mq_ctx->cpu).

Hello Omar,

Thanks for the feedback. I will integrate this fix when I repost this patch 
series
(after the merge window has closed).

Bart.

Re: [PATCH 5/6] blk-mq-debugfs: Show busy requests

[Omar Sandoval]

On Thu, Apr 27, 2017 at 08:54:36AM -0700, Bart Van Assche wrote:
> Requests that got stuck in a block driver are neither on
> blk_mq_ctx.rq_list nor on any hw dispatch queue. Make these
> visible in debugfs through the "busy" attribute.
> 
> Signed-off-by: Bart Van Assche 
> Cc: Omar Sandoval 
> Cc: Hannes Reinecke 
> ---
>  block/blk-mq-debugfs.c | 38 ++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> index 5092d90e37f6..a5e286e04569 100644
> --- a/block/blk-mq-debugfs.c
> +++ b/block/blk-mq-debugfs.c
> @@ -428,6 +428,43 @@ static const struct file_operations hctx_dispatch_fops = 
> {
>   .release= seq_release,
>  };
>  
> +struct show_busy_ctx {
> + struct seq_file *m;
> + struct blk_mq_hw_ctx*hctx;
> +};
> +
> +static void hctx_show_busy(struct request *rq, void *data, bool reserved)
> +{
> + const struct show_busy_ctx *ctx = data;
> + struct request_queue *q = rq->q;
> +
> + if (q->queue_hw_ctx[rq->mq_ctx->index_hw] == ctx->hctx &&

This doesn't look right. ctx->index_hw is the index into hctx->ctxs for
this ctx. I think you mean blk_mq_map_queue(q, rq->mq_ctx->cpu).

> + test_bit(REQ_ATOM_STARTED, >atomic_flags))
> + blk_mq_debugfs_rq_show(ctx->m, >queuelist);
> +}
> +
> +static int hctx_busy_show(struct seq_file *m, void *v)
> +{
> + struct blk_mq_hw_ctx *hctx = m->private;
> + struct show_busy_ctx ctx = { .m = m, .hctx = hctx };
> +
> + blk_mq_tagset_busy_iter(hctx->queue->tag_set, hctx_show_busy, );
> +
> + return 0;
> +}
> +
> +static int hctx_busy_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, hctx_busy_show, inode->i_private);
> +}
> +
> +static const struct file_operations hctx_busy_fops = {
> + .open   = hctx_busy_open,
> + .read   = seq_read,
> + .llseek = seq_lseek,
> + .release= single_release,
> +};
> +
>  static int hctx_ctx_map_show(struct seq_file *m, void *v)
>  {
>   struct blk_mq_hw_ctx *hctx = m->private;
> @@ -885,6 +922,7 @@ static const struct blk_mq_debugfs_attr 
> blk_mq_debugfs_hctx_attrs[] = {
>   {"state", 0400, _state_fops},
>   {"flags", 0400, _flags_fops},
>   {"dispatch", 0400, _dispatch_fops},
> + {"busy", 0400, _busy_fops},
>   {"ctx_map", 0400, _ctx_map_fops},
>   {"tags", 0400, _tags_fops},
>   {"tags_bitmap", 0400, _tags_bitmap_fops},
> -- 
> 2.12.2
>