blk-mq-debugfs: Show requeue list

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>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Eduardo Valentin <eduval@amazon.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index d56ddd7a12854e73f2287ef871a3269bc7729bab..8b06a12c14618e01ab613c46d8833173887d76c8 100644 (file)
--- 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},
        {},
 };