Merge branch 'for-4.4/io-poll' of git://git.kernel.dk/linux-block

Pull block IO poll support from Jens Axboe:
 "Various groups have been doing experimentation around IO polling for
  (really) fast devices.  The code has been reviewed and has been
  sitting on the side for a few releases, but this is now good enough
  for coordinated benchmarking and further experimentation.

  Currently O_DIRECT sync read/write are supported.  A framework is in
  the works that allows scalable stats tracking so we can auto-tune
  this.  And we'll add libaio support as well soon.  Fow now, it's an
  opt-in feature for test purposes"

* 'for-4.4/io-poll' of git://git.kernel.dk/linux-block:
  direct-io: be sure to assign dio->bio_bdev for both paths
  directio: add block polling support
  NVMe: add blk polling support
  block: add block polling support
  blk-mq: return tag/queue combo in the make_request_fn handlers
  block: change ->make_request_fn() and users to return a queue cookie

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 83cc9d4e5455..daf17d70aeca 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -59,6 +59,9 @@ struct blk_mq_hw_ctx {
 
 	struct blk_mq_cpu_notifier	cpu_notifier;
 	struct kobject		kobj;
+
+	unsigned long		poll_invoked;
+	unsigned long		poll_success;
 };
 
 struct blk_mq_tag_set {
@@ -97,6 +100,8 @@ typedef void (exit_request_fn)(void *, struct request *, unsigned int,
 typedef void (busy_iter_fn)(struct blk_mq_hw_ctx *, struct request *, void *,
 		bool);
 typedef void (busy_tag_iter_fn)(struct request *, void *, bool);
+typedef int (poll_fn)(struct blk_mq_hw_ctx *, unsigned int);
+
 
 struct blk_mq_ops {
 	/*
@@ -114,6 +119,11 @@ struct blk_mq_ops {
 	 */
 	timeout_fn		*timeout;
 
+	/*
+	 * Called to poll for completion of a specific tag.
+	 */
+	poll_fn			*poll;
+
 	softirq_done_fn		*complete;
 
 	/*