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

drivers/md/bcache/request.c

@@ -958,7 +958,8 @@ static void cached_dev_nodata(struct closure *cl)
 
 /* Cached devices - read & write stuff */
 
-static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t cached_dev_make_request(struct request_queue *q,
+					struct bio *bio)
 {
 	struct search *s;
 	struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
@@ -997,6 +998,8 @@ static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
 		else
 			generic_make_request(bio);
 	}
+
+	return BLK_QC_T_NONE;
 }
 
 static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
@@ -1070,7 +1073,8 @@ static void flash_dev_nodata(struct closure *cl)
 	continue_at(cl, search_free, NULL);
 }
 
-static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t flash_dev_make_request(struct request_queue *q,
+					     struct bio *bio)
 {
 	struct search *s;
 	struct closure *cl;
@@ -1093,7 +1097,7 @@ static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
 		continue_at_nobarrier(&s->cl,
 				      flash_dev_nodata,
 				      bcache_wq);
-		return;
+		return BLK_QC_T_NONE;
 	} else if (rw) {
 		bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys,
 					&KEY(d->id, bio->bi_iter.bi_sector, 0),
@@ -1109,6 +1113,7 @@ static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
 	}
 
 	continue_at(cl, search_free, NULL);
+	return BLK_QC_T_NONE;
 }
 
 static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode,

drivers/md/dm.c

@@ -1755,7 +1755,7 @@ static void __split_and_process_bio(struct mapped_device *md,
  * The request function that just remaps the bio built up by
  * dm_merge_bvec.
  */
-static void dm_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
 {
 	int rw = bio_data_dir(bio);
 	struct mapped_device *md = q->queuedata;
@@ -1774,12 +1774,12 @@ static void dm_make_request(struct request_queue *q, struct bio *bio)
 			queue_io(md, bio);
 		else
 			bio_io_error(bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 
 	__split_and_process_bio(md, map, bio);
 	dm_put_live_table(md, srcu_idx);
-	return;
+	return BLK_QC_T_NONE;
 }
 
 int dm_request_based(struct mapped_device *md)

drivers/md/md.c

@@ -250,7 +250,7 @@ static DEFINE_SPINLOCK(all_mddevs_lock);
  * call has finished, the bio has been linked into some internal structure
  * and so is visible to ->quiesce(), so we don't need the refcount any more.
  */
-static void md_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
 {
 	const int rw = bio_data_dir(bio);
 	struct mddev *mddev = q->queuedata;
@@ -262,13 +262,13 @@ static void md_make_request(struct request_queue *q, struct bio *bio)
 	if (mddev == NULL || mddev->pers == NULL
 	    || !mddev->ready) {
 		bio_io_error(bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 	if (mddev->ro == 1 && unlikely(rw == WRITE)) {
 		if (bio_sectors(bio) != 0)
 			bio->bi_error = -EROFS;
 		bio_endio(bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 	smp_rmb(); /* Ensure implications of  'active' are visible */
 	rcu_read_lock();
@@ -302,6 +302,8 @@ static void md_make_request(struct request_queue *q, struct bio *bio)
 
 	if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
 		wake_up(&mddev->sb_wait);
+
+	return BLK_QC_T_NONE;
 }
 
 /* mddev_suspend makes sure no new requests are submitted