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

33 files changed, 286 insertions, 90 deletions

diff --git a/arch/m68k/emu/nfblock.c b/arch/m68k/emu/nfblock.c
index f2a00c5..e9110b9 100644
--- a/arch/m68k/emu/nfblock.c
+++ b/arch/m68k/emu/nfblock.c
@@ -59,7 +59,7 @@ struct nfhd_device {
 	struct gendisk *disk;
 };
 
-static void nfhd_make_request(struct request_queue *queue, struct bio *bio)
+static blk_qc_t nfhd_make_request(struct request_queue *queue, struct bio *bio)
 {
 	struct nfhd_device *dev = queue->queuedata;
 	struct bio_vec bvec;
@@ -77,6 +77,7 @@ static void nfhd_make_request(struct request_queue *queue, struct bio *bio)
 		sec += len;
 	}
 	bio_endio(bio);
+	return BLK_QC_T_NONE;
 }
 
 static int nfhd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index d2b79bc..7a399b4 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -103,7 +103,7 @@ axon_ram_irq_handler(int irq, void *dev)
  * axon_ram_make_request - make_request() method for block device
  * @queue, @bio: see blk_queue_make_request()
  */
-static void
+static blk_qc_t
 axon_ram_make_request(struct request_queue *queue, struct bio *bio)
 {
 	struct axon_ram_bank *bank = bio->bi_bdev->bd_disk->private_data;
@@ -120,7 +120,7 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
 	bio_for_each_segment(vec, bio, iter) {
 		if (unlikely(phys_mem + vec.bv_len > phys_end)) {
 			bio_io_error(bio);
-			return;
+			return BLK_QC_T_NONE;
 		}
 
 		user_mem = page_address(vec.bv_page) + vec.bv_offset;
@@ -133,6 +133,7 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
 		transfered += vec.bv_len;
 	}
 	bio_endio(bio);
+	return BLK_QC_T_NONE;
 }
 
 /**
diff --git a/arch/xtensa/platforms/iss/simdisk.c b/arch/xtensa/platforms/iss/simdisk.c
index fa84ca9..3c3ace2 100644
--- a/arch/xtensa/platforms/iss/simdisk.c
+++ b/arch/xtensa/platforms/iss/simdisk.c
@@ -101,7 +101,7 @@ static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
 	spin_unlock(&dev->lock);
 }
 
-static void simdisk_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t simdisk_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct simdisk *dev = q->queuedata;
 	struct bio_vec bvec;
@@ -119,6 +119,7 @@ static void simdisk_make_request(struct request_queue *q, struct bio *bio)
 	}
 
 	bio_endio(bio);
+	return BLK_QC_T_NONE;
 }
 
 static int simdisk_open(struct block_device *bdev, fmode_t mode)
diff --git a/block/blk-core.c b/block/blk-core.c
index 590cca2..2bbf08c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -809,7 +809,7 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
 }
 EXPORT_SYMBOL(blk_init_queue_node);
 
-static void blk_queue_bio(struct request_queue *q, struct bio *bio);
+static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio);
 
 struct request_queue *
 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
@@ -1678,7 +1678,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
 	blk_rq_bio_prep(req->q, req, bio);
 }
 
-static void blk_queue_bio(struct request_queue *q, struct bio *bio)
+static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
 {
 	const bool sync = !!(bio->bi_rw & REQ_SYNC);
 	struct blk_plug *plug;
@@ -1698,7 +1698,7 @@ static void blk_queue_bio(struct request_queue *q, struct bio *bio)
 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
 		bio->bi_error = -EIO;
 		bio_endio(bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 
 	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
@@ -1713,7 +1713,7 @@ static void blk_queue_bio(struct request_queue *q, struct bio *bio)
 	 */
 	if (!blk_queue_nomerges(q)) {
 		if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
-			return;
+			return BLK_QC_T_NONE;
 	} else
 		request_count = blk_plug_queued_count(q);
 
@@ -1791,6 +1791,8 @@ get_rq:
 out_unlock:
 		spin_unlock_irq(q->queue_lock);
 	}
+
+	return BLK_QC_T_NONE;
 }
 
 /*
@@ -1996,12 +1998,13 @@ end_io:
  * a lower device by calling into generic_make_request recursively, which
  * means the bio should NOT be touched after the call to ->make_request_fn.
  */
-void generic_make_request(struct bio *bio)
+blk_qc_t generic_make_request(struct bio *bio)
 {
 	struct bio_list bio_list_on_stack;
+	blk_qc_t ret = BLK_QC_T_NONE;
 
 	if (!generic_make_request_checks(bio))
-		return;
+		goto out;
 
 	/*
 	 * We only want one ->make_request_fn to be active at a time, else
@@ -2015,7 +2018,7 @@ void generic_make_request(struct bio *bio)
 	 */
 	if (current->bio_list) {
 		bio_list_add(current->bio_list, bio);
-		return;
+		goto out;
 	}
 
 	/* following loop may be a bit non-obvious, and so deserves some
@@ -2040,7 +2043,7 @@ void generic_make_request(struct bio *bio)
 
 		if (likely(blk_queue_enter(q, __GFP_DIRECT_RECLAIM) == 0)) {
 
-			q->make_request_fn(q, bio);
+			ret = q->make_request_fn(q, bio);
 
 			blk_queue_exit(q);
 
@@ -2053,6 +2056,9 @@ void generic_make_request(struct bio *bio)
 		}
 	} while (bio);
 	current->bio_list = NULL; /* deactivate */
+
+out:
+	return ret;
 }
 EXPORT_SYMBOL(generic_make_request);
 
@@ -2066,7 +2072,7 @@ EXPORT_SYMBOL(generic_make_request);
  * interfaces; @bio must be presetup and ready for I/O.
  *
  */
-void submit_bio(int rw, struct bio *bio)
+blk_qc_t submit_bio(int rw, struct bio *bio)
 {
 	bio->bi_rw |= rw;
 
@@ -2100,7 +2106,7 @@ void submit_bio(int rw, struct bio *bio)
 		}
 	}
 
-	generic_make_request(bio);
+	return generic_make_request(bio);
 }
 EXPORT_SYMBOL(submit_bio);
 
@@ -3306,6 +3312,47 @@ void blk_finish_plug(struct blk_plug *plug)
 }
 EXPORT_SYMBOL(blk_finish_plug);
 
+bool blk_poll(struct request_queue *q, blk_qc_t cookie)
+{
+	struct blk_plug *plug;
+	long state;
+
+	if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
+	    !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+		return false;
+
+	plug = current->plug;
+	if (plug)
+		blk_flush_plug_list(plug, false);
+
+	state = current->state;
+	while (!need_resched()) {
+		unsigned int queue_num = blk_qc_t_to_queue_num(cookie);
+		struct blk_mq_hw_ctx *hctx = q->queue_hw_ctx[queue_num];
+		int ret;
+
+		hctx->poll_invoked++;
+
+		ret = q->mq_ops->poll(hctx, blk_qc_t_to_tag(cookie));
+		if (ret > 0) {
+			hctx->poll_success++;
+			set_current_state(TASK_RUNNING);
+			return true;
+		}
+
+		if (signal_pending_state(state, current))
+			set_current_state(TASK_RUNNING);
+
+		if (current->state == TASK_RUNNING)
+			return true;
+		if (ret < 0)
+			break;
+		cpu_relax();
+	}
+
+	return false;
+}
+
 #ifdef CONFIG_PM
 /**
  * blk_pm_runtime_init - Block layer runtime PM initialization routine
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 6f57a11..1cf1878 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -174,6 +174,11 @@ static ssize_t blk_mq_sysfs_rq_list_show(struct blk_mq_ctx *ctx, char *page)
 	return ret;
 }
 
+static ssize_t blk_mq_hw_sysfs_poll_show(struct blk_mq_hw_ctx *hctx, char *page)
+{
+	return sprintf(page, "invoked=%lu, success=%lu\n", hctx->poll_invoked, hctx->poll_success);
+}
+
 static ssize_t blk_mq_hw_sysfs_queued_show(struct blk_mq_hw_ctx *hctx,
 					   char *page)
 {
@@ -295,6 +300,10 @@ static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_cpus = {
 	.attr = {.name = "cpu_list", .mode = S_IRUGO },
 	.show = blk_mq_hw_sysfs_cpus_show,
 };
+static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_poll = {
+	.attr = {.name = "io_poll", .mode = S_IRUGO },
+	.show = blk_mq_hw_sysfs_poll_show,
+};
 
 static struct attribute *default_hw_ctx_attrs[] = {
 	&blk_mq_hw_sysfs_queued.attr,
@@ -304,6 +313,7 @@ static struct attribute *default_hw_ctx_attrs[] = {
 	&blk_mq_hw_sysfs_tags.attr,
 	&blk_mq_hw_sysfs_cpus.attr,
 	&blk_mq_hw_sysfs_active.attr,
+	&blk_mq_hw_sysfs_poll.attr,
 	NULL,
 };
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 694f870..86bd5b2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1198,7 +1198,7 @@ static struct request *blk_mq_map_request(struct request_queue *q,
 	return rq;
 }
 
-static int blk_mq_direct_issue_request(struct request *rq)
+static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie)
 {
 	int ret;
 	struct request_queue *q = rq->q;
@@ -1209,6 +1209,7 @@ static int blk_mq_direct_issue_request(struct request *rq)
 		.list = NULL,
 		.last = 1
 	};
+	blk_qc_t new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
 
 	/*
 	 * For OK queue, we are done. For error, kill it. Any other
@@ -1216,18 +1217,21 @@ static int blk_mq_direct_issue_request(struct request *rq)
 	 * would have done
 	 */
 	ret = q->mq_ops->queue_rq(hctx, &bd);
-	if (ret == BLK_MQ_RQ_QUEUE_OK)
+	if (ret == BLK_MQ_RQ_QUEUE_OK) {
+		*cookie = new_cookie;
 		return 0;
-	else {
-		__blk_mq_requeue_request(rq);
+	}
 
-		if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
-			rq->errors = -EIO;
-			blk_mq_end_request(rq, rq->errors);
-			return 0;
-		}
-		return -1;
+	__blk_mq_requeue_request(rq);
+
+	if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
+		*cookie = BLK_QC_T_NONE;
+		rq->errors = -EIO;
+		blk_mq_end_request(rq, rq->errors);
+		return 0;
 	}
+
+	return -1;
 }
 
 /*
@@ -1235,7 +1239,7 @@ static int blk_mq_direct_issue_request(struct request *rq)
  * but will attempt to bypass the hctx queueing if we can go straight to
  * hardware for SYNC IO.
  */
-static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 {
 	const int is_sync = rw_is_sync(bio->bi_rw);
 	const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
@@ -1244,12 +1248,13 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
 	unsigned int request_count = 0;
 	struct blk_plug *plug;
 	struct request *same_queue_rq = NULL;
+	blk_qc_t cookie;
 
 	blk_queue_bounce(q, &bio);
 
 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
 		bio_io_error(bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 
 	blk_queue_split(q, &bio, q->bio_split);
@@ -1257,13 +1262,15 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
 	if (!is_flush_fua && !blk_queue_nomerges(q)) {
 		if (blk_attempt_plug_merge(q, bio, &request_count,
 					   &same_queue_rq))
-			return;
+			return BLK_QC_T_NONE;
 	} else
 		request_count = blk_plug_queued_count(q);
 
 	rq = blk_mq_map_request(q, bio, &data);
 	if (unlikely(!rq))
-		return;
+		return BLK_QC_T_NONE;
+
+	cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
 
 	if (unlikely(is_flush_fua)) {
 		blk_mq_bio_to_request(rq, bio);
@@ -1302,11 +1309,11 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
 			old_rq = rq;
 		blk_mq_put_ctx(data.ctx);
 		if (!old_rq)
-			return;
-		if (!blk_mq_direct_issue_request(old_rq))
-			return;
+			goto done;
+		if (!blk_mq_direct_issue_request(old_rq, &cookie))
+			goto done;
 		blk_mq_insert_request(old_rq, false, true, true);
-		return;
+		goto done;
 	}
 
 	if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
@@ -1320,13 +1327,15 @@ run_queue:
 		blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
 	}
 	blk_mq_put_ctx(data.ctx);
+done:
+	return cookie;
 }
 
 /*
  * Single hardware queue variant. This will attempt to use any per-process
  * plug for merging and IO deferral.
  */
-static void blk_sq_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
 {
 	const int is_sync = rw_is_sync(bio->bi_rw);
 	const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
@@ -1334,23 +1343,26 @@ static void blk_sq_make_request(struct request_queue *q, struct bio *bio)
 	unsigned int request_count = 0;
 	struct blk_map_ctx data;
 	struct request *rq;
+	blk_qc_t cookie;
 
 	blk_queue_bounce(q, &bio);
 
 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
 		bio_io_error(bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 
 	blk_queue_split(q, &bio, q->bio_split);
 
 	if (!is_flush_fua && !blk_queue_nomerges(q) &&
 	    blk_attempt_plug_merge(q, bio, &request_count, NULL))
-		return;
+		return BLK_QC_T_NONE;
 
 	rq = blk_mq_map_request(q, bio, &data);
 	if (unlikely(!rq))
-		return;
+		return BLK_QC_T_NONE;
+
+	cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
 
 	if (unlikely(is_flush_fua)) {
 		blk_mq_bio_to_request(rq, bio);
@@ -1374,7 +1386,7 @@ static void blk_sq_make_request(struct request_queue *q, struct bio *bio)
 		}
 		list_add_tail(&rq->queuelist, &plug->mq_list);
 		blk_mq_put_ctx(data.ctx);
-		return;
+		return cookie;
 	}
 
 	if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
@@ -1389,6 +1401,7 @@ run_queue:
 	}
 
 	blk_mq_put_ctx(data.ctx);
+	return cookie;
 }
 
 /*
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 31849e3..565b8da 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -317,6 +317,34 @@ queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
 	return ret;
 }
 
+static ssize_t queue_poll_show(struct request_queue *q, char *page)
+{
+	return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page);
+}
+
+static ssize_t queue_poll_store(struct request_queue *q, const char *page,
+				size_t count)
+{
+	unsigned long poll_on;
+	ssize_t ret;
+
+	if (!q->mq_ops || !q->mq_ops->poll)
+		return -EINVAL;
+
+	ret = queue_var_store(&poll_on, page, count);
+	if (ret < 0)
+		return ret;
+
+	spin_lock_irq(q->queue_lock);
+	if (poll_on)
+		queue_flag_set(QUEUE_FLAG_POLL, q);
+	else
+		queue_flag_clear(QUEUE_FLAG_POLL, q);
+	spin_unlock_irq(q->queue_lock);
+
+	return ret;
+}
+
 static struct queue_sysfs_entry queue_requests_entry = {
 	.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_requests_show,
@@ -442,6 +470,12 @@ static struct queue_sysfs_entry queue_random_entry = {
 	.store = queue_store_random,
 };
 
+static struct queue_sysfs_entry queue_poll_entry = {
+	.attr = {.name = "io_poll", .mode = S_IRUGO | S_IWUSR },
+	.show = queue_poll_show,
+	.store = queue_poll_store,
+};
+
 static struct attribute *default_attrs[] = {
 	&queue_requests_entry.attr,
 	&queue_ra_entry.attr,
@@ -466,6 +500,7 @@ static struct attribute *default_attrs[] = {
 	&queue_rq_affinity_entry.attr,
 	&queue_iostats_entry.attr,
 	&queue_random_entry.attr,
+	&queue_poll_entry.attr,
 	NULL,
 };
 
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index b9794ae..c9f9c30 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -323,7 +323,7 @@ out:
 	return err;
 }
 
-static void brd_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct block_device *bdev = bio->bi_bdev;
 	struct brd_device *brd = bdev->bd_disk->private_data;
@@ -358,9 +358,10 @@ static void brd_make_request(struct request_queue *q, struct bio *bio)
 
 out:
 	bio_endio(bio);
-	return;
+	return BLK_QC_T_NONE;
 io_error:
 	bio_io_error(bio);
+	return BLK_QC_T_NONE;
 }
 
 static int brd_rw_page(struct block_device *bdev, sector_t sector,
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 015c6e9..e66d453 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1448,7 +1448,7 @@ extern int proc_details;
 /* drbd_req */
 extern void do_submit(struct work_struct *ws);
 extern void __drbd_make_request(struct drbd_device *, struct bio *, unsigned long);
-extern void drbd_make_request(struct request_queue *q, struct bio *bio);
+extern blk_qc_t drbd_make_request(struct request_queue *q, struct bio *bio);
 extern int drbd_read_remote(struct drbd_device *device, struct drbd_request *req);
 extern int is_valid_ar_handle(struct drbd_request *, sector_t);
 
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 2115926..3ae2c00 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1494,7 +1494,7 @@ void do_submit(struct work_struct *ws)
 	}
 }
 
-void drbd_make_request(struct request_queue *q, struct bio *bio)
+blk_qc_t drbd_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct drbd_device *device = (struct drbd_device *) q->queuedata;
 	unsigned long start_jif;
@@ -1510,6 +1510,7 @@ void drbd_make_request(struct request_queue *q, struct bio *bio)
 
 	inc_ap_bio(device);
 	__drbd_make_request(device, bio, start_jif);
+	return BLK_QC_T_NONE;
 }
 
 void request_timer_fn(unsigned long data)
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 1c9e4fe..6255d1c 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -321,7 +321,7 @@ static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
 	return &nullb->queues[index];
 }
 
-static void null_queue_bio(struct request_queue *q, struct bio *bio)
+static blk_qc_t null_queue_bio(struct request_queue *q, struct bio *bio)
 {
 	struct nullb *nullb = q->queuedata;
 	struct nullb_queue *nq = nullb_to_queue(nullb);
@@ -331,6 +331,7 @@ static void null_queue_bio(struct request_queue *q, struct bio *bio)
 	cmd->bio = bio;
 
 	null_handle_cmd(cmd);
+	return BLK_QC_T_NONE;
 }
 
 static int null_rq_prep_fn(struct request_queue *q, struct request *req)
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 2f477d4..d06c62e 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2441,7 +2441,7 @@ static void pkt_make_request_write(struct request_queue *q, struct bio *bio)
 	}
 }
 
-static void pkt_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t pkt_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct pktcdvd_device *pd;
 	char b[BDEVNAME_SIZE];
@@ -2467,7 +2467,7 @@ static void pkt_make_request(struct request_queue *q, struct bio *bio)
 	 */
 	if (bio_data_dir(bio) == READ) {
 		pkt_make_request_read(pd, bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 
 	if (!test_bit(PACKET_WRITABLE, &pd->flags)) {
@@ -2499,13 +2499,12 @@ static void pkt_make_request(struct request_queue *q, struct bio *bio)
 		pkt_make_request_write(q, split);
 	} while (split != bio);
 
-	return;
+	return BLK_QC_T_NONE;
 end_io:
 	bio_io_error(bio);
+	return BLK_QC_T_NONE;
 }
 
-
-
 static void pkt_init_queue(struct pktcdvd_device *pd)
 {
 	struct request_queue *q = pd->disk->queue;
diff --git a/drivers/block/ps3vram.c b/drivers/block/ps3vram.c
index d89fcac..56847fc 100644
--- a/drivers/block/ps3vram.c
+++ b/drivers/block/ps3vram.c
@@ -598,7 +598,7 @@ out:
 	return next;
 }
 
-static void ps3vram_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t ps3vram_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct ps3_system_bus_device *dev = q->queuedata;
 	struct ps3vram_priv *priv = ps3_system_bus_get_drvdata(dev);
@@ -614,11 +614,13 @@ static void ps3vram_make_request(struct request_queue *q, struct bio *bio)
 	spin_unlock_irq(&priv->lock);
 
 	if (busy)
-		return;
+		return BLK_QC_T_NONE;
 
 	do {
 		bio = ps3vram_do_bio(dev, bio);
 	} while (bio);
+
+	return BLK_QC_T_NONE;
 }
 
 static int ps3vram_probe(struct ps3_system_bus_device *dev)
diff --git a/drivers/block/rsxx/dev.c b/drivers/block/rsxx/dev.c
index 3163e4cdc..e1b8b70 100644
--- a/drivers/block/rsxx/dev.c
+++ b/drivers/block/rsxx/dev.c
@@ -145,7 +145,7 @@ static void bio_dma_done_cb(struct rsxx_cardinfo *card,
 	}
 }
 
-static void rsxx_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t rsxx_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct rsxx_cardinfo *card = q->queuedata;
 	struct rsxx_bio_meta *bio_meta;
@@ -199,7 +199,7 @@ static void rsxx_make_request(struct request_queue *q, struct bio *bio)
 	if (st)
 		goto queue_err;
 
-	return;
+	return BLK_QC_T_NONE;
 
 queue_err:
 	kmem_cache_free(bio_meta_pool, bio_meta);
@@ -207,6 +207,7 @@ req_err:
 	if (st)
 		bio->bi_error = st;
 	bio_endio(bio);
+	return BLK_QC_T_NONE;
 }
 
 /*----------------- Device Setup -------------------*/
diff --git a/drivers/block/umem.c b/drivers/block/umem.c
index 04d6579..7939b9f 100644
--- a/drivers/block/umem.c
+++ b/drivers/block/umem.c
@@ -524,7 +524,7 @@ static int mm_check_plugged(struct cardinfo *card)
 	return !!blk_check_plugged(mm_unplug, card, sizeof(struct blk_plug_cb));
 }
 
-static void mm_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t mm_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct cardinfo *card = q->queuedata;
 	pr_debug("mm_make_request %llu %u\n",
@@ -541,7 +541,7 @@ static void mm_make_request(struct request_queue *q, struct bio *bio)
 		activate(card);
 	spin_unlock_irq(&card->lock);
 
-	return;
+	return BLK_QC_T_NONE;
 }
 
 static irqreturn_t mm_interrupt(int irq, void *__card)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 81a557c..47915d7 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -894,7 +894,7 @@ out:
 /*
  * Handler function for all zram I/O requests.
  */
-static void zram_make_request(struct request_queue *queue, struct bio *bio)
+static blk_qc_t zram_make_request(struct request_queue *queue, struct bio *bio)
 {
 	struct zram *zram = queue->queuedata;
 
@@ -911,11 +911,12 @@ static void zram_make_request(struct request_queue *queue, struct bio *bio)
 
 	__zram_make_request(zram, bio);
 	zram_meta_put(zram);
-	return;
+	return BLK_QC_T_NONE;
 put_zram:
 	zram_meta_put(zram);
 error:
 	bio_io_error(bio);
+	return BLK_QC_T_NONE;
 }
 
 static void zram_slot_free_notify(struct block_device *bdev,
diff --git a/drivers/lightnvm/rrpc.c b/drivers/lightnvm/rrpc.c
index 64a888a..7ba64c8 100644
--- a/drivers/lightnvm/rrpc.c
+++ b/drivers/lightnvm/rrpc.c
@@ -803,7 +803,7 @@ static int rrpc_submit_io(struct rrpc *rrpc, struct bio *bio,
 	return NVM_IO_OK;
 }
 
-static void rrpc_make_rq(struct request_queue *q, struct bio *bio)
+static blk_qc_t rrpc_make_rq(struct request_queue *q, struct bio *bio)
 {
 	struct rrpc *rrpc = q->queuedata;
 	struct nvm_rq *rqd;
@@ -811,21 +811,21 @@ static void rrpc_make_rq(struct request_queue *q, struct bio *bio)
 
 	if (bio->bi_rw & REQ_DISCARD) {
 		rrpc_discard(rrpc, bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 
 	rqd = mempool_alloc(rrpc->rq_pool, GFP_KERNEL);
 	if (!rqd) {
 		pr_err_ratelimited("rrpc: not able to queue bio.");
 		bio_io_error(bio);
-		return;
+		return BLK_QC_T_NONE;
 	}
 	memset(rqd, 0, sizeof(struct nvm_rq));
 
 	err = rrpc_submit_io(rrpc, bio, rqd, NVM_IOTYPE_NONE);
 	switch (err) {
 	case NVM_IO_OK:
-		return;
+		return BLK_QC_T_NONE;
 	case NVM_IO_ERR:
 		bio_io_error(bio);
 		break;
@@ -841,6 +841,7 @@ static void rrpc_make_rq(struct request_queue *q, struct bio *bio)
 	}
 
 	mempool_free(rqd, rrpc->rq_pool);
+	return BLK_QC_T_NONE;
 }
 
 static void rrpc_requeue(struct work_struct *work)
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 8e9877b..25fa844 100644
--- a/drivers/md/bcache/request.c
+++ b/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,
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 32440ad..6e15f35 100644
--- a/drivers/md/dm.c
+++ b/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)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 3f9a514..807095f 100644
--- a/drivers/md/md.c
+++ b/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
diff --git a/drivers/nvdimm/blk.c b/drivers/nvdimm/blk.c
index 0df77cb..91a336e 100644
--- a/drivers/nvdimm/blk.c
+++ b/drivers/nvdimm/blk.c
@@ -161,7 +161,7 @@ static int nd_blk_do_bvec(struct nd_blk_device *blk_dev,
 	return err;
 }
 
-static void nd_blk_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t nd_blk_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct block_device *bdev = bio->bi_bdev;
 	struct gendisk *disk = bdev->bd_disk;
@@ -208,6 +208,7 @@ static void nd_blk_make_request(struct request_queue *q, struct bio *bio)
 
  out:
 	bio_endio(bio);
+	return BLK_QC_T_NONE;
 }
 
 static int nd_blk_rw_bytes(struct nd_namespace_common *ndns,
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index eae93ab..efb2c1c 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1150,7 +1150,7 @@ static int btt_do_bvec(struct btt *btt, struct bio_integrity_payload *bip,
 	return ret;
 }
 
-static void btt_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t btt_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct bio_integrity_payload *bip = bio_integrity(bio);
 	struct btt *btt = q->queuedata;
@@ -1198,6 +1198,7 @@ static void btt_make_request(struct request_queue *q, struct bio *bio)
 
 out:
 	bio_endio(bio);
+	return BLK_QC_T_NONE;
 }
 
 static int btt_rw_page(struct block_device *bdev, sector_t sector,
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 349f03e..012e064 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -64,7 +64,7 @@ static void pmem_do_bvec(struct pmem_device *pmem, struct page *page,
 	kunmap_atomic(mem);
 }
 
-static void pmem_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 {
 	bool do_acct;
 	unsigned long start;
@@ -84,6 +84,7 @@ static void pmem_make_request(struct request_queue *q, struct bio *bio)
 		wmb_pmem();
 
 	bio_endio(bio);
+	return BLK_QC_T_NONE;
 }
 
 static int pmem_rw_page(struct block_device *bdev, sector_t sector,
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 97b6640..3dfc288 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -90,7 +90,7 @@ static struct class *nvme_class;
 
 static int __nvme_reset(struct nvme_dev *dev);
 static int nvme_reset(struct nvme_dev *dev);
-static int nvme_process_cq(struct nvme_queue *nvmeq);
+static void nvme_process_cq(struct nvme_queue *nvmeq);
 static void nvme_dead_ctrl(struct nvme_dev *dev);
 
 struct async_cmd_info {
@@ -935,7 +935,7 @@ static int nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
 	return BLK_MQ_RQ_QUEUE_BUSY;
 }
 
-static int nvme_process_cq(struct nvme_queue *nvmeq)
+static void __nvme_process_cq(struct nvme_queue *nvmeq, unsigned int *tag)
 {
 	u16 head, phase;
 
@@ -953,6 +953,8 @@ static int nvme_process_cq(struct nvme_queue *nvmeq)
 			head = 0;
 			phase = !phase;
 		}
+		if (tag && *tag == cqe.command_id)
+			*tag = -1;
 		ctx = nvme_finish_cmd(nvmeq, cqe.command_id, &fn);
 		fn(nvmeq, ctx, &cqe);
 	}
@@ -964,14 +966,18 @@ static int nvme_process_cq(struct nvme_queue *nvmeq)
 	 * a big problem.
 	 */
 	if (head == nvmeq->cq_head && phase == nvmeq->cq_phase)
-		return 0;
+		return;
 
 	writel(head, nvmeq->q_db + nvmeq->dev->db_stride);
 	nvmeq->cq_head = head;
 	nvmeq->cq_phase = phase;
 
 	nvmeq->cqe_seen = 1;
-	return 1;
+}
+
+static void nvme_process_cq(struct nvme_queue *nvmeq)
+{
+	__nvme_process_cq(nvmeq, NULL);
 }
 
 static irqreturn_t nvme_irq(int irq, void *data)
@@ -995,6 +1001,23 @@ static irqreturn_t nvme_irq_check(int irq, void *data)
 	return IRQ_WAKE_THREAD;
 }
 
+static int nvme_poll(struct blk_mq_hw_ctx *hctx, unsigned int tag)
+{
+	struct nvme_queue *nvmeq = hctx->driver_data;
+
+	if ((le16_to_cpu(nvmeq->cqes[nvmeq->cq_head].status) & 1) ==
+	    nvmeq->cq_phase) {
+		spin_lock_irq(&nvmeq->q_lock);
+		__nvme_process_cq(nvmeq, &tag);
+		spin_unlock_irq(&nvmeq->q_lock);
+
+		if (tag == -1)
+			return 1;
+	}
+
+	return 0;
+}
+
 /*
  * Returns 0 on success.  If the result is negative, it's a Linux error code;
  * if the result is positive, it's an NVM Express status code
@@ -1656,6 +1679,7 @@ static struct blk_mq_ops nvme_mq_ops = {
 	.init_hctx	= nvme_init_hctx,
 	.init_request	= nvme_init_request,
 	.timeout	= nvme_timeout,
+	.poll		= nvme_poll,
 };
 
 static void nvme_dev_remove_admin(struct nvme_dev *dev)
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 5ed44fe..94a8f4a 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -27,7 +27,8 @@
 
 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
-static void dcssblk_make_request(struct request_queue *q, struct bio *bio);
+static blk_qc_t dcssblk_make_request(struct request_queue *q,
+						struct bio *bio);
 static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
 			 void __pmem **kaddr, unsigned long *pfn);
 
@@ -815,7 +816,7 @@ dcssblk_release(struct gendisk *disk, fmode_t mode)
 	up_write(&dcssblk_devices_sem);
 }
 
-static void
+static blk_qc_t
 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 {
 	struct dcssblk_dev_info *dev_info;
@@ -874,9 +875,10 @@ dcssblk_make_request(struct request_queue *q, struct bio *bio)
 		bytes_done += bvec.bv_len;
 	}
 	bio_endio(bio);
-	return;
+	return BLK_QC_T_NONE;
 fail:
 	bio_io_error(bio);
+	return BLK_QC_T_NONE;
 }
 
 static long
diff --git a/drivers/s390/block/xpram.c b/drivers/s390/block/xpram.c
index 02871f1..288f59a 100644
--- a/drivers/s390/block/xpram.c
+++ b/drivers/s390/block/xpram.c
@@ -181,7 +181,7 @@ static unsigned long xpram_highest_page_index(void)
 /*
  * Block device make request function.
  */
-static void xpram_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t xpram_make_request(struct request_queue *q, struct bio *bio)
 {
 	xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
 	struct bio_vec bvec;
@@ -223,9 +223,10 @@ static void xpram_make_request(struct request_queue *q, struct bio *bio)
 		}
 	}
 	bio_endio(bio);
-	return;
+	return BLK_QC_T_NONE;
 fail:
 	bio_io_error(bio);
+	return BLK_QC_T_NONE;
 }
 
 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
diff --git a/drivers/staging/lustre/lustre/llite/lloop.c b/drivers/staging/lustre/lustre/llite/lloop.c
index e6974c3..fed50d5 100644
--- a/drivers/staging/lustre/lustre/llite/lloop.c
+++ b/drivers/staging/lustre/lustre/llite/lloop.c
@@ -333,7 +333,7 @@ static unsigned int loop_get_bio(struct lloop_device *lo, struct bio **req)
 	return count;
 }
 
-static void loop_make_request(struct request_queue *q, struct bio *old_bio)
+static blk_qc_t loop_make_request(struct request_queue *q, struct bio *old_bio)
 {
 	struct lloop_device *lo = q->queuedata;
 	int rw = bio_rw(old_bio);
@@ -364,9 +364,10 @@ static void loop_make_request(struct request_queue *q, struct bio *old_bio)
 		goto err;
 	}
 	loop_add_bio(lo, old_bio);
-	return;
+	return BLK_QC_T_NONE;
 err:
 	bio_io_error(old_bio);
+	return BLK_QC_T_NONE;
 }
 
 static inline void loop_handle_bio(struct lloop_device *lo, struct bio *bio)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 18e7554..cb5337d 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -109,6 +109,8 @@ struct dio_submit {
 struct dio {
 	int flags;			/* doesn't change */
 	int rw;
+	blk_qc_t bio_cookie;
+	struct block_device *bio_bdev;
 	struct inode *inode;
 	loff_t i_size;			/* i_size when submitted */
 	dio_iodone_t *end_io;		/* IO completion function */
@@ -397,11 +399,14 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
 	if (dio->is_async && dio->rw == READ && dio->should_dirty)
 		bio_set_pages_dirty(bio);
 
-	if (sdio->submit_io)
+	dio->bio_bdev = bio->bi_bdev;
+
+	if (sdio->submit_io) {
 		sdio->submit_io(dio->rw, bio, dio->inode,
 			       sdio->logical_offset_in_bio);
-	else
-		submit_bio(dio->rw, bio);
+		dio->bio_cookie = BLK_QC_T_NONE;
+	} else
+		dio->bio_cookie = submit_bio(dio->rw, bio);
 
 	sdio->bio = NULL;
 	sdio->boundary = 0;
@@ -440,7 +445,8 @@ static struct bio *dio_await_one(struct dio *dio)
 		__set_current_state(TASK_UNINTERRUPTIBLE);
 		dio->waiter = current;
 		spin_unlock_irqrestore(&dio->bio_lock, flags);
-		io_schedule();
+		if (!blk_poll(bdev_get_queue(dio->bio_bdev), dio->bio_cookie))
+			io_schedule();
 		/* wake up sets us TASK_RUNNING */
 		spin_lock_irqsave(&dio->bio_lock, flags);
 		dio->waiter = NULL;
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 83cc9d4..daf17d7 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;
 
 	/*
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index e813013..641e5a3 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -244,4 +244,28 @@ enum rq_flag_bits {
 #define REQ_MQ_INFLIGHT		(1ULL << __REQ_MQ_INFLIGHT)
 #define REQ_NO_TIMEOUT		(1ULL << __REQ_NO_TIMEOUT)
 
+typedef unsigned int blk_qc_t;
+#define BLK_QC_T_NONE	-1U
+#define BLK_QC_T_SHIFT	16
+
+static inline bool blk_qc_t_valid(blk_qc_t cookie)
+{
+	return cookie != BLK_QC_T_NONE;
+}
+
+static inline blk_qc_t blk_tag_to_qc_t(unsigned int tag, unsigned int queue_num)
+{
+	return tag | (queue_num << BLK_QC_T_SHIFT);
+}
+
+static inline unsigned int blk_qc_t_to_queue_num(blk_qc_t cookie)
+{
+	return cookie >> BLK_QC_T_SHIFT;
+}
+
+static inline unsigned int blk_qc_t_to_tag(blk_qc_t cookie)
+{
+	return cookie & 0xffff;
+}
+
 #endif /* __LINUX_BLK_TYPES_H */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d045ca8..3fe27f8 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -209,7 +209,7 @@ static inline unsigned short req_get_ioprio(struct request *req)
 struct blk_queue_ctx;
 
 typedef void (request_fn_proc) (struct request_queue *q);
-typedef void (make_request_fn) (struct request_queue *q, struct bio *bio);
+typedef blk_qc_t (make_request_fn) (struct request_queue *q, struct bio *bio);
 typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
 
@@ -487,6 +487,7 @@ struct request_queue {
 #define QUEUE_FLAG_DEAD        19	/* queue tear-down finished */
 #define QUEUE_FLAG_INIT_DONE   20	/* queue is initialized */
 #define QUEUE_FLAG_NO_SG_MERGE 21	/* don't attempt to merge SG segments*/
+#define QUEUE_FLAG_POLL	       22	/* IO polling enabled if set */
 
 #define QUEUE_FLAG_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
 				 (1 << QUEUE_FLAG_STACKABLE)	|	\
@@ -761,7 +762,7 @@ static inline void rq_flush_dcache_pages(struct request *rq)
 
 extern int blk_register_queue(struct gendisk *disk);
 extern void blk_unregister_queue(struct gendisk *disk);
-extern void generic_make_request(struct bio *bio);
+extern blk_qc_t generic_make_request(struct bio *bio);
 extern void blk_rq_init(struct request_queue *q, struct request *rq);
 extern void blk_put_request(struct request *);
 extern void __blk_put_request(struct request_queue *, struct request *);
@@ -814,6 +815,8 @@ extern int blk_execute_rq(struct request_queue *, struct gendisk *,
 extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
 				  struct request *, int, rq_end_io_fn *);
 
+bool blk_poll(struct request_queue *q, blk_qc_t cookie);
+
 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 {
 	return bdev->bd_disk->queue;	/* this is never NULL */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9a1cb8c..6230eb2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2613,7 +2613,7 @@ static inline void remove_inode_hash(struct inode *inode)
 extern void inode_sb_list_add(struct inode *inode);
 
 #ifdef CONFIG_BLOCK
-extern void submit_bio(int, struct bio *);
+extern blk_qc_t submit_bio(int, struct bio *);
 extern int bdev_read_only(struct block_device *);
 #endif
 extern int set_blocksize(struct block_device *, int);
diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h
index 5ebd70d..69c9057 100644
--- a/include/linux/lightnvm.h
+++ b/include/linux/lightnvm.h
@@ -426,7 +426,7 @@ static inline struct ppa_addr block_to_ppa(struct nvm_dev *dev,
 	return ppa;
 }
 
-typedef void (nvm_tgt_make_rq_fn)(struct request_queue *, struct bio *);
+typedef blk_qc_t (nvm_tgt_make_rq_fn)(struct request_queue *, struct bio *);
 typedef sector_t (nvm_tgt_capacity_fn)(void *);
 typedef int (nvm_tgt_end_io_fn)(struct nvm_rq *, int);
 typedef void *(nvm_tgt_init_fn)(struct nvm_dev *, struct gendisk *, int, int);