[PATCH 02/10] xen/blkfront: drop legacy block layer support

[Bob Liu <bob.liu@oracle.com>]

As Christoph suggested, remove the legacy support similar to most
drivers coverted (virtio, mtip, and nvme).

Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
---
 drivers/block/xen-blkfront.c | 167 +++++++++----------------------------------
 1 file changed, 32 insertions(+), 135 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 13e6178..3589436 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -135,7 +135,6 @@ struct blkfront_info
 	unsigned int max_indirect_segments;
 	int is_ready;
 	struct blk_mq_tag_set tag_set;
-	int feature_multiqueue;
 };
 
 static unsigned int nr_minors;
@@ -606,54 +605,6 @@ static inline bool blkif_request_flush_invalid(struct request *req,
 		 !(info->feature_flush & REQ_FUA)));
 }
 
-/*
- * do_blkif_request
- *  read a block; request is in a request queue
- */
-static void do_blkif_request(struct request_queue *rq)
-{
-	struct blkfront_info *info = NULL;
-	struct request *req;
-	int queued;
-
-	pr_debug("Entered do_blkif_request\n");
-
-	queued = 0;
-
-	while ((req = blk_peek_request(rq)) != NULL) {
-		info = req->rq_disk->private_data;
-
-		if (RING_FULL(&info->ring))
-			goto wait;
-
-		blk_start_request(req);
-
-		if (blkif_request_flush_invalid(req, info)) {
-			__blk_end_request_all(req, -EOPNOTSUPP);
-			continue;
-		}
-
-		pr_debug("do_blk_req %p: cmd %p, sec %lx, "
-			 "(%u/%u) [%s]\n",
-			 req, req->cmd, (unsigned long)blk_rq_pos(req),
-			 blk_rq_cur_sectors(req), blk_rq_sectors(req),
-			 rq_data_dir(req) ? "write" : "read");
-
-		if (blkif_queue_request(req)) {
-			blk_requeue_request(rq, req);
-wait:
-			/* Avoid pointless unplugs. */
-			blk_stop_queue(rq);
-			break;
-		}
-
-		queued++;
-	}
-
-	if (queued != 0)
-		flush_requests(info);
-}
-
 static int blk_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 			const struct blk_mq_queue_data *qd)
 {
@@ -697,27 +648,21 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 	struct request_queue *rq;
 	struct blkfront_info *info = gd->private_data;
 
-	if (info->feature_multiqueue) {
-		memset(&info->tag_set, 0, sizeof(info->tag_set));
-		info->tag_set.ops = &blkfront_mq_ops;
-		info->tag_set.nr_hw_queues = 1;
-		info->tag_set.queue_depth =  BLK_RING_SIZE;
-		info->tag_set.numa_node = NUMA_NO_NODE;
-		info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
-		info->tag_set.cmd_size = 0;
-		info->tag_set.driver_data = info;
-
-		if (blk_mq_alloc_tag_set(&info->tag_set))
-			return -1;
-		rq = blk_mq_init_queue(&info->tag_set);
-		if (IS_ERR(rq)) {
-			blk_mq_free_tag_set(&info->tag_set);
-			return -1;
-		}
-	} else {
-		rq = blk_init_queue(do_blkif_request, &info->io_lock);
-		if (rq == NULL)
-			return -1;
+	memset(&info->tag_set, 0, sizeof(info->tag_set));
+	info->tag_set.ops = &blkfront_mq_ops;
+	info->tag_set.nr_hw_queues = 1;
+	info->tag_set.queue_depth =  BLK_RING_SIZE;
+	info->tag_set.numa_node = NUMA_NO_NODE;
+	info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
+	info->tag_set.cmd_size = 0;
+	info->tag_set.driver_data = info;
+
+	if (blk_mq_alloc_tag_set(&info->tag_set))
+		return -1;
+	rq = blk_mq_init_queue(&info->tag_set);
+	if (IS_ERR(rq)) {
+		blk_mq_free_tag_set(&info->tag_set);
+		return -1;
 	}
 
 	queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
@@ -954,10 +899,7 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
 	spin_lock_irqsave(&info->io_lock, flags);
 
 	/* No more blkif_request(). */
-	if (info->feature_multiqueue)
-		blk_mq_stop_hw_queues(info->rq);
-	else
-		blk_stop_queue(info->rq);
+	blk_mq_stop_hw_queues(info->rq);
 
 	/* No more gnttab callback work. */
 	gnttab_cancel_free_callback(&info->callback);
@@ -980,18 +922,11 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
 	info->gd = NULL;
 }
 
+/* Called with info->io_lock holded */
 static void kick_pending_request_queues(struct blkfront_info *info)
 {
-	if (!RING_FULL(&info->ring)) {
-		if (info->feature_multiqueue) {
-			blk_mq_start_stopped_hw_queues(info->rq, true);
-		} else {
-			/* Re-enable calldowns. */
-			blk_start_queue(info->rq);
-			/* Kick things off immediately. */
-			do_blkif_request(info->rq);
-		}
-	}
+	if (!RING_FULL(&info->ring))
+		blk_mq_start_stopped_hw_queues(info->rq, true);
 }
 
 static void blkif_restart_queue(struct work_struct *work)
@@ -1015,12 +950,8 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 	info->connected = suspend ?
 		BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
 	/* No more blkif_request(). */
-	if (info->rq) {
-		if (info->feature_multiqueue)
-			blk_mq_stop_hw_queues(info->rq);
-		else
-			blk_stop_queue(info->rq);
-	}
+	if (info->rq)
+		blk_mq_stop_hw_queues(info->rq);
 
 	/* Remove all persistent grants */
 	if (!list_empty(&info->grants)) {
@@ -1204,7 +1135,6 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 	RING_IDX i, rp;
 	unsigned long flags;
 	struct blkfront_info *info = (struct blkfront_info *)dev_id;
-	int error;
 
 	spin_lock_irqsave(&info->io_lock, flags);
 
@@ -1245,40 +1175,37 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 			continue;
 		}
 
-		error = req->errors = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
+		req->errors = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
 		switch (bret->operation) {
 		case BLKIF_OP_DISCARD:
 			if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
 				struct request_queue *rq = info->rq;
 				printk(KERN_WARNING "blkfront: %s: %s op failed\n",
 					   info->gd->disk_name, op_name(bret->operation));
-				error = req->errors = -EOPNOTSUPP;
+				req->errors = -EOPNOTSUPP;
 				info->feature_discard = 0;
 				info->feature_secdiscard = 0;
 				queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
 				queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
 			}
-			if (info->feature_multiqueue)
-				blk_mq_complete_request(req);
-			else
-				__blk_end_request_all(req, error);
+			blk_mq_complete_request(req);
 			break;
 		case BLKIF_OP_FLUSH_DISKCACHE:
 		case BLKIF_OP_WRITE_BARRIER:
 			if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
 				printk(KERN_WARNING "blkfront: %s: %s op failed\n",
 				       info->gd->disk_name, op_name(bret->operation));
-				error = req->errors = -EOPNOTSUPP;
+				req->errors = -EOPNOTSUPP;
 			}
 			if (unlikely(bret->status == BLKIF_RSP_ERROR &&
 				     info->shadow[id].req.u.rw.nr_segments == 0)) {
 				printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
 				       info->gd->disk_name, op_name(bret->operation));
-				error = req->errors = -EOPNOTSUPP;
+				req->errors = -EOPNOTSUPP;
 			}
-			if (unlikely(error)) {
-				if (error == -EOPNOTSUPP)
-					error = req->errors = 0;
+			if (unlikely(req->errors)) {
+				if (req->errors == -EOPNOTSUPP)
+					req->errors = 0;
 				info->feature_flush = 0;
 				xlvbd_flush(info);
 			}
@@ -1289,10 +1216,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 				dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
 					"request: %x\n", bret->status);
 
-			if (info->feature_multiqueue)
-				blk_mq_complete_request(req);
-			else
-				__blk_end_request_all(req, error);
+			blk_mq_complete_request(req);
 			break;
 		default:
 			BUG();
@@ -1592,28 +1516,6 @@ static int blkif_recover(struct blkfront_info *info)
 
 	kfree(copy);
 
-	/*
-	 * Empty the queue, this is important because we might have
-	 * requests in the queue with more segments than what we
-	 * can handle now.
-	 */
-	spin_lock_irq(&info->io_lock);
-	while ((req = blk_fetch_request(info->rq)) != NULL) {
-		if (req->cmd_flags &
-		    (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
-			list_add(&req->queuelist, &requests);
-			continue;
-		}
-		merge_bio.head = req->bio;
-		merge_bio.tail = req->biotail;
-		bio_list_merge(&bio_list, &merge_bio);
-		req->bio = NULL;
-		if (req->cmd_flags & (REQ_FLUSH | REQ_FUA))
-			pr_alert("diskcache flush request found!\n");
-		__blk_put_request(info->rq, req);
-	}
-	spin_unlock_irq(&info->io_lock);
-
 	xenbus_switch_state(info->xbdev, XenbusStateConnected);
 
 	spin_lock_irq(&info->io_lock);
@@ -1628,13 +1530,9 @@ static int blkif_recover(struct blkfront_info *info)
 		/* Requeue pending requests (flush or discard) */
 		list_del_init(&req->queuelist);
 		BUG_ON(req->nr_phys_segments > segs);
-		if (info->feature_multiqueue)
-			blk_mq_requeue_request(req);
-		else
-			blk_requeue_request(info->rq, req);
+		blk_mq_requeue_request(req);
 	}
-	if (info->feature_multiqueue)
-		blk_mq_kick_requeue_list(info->rq);
+	blk_mq_kick_requeue_list(info->rq);
 	spin_unlock_irq(&info->io_lock);
 
 	while ((bio = bio_list_pop(&bio_list)) != NULL) {
@@ -1954,7 +1852,6 @@ static void blkfront_connect(struct blkfront_info *info)
 		return;
 	}
 
-	info->feature_multiqueue = 1;
 	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
 				  physical_sector_size);
 	if (err) {
-- 
1.8.3.1