nvme: factor out a nvme_unmap_data helper

BugLink: http://bugs.launchpad.net/bugs/1531539

This is the counter part to nvme_map_data.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit d4f6c3ab)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/nvme/host/pci.c

@@ -89,10 +89,12 @@ static struct class *nvme_class;
 
 struct nvme_dev;
 struct nvme_queue;
+struct nvme_iod;
 
 static int __nvme_reset(struct nvme_dev *dev);
 static int nvme_reset(struct nvme_dev *dev);
 static void nvme_process_cq(struct nvme_queue *nvmeq);
+static void nvme_unmap_data(struct nvme_dev *dev, struct nvme_iod *iod);
 static void nvme_dead_ctrl(struct nvme_dev *dev);
 
 struct async_cmd_info {
@@ -655,7 +657,6 @@ static void req_completion(struct nvme_queue *nvmeq, void *ctx,
 	struct request *req = iod_get_private(iod);
 	struct nvme_cmd_info *cmd_rq = blk_mq_rq_to_pdu(req);
 	u16 status = le16_to_cpup(&cqe->status) >> 1;
-	bool requeue = false;
 	int error = 0;
 
 	if (unlikely(status)) {
@@ -663,13 +664,14 @@ static void req_completion(struct nvme_queue *nvmeq, void *ctx,
 		    && (jiffies - req->start_time) < req->timeout) {
 			unsigned long flags;
 
-			requeue = true;
+			nvme_unmap_data(nvmeq->dev, iod);
+
 			blk_mq_requeue_request(req);
 			spin_lock_irqsave(req->q->queue_lock, flags);
 			if (!blk_queue_stopped(req->q))
 				blk_mq_kick_requeue_list(req->q);
 			spin_unlock_irqrestore(req->q->queue_lock, flags);
-			goto release_iod;
+			return;
 		}
 
 		if (req->cmd_type == REQ_TYPE_DRV_PRIV) {
@@ -692,21 +694,8 @@ static void req_completion(struct nvme_queue *nvmeq, void *ctx,
 			"completing aborted command with status:%04x\n",
 			error);
 
-release_iod:
-	if (iod->nents) {
-		dma_unmap_sg(nvmeq->dev->dev, iod->sg, iod->nents,
-			rq_data_dir(req) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
-		if (blk_integrity_rq(req)) {
-			if (!rq_data_dir(req))
-				nvme_dif_remap(req, nvme_dif_complete);
-			dma_unmap_sg(nvmeq->dev->dev, iod->meta_sg, 1,
-				rq_data_dir(req) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
-		}
-	}
-	nvme_free_iod(nvmeq->dev, iod);
-
-	if (likely(!requeue))
-		blk_mq_complete_request(req, error);
+	nvme_unmap_data(nvmeq->dev, iod);
+	blk_mq_complete_request(req, error);
 }
 
 static bool nvme_setup_prps(struct nvme_dev *dev, struct nvme_iod *iod,
@@ -837,6 +826,24 @@ static int nvme_map_data(struct nvme_dev *dev, struct nvme_iod *iod,
 	return ret;
 }
 
+static void nvme_unmap_data(struct nvme_dev *dev, struct nvme_iod *iod)
+{
+	struct request *req = iod_get_private(iod);
+	enum dma_data_direction dma_dir = rq_data_dir(req) ?
+			DMA_TO_DEVICE : DMA_FROM_DEVICE;
+
+	if (iod->nents) {
+		dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
+		if (blk_integrity_rq(req)) {
+			if (!rq_data_dir(req))
+				nvme_dif_remap(req, nvme_dif_complete);
+			dma_unmap_sg(dev->dev, iod->meta_sg, 1, dma_dir);
+		}
+	}
+
+	nvme_free_iod(dev, iod);
+}
+
 /*
  * We reuse the small pool to allocate the 16-byte range here as it is not
  * worth having a special pool for these or additional cases to handle freeing