From: Keith Busch <keith.busch@intel.com>
Date: Tue, 6 Nov 2012 18:59:23 +0000 (-0700)
Subject: NVMe: Initialize iod nents to 0
X-Git-Tag: firefly_0821_release~3680^2~856^2~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2b1960341576bf51c01b12fefeb1cc53820923e7;p=firefly-linux-kernel-4.4.55.git

NVMe: Initialize iod nents to 0

For commands that do not map a scatter list, we need to initilaize the iod's
number of sg entries (nents) to 0 and not unmap in this case.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
---

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index 270805cf8d42..993c014d195a 100644
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -337,6 +337,7 @@ nvme_alloc_iod(unsigned nseg, unsigned nbytes, gfp_t gfp)
 		iod->offset = offsetof(struct nvme_iod, sg[nseg]);
 		iod->npages = -1;
 		iod->length = nbytes;
+		iod->nents = 0;
 	}
 
 	return iod;
@@ -377,7 +378,8 @@ static void bio_completion(struct nvme_dev *dev, void *ctx,
 	struct bio *bio = iod->private;
 	u16 status = le16_to_cpup(&cqe->status) >> 1;
 
-	dma_unmap_sg(&dev->pci_dev->dev, iod->sg, iod->nents,
+	if (iod->nents)
+		dma_unmap_sg(&dev->pci_dev->dev, iod->sg, iod->nents,
 			bio_data_dir(bio) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 	nvme_free_iod(dev, iod);
 	if (status) {