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>

1 files changed, 3 insertions, 1 deletions

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) {