+ sg = kcalloc(count, sizeof(*sg), GFP_KERNEL);
+ sg_init_table(sg, count);
+ sg_set_page(&sg[0], pages[0], PAGE_SIZE - offset, offset);
+ length -= (PAGE_SIZE - offset);
+ for (i = 1; i < count; i++) {
+ sg_set_page(&sg[i], pages[i], min_t(int, length, PAGE_SIZE), 0);
+ length -= PAGE_SIZE;
+ }
+
+ err = -ENOMEM;
+ nents = dma_map_sg(&dev->pci_dev->dev, sg, count,
+ write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+ if (!nents)
+ goto put_pages;
+
+ kfree(pages);
+ *sgp = sg;
+ return nents;
+
+ put_pages:
+ for (i = 0; i < count; i++)
+ put_page(pages[i]);
+ kfree(pages);
+ return err;
+}
+
+static void nvme_unmap_user_pages(struct nvme_dev *dev, int write,
+ unsigned long addr, int length,
+ struct scatterlist *sg, int nents)
+{
+ int i, count;
+
+ count = DIV_ROUND_UP(offset_in_page(addr) + length, PAGE_SIZE);
+ dma_unmap_sg(&dev->pci_dev->dev, sg, nents, DMA_FROM_DEVICE);
+
+ for (i = 0; i < count; i++)
+ put_page(sg_page(&sg[i]));
+}
+
+static int nvme_submit_user_admin_command(struct nvme_dev *dev,
+ unsigned long addr, unsigned length,
+ struct nvme_command *cmd)
+{
+ int err, nents;
+ struct scatterlist *sg;
+
+ nents = nvme_map_user_pages(dev, 0, addr, length, &sg);
+ if (nents < 0)
+ return nents;
+ nvme_setup_prps(&cmd->common, sg, length);
+ err = nvme_submit_admin_cmd(dev, cmd, NULL);
+ nvme_unmap_user_pages(dev, 0, addr, length, sg, nents);
+ return err ? -EIO : 0;
+}
+
+static int nvme_identify(struct nvme_ns *ns, unsigned long addr, int cns)
+{
+ struct nvme_command c;