NVMe: Create nvme_map_user_pages() and nvme_unmap_user_pages()

These are generalisations of the code that was in
nvme_submit_user_admin_command().

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

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index b28d188d10f821dce3f2893eb2afd4d45201c324..f44d6cd87ea266648b52e6604d2c16cb31c5bca4 100644 (file)
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -677,17 +677,22 @@ static int __devinit nvme_configure_admin_queue(struct nvme_dev *dev)
        return result;
 }
 
-static int nvme_submit_user_admin_command(struct nvme_dev *dev, unsigned long addr,
-                                       unsigned length, struct nvme_command *cmd)
+static int nvme_map_user_pages(struct nvme_dev *dev, int write,
+                               unsigned long addr, unsigned length,
+                               struct scatterlist **sgp)
 {
        int i, err, count, nents, offset;
-       struct scatterlist sg[2];
-       struct page *pages[2];
+       struct scatterlist *sg;
+       struct page **pages;
 
        if (addr & 3)
                return -EINVAL;
+       if (!length)
+               return -EINVAL;
+
        offset = offset_in_page(addr);
-       count = ((offset + length) > PAGE_SIZE) ? 2 : 1;
+       count = DIV_ROUND_UP(offset + length, PAGE_SIZE);
+       pages = kcalloc(count, sizeof(*pages), GFP_KERNEL);
 
        err = get_user_pages_fast(addr, count, 1, pages);
        if (err < count) {
@@ -695,27 +700,60 @@ static int nvme_submit_user_admin_command(struct nvme_dev *dev, unsigned long ad
                err = -EFAULT;
                goto put_pages;
        }
+
+       sg = kcalloc(count, sizeof(*sg), GFP_KERNEL);
        sg_init_table(sg, count);
        sg_set_page(&sg[0], pages[0], PAGE_SIZE - offset, offset);
-       if (count > 1)
-               sg_set_page(&sg[1], pages[1], offset, 0);
-       nents = dma_map_sg(&dev->pci_dev->dev, sg, count, DMA_FROM_DEVICE);
+       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;
 
-       nvme_setup_prps(&cmd->common, sg, length);
+       kfree(pages);
+       *sgp = sg;
+       return nents;
 
-       err = nvme_submit_admin_cmd(dev, cmd, NULL);
+ put_pages:
+       for (i = 0; i < count; i++)
+               put_page(pages[i]);
+       kfree(pages);
+       return err;
+}
 
-       if (err)
-               err = -EIO;
+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);
- put_pages:
+
        for (i = 0; i < count; i++)
-               put_page(pages[i]);
+               put_page(sg_page(&sg[i]));
+}
 
-       return err;
+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)