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>

1 files changed, 53 insertions, 15 deletions

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index b28d188d10f8..f44d6cd87ea2 100644
--- 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)