NVMe: compat SG_IO ioctl

For 32-bit versions of sg3-utils running on a 64-bit system. This is
mostly a copy from the relevent portions of fs/compat_ioctl.c, with
slight modifications for going through block_device_operations.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@linux.intel.com>
[fixed up CONFIG_COMPAT=n build problems]
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index df3daeb6227f..e44350de8a21 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1568,10 +1568,26 @@ static int nvme_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd,
         }
 }
 
+#ifdef CONFIG_COMPAT
+static int nvme_compat_ioctl(struct block_device *bdev, fmode_t mode,
+                                        unsigned int cmd, unsigned long arg)
+{
+        struct nvme_ns *ns = bdev->bd_disk->private_data;
+
+        switch (cmd) {
+        case SG_IO:
+                return nvme_sg_io32(ns, arg);
+        }
+        return nvme_ioctl(bdev, mode, cmd, arg);
+}
+#else
+#define nvme_compat_ioctl       NULL
+#endif
+
 static const struct block_device_operations nvme_fops = {
         .owner          = THIS_MODULE,
         .ioctl          = nvme_ioctl,
-        .compat_ioctl   = nvme_ioctl,
+        .compat_ioctl   = nvme_compat_ioctl,
 };
 
 static void nvme_resubmit_bios(struct nvme_queue *nvmeq)