compat_ioctl: add scsi_compat_ioctl

In order to move the compat handling for SCSI ioctl commands out of
fs/compat_ioctl.c into the individual drivers, we need a helper function
first to match the native ioctl handler called by sd, sr, st, etc.
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/scsi/scsi_ioctl.c

@@ -189,17 +189,7 @@ static int scsi_ioctl_get_pci(struct scsi_device *sdev, void __user *arg)
 }
 
 
-/**
- * scsi_ioctl - Dispatch ioctl to scsi device
- * @sdev: scsi device receiving ioctl
- * @cmd: which ioctl is it
- * @arg: data associated with ioctl
- *
- * Description: The scsi_ioctl() function differs from most ioctls in that it
- * does not take a major/minor number as the dev field.  Rather, it takes
- * a pointer to a &struct scsi_device.
- */
-int scsi_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
+static int scsi_ioctl_common(struct scsi_device *sdev, int cmd, void __user *arg)
 {
 	char scsi_cmd[MAX_COMMAND_SIZE];
 	struct scsi_sense_hdr sense_hdr;
@@ -266,14 +256,50 @@ int scsi_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
                 return scsi_ioctl_get_pci(sdev, arg);
 	case SG_SCSI_RESET:
 		return scsi_ioctl_reset(sdev, arg);
-	default:
-		if (sdev->host->hostt->ioctl)
-			return sdev->host->hostt->ioctl(sdev, cmd, arg);
 	}
+	return -ENOIOCTLCMD;
+}
+
+/**
+ * scsi_ioctl - Dispatch ioctl to scsi device
+ * @sdev: scsi device receiving ioctl
+ * @cmd: which ioctl is it
+ * @arg: data associated with ioctl
+ *
+ * Description: The scsi_ioctl() function differs from most ioctls in that it
+ * does not take a major/minor number as the dev field.  Rather, it takes
+ * a pointer to a &struct scsi_device.
+ */
+int scsi_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
+{
+	int ret = scsi_ioctl_common(sdev, cmd, arg);
+
+	if (ret != -ENOIOCTLCMD)
+		return ret;
+
+	if (sdev->host->hostt->ioctl)
+		return sdev->host->hostt->ioctl(sdev, cmd, arg);
+
 	return -EINVAL;
 }
 EXPORT_SYMBOL(scsi_ioctl);
 
+#ifdef CONFIG_COMPAT
+int scsi_compat_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
+{
+	int ret = scsi_ioctl_common(sdev, cmd, arg);
+
+	if (ret != -ENOIOCTLCMD)
+		return ret;
+
+	if (sdev->host->hostt->compat_ioctl)
+		return sdev->host->hostt->compat_ioctl(sdev, cmd, arg);
+
+	return ret;
+}
+EXPORT_SYMBOL(scsi_compat_ioctl);
+#endif
+
 /*
  * We can process a reset even when a device isn't fully operable.
  */

include/scsi/scsi_ioctl.h

@@ -44,6 +44,7 @@ typedef struct scsi_fctargaddress {
 int scsi_ioctl_block_when_processing_errors(struct scsi_device *sdev,
 		int cmd, bool ndelay);
 extern int scsi_ioctl(struct scsi_device *, int, void __user *);
+extern int scsi_compat_ioctl(struct scsi_device *sdev, int cmd, void __user *arg);
 
 #endif /* __KERNEL__ */
 #endif /* _SCSI_IOCTL_H */