block_device_operations->release() should return void

The value passed is 0 in all but "it can never happen" cases (and those
only in a couple of drivers) *and* it would've been lost on the way
out anyway, even if something tried to pass something meaningful.
Just don't bother.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 41bf720..879990c 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -87,7 +87,7 @@
 static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
 
 static int ubd_open(struct block_device *bdev, fmode_t mode);
-static int ubd_release(struct gendisk *disk, fmode_t mode);
+static void ubd_release(struct gendisk *disk, fmode_t mode);
 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
 		     unsigned int cmd, unsigned long arg);
 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
@@ -1138,7 +1138,7 @@
 	return err;
 }
 
-static int ubd_release(struct gendisk *disk, fmode_t mode)
+static void ubd_release(struct gendisk *disk, fmode_t mode)
 {
 	struct ubd *ubd_dev = disk->private_data;
 
@@ -1146,7 +1146,6 @@
 	if(--ubd_dev->count == 0)
 		ubd_close_dev(ubd_dev);
 	mutex_unlock(&ubd_mutex);
-	return 0;
 }
 
 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,