[PATCH] genhd: NULL checking fix

Avoid a possible null-pointer deref.

Found by the Coverity tool
Signed-off-by: Alexander Nyberg <alexn@dsv.su.se>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/block/genhd.c

@@ -660,9 +660,10 @@ int invalidate_partition(struct gendisk *disk, int index)
 {
 	int res = 0;
 	struct block_device *bdev = bdget_disk(disk, index);
-	if (bdev)
+	if (bdev) {
 		res = __invalidate_device(bdev, 1);
 		bdput(bdev);
+	}
 	return res;
 }