BUG_ON() Conversion in fs/direct-io.c

this changes if() BUG(); constructs to BUG_ON() which is
cleaner and can better optimized away

Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 910a8ed..b05d1b2 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -929,8 +929,7 @@
 			block_in_page += this_chunk_blocks;
 			dio->blocks_available -= this_chunk_blocks;
 next_block:
-			if (dio->block_in_file > dio->final_block_in_request)
-				BUG();
+			BUG_ON(dio->block_in_file > dio->final_block_in_request);
 			if (dio->block_in_file == dio->final_block_in_request)
 				break;
 		}